Arduino Forum

Community => Website and Forum => Topic started by: Coding Badly on Jul 25, 2011, 09:38 am

Title: Loop Back Test - Sticky?
Post by: Coding Badly on Jul 25, 2011, 09:38 am
One persistent question is "How do I perform a loop-back test?"  There are countless variations on the forum and just as many replies of the form, "I searched for instructions but couldn't find anything".  I think it is time to create easy to understand instructions and turn them into a sticky.

These are the instructions I've been providing...

Quote
1. Disable the processor.  The best option is to remove the processor from the board (with the power removed).  If you cannot or would prefer not to remove the processor, connect a jumper wire between RESET and GND.  This will hold the processor in reset preventing it from running.

2. Jumper TX to RX.

3. Apply power to the board.  Connect the board to the computer.  After a brief pause, Windows should produce a device insertion tone.  Linux may or may not produce a device insertion tone; an entry will be added to the system.

4. Start your favourite terminal application.  Serial Monitor will work fine.

5. Ensure your terminal application is connected to the correct serial port.  The baud rate is irrelevant.

6. Type.  As you type, the characters should be echoed to the screen.  Note: To send data, some terminal applications, like Serial Monitor, require pressing the Enter key or clicking a Send button.



Should "Loop Back Test Instructions" be made into a sticky?

In which forum section?

What should the instructions be?
Title: Re: Loop Back Test - Sticky?
Post by: johnwasser on Jul 25, 2011, 04:16 pm
Note that if your favorite terminal application is Serial Monitor then Step 6 should mention that you have to press Enter to send the text...  It will echo as you type and then appear again when you press enter.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Jul 25, 2011, 05:35 pm

Thanks.  Original post modified.

Anything else?  Answers to the questions?
Title: Re: Loop Back Test - Sticky?
Post by: madworm on Jul 25, 2011, 05:37 pm
Yes please. Make it sticky.

It should be added to the troubleshooting guide as well. The playground also seems to lack a main category devoted to troubleshooting as well. If possible put it on the main page of arduino.cc as well ;-)

And if there's room on the PCB, why not add it to the bottom layer silkscreen as well?
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Jul 25, 2011, 05:44 pm
Between steps 3 and 4 one might consider adding something about listening/checking for proper acknowledgment (the nice gong sound) that the PC detected a new USB device connection. A completely dead FTDI or 8u2 converter would fail at this step. Sometime I have them check the arduino IDE comm menu listing before and after plugging in the arduino to make sure a new comm port is created and displayed in the com port menu before proceeding to the serial monitor, to make sure they are selecting the proper comm number in the IDE or PC terminal application.

Lefty

Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Jul 25, 2011, 06:17 pm

@retrolefty:  Thanks.  What does Linux do to acknowledge a device insertion?  MacOS?
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Jul 25, 2011, 06:33 pm


@retrolefty:  Thanks.  What does Linux do to acknowledge a device insertion?  MacOS?



Don't have a clue, but I'm sure somone around here can tell us.  ;)

Lefty
Title: Re: Loop Back Test - Sticky?
Post by: madworm on Jul 25, 2011, 11:27 pm
Re: linux

Unless it is a mass storage device (camera, sd-card, disk...) usually nothing at all. I can't speak for ubuntu though. Of course it will be logged to system log, but the common user usually doesn't care much about that.

And simple things like serial adapters usually just work out of the box anyway ;-)

An FTDI adapter will create something like this in the syslog:

Code: [Select]

07/25/11 11:25:08 PM linuxbox kernel [25248.700042] usb 2-4: new full speed USB device number 3 using ohci_hcd
07/25/11 11:25:08 PM linuxbox kernel [25248.928051] usb 2-4: New USB device found, idVendor=0403, idProduct=6001
07/25/11 11:25:08 PM linuxbox kernel [25248.928062] usb 2-4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
07/25/11 11:25:08 PM linuxbox kernel [25248.928069] usb 2-4: Product: FT232R USB UART
07/25/11 11:25:08 PM linuxbox kernel [25248.928075] usb 2-4: Manufacturer: FTDI
07/25/11 11:25:08 PM linuxbox kernel [25248.928079] usb 2-4: SerialNumber: A6007nZC
07/25/11 11:25:08 PM linuxbox mtp-probe checking bus 2, device 3: "/sys/devices/pci0000:00/0000:00:02.0/usb2/2-4"
07/25/11 11:25:08 PM linuxbox mtp-probe bus: 2, device: 3 was not an MTP device
07/25/11 11:25:09 PM linuxbox kernel [25250.009207] usbcore: registered new interface driver usbserial
07/25/11 11:25:09 PM linuxbox kernel [25250.009240] USB Serial support registered for generic
07/25/11 11:25:09 PM linuxbox kernel [25250.009298] usbcore: registered new interface driver usbserial_generic
07/25/11 11:25:09 PM linuxbox kernel [25250.009302] usbserial: USB Serial Driver core
07/25/11 11:25:09 PM linuxbox kernel [25250.036587] USB Serial support registered for FTDI USB Serial Device
07/25/11 11:25:09 PM linuxbox kernel [25250.037636] ftdi_sio 2-4:1.0: FTDI USB Serial Device converter detected
07/25/11 11:25:09 PM linuxbox kernel [25250.037741] usb 2-4: Detected FT232RL
07/25/11 11:25:09 PM linuxbox kernel [25250.037747] usb 2-4: Number of endpoints 2
07/25/11 11:25:09 PM linuxbox kernel [25250.037753] usb 2-4: Endpoint 1 MaxPacketSize 64
07/25/11 11:25:09 PM linuxbox kernel [25250.037758] usb 2-4: Endpoint 2 MaxPacketSize 64
07/25/11 11:25:09 PM linuxbox kernel [25250.037763] usb 2-4: Setting MaxPacketSize 64
07/25/11 11:25:09 PM linuxbox kernel [25250.042236] usb 2-4: FTDI USB Serial Device converter now attached to ttyUSB0
07/25/11 11:25:09 PM linuxbox kernel [25250.042286] usbcore: registered new interface driver ftdi_sio
07/25/11 11:25:09 PM linuxbox kernel [25250.042291] ftdi_sio: v1.6.0:USB FTDI Serial Converters Driver


The relevant files are:

'/var/log/messages' on openSUSE
'/var/log/syslog' on ubuntu (probably debian as well)

They can be viewed in a text console/terminal with (start this before inserting the device!):

Code: [Select]
sudo tail -f /var/log/syslog

I'm sure there are GUI tools to show this information as well, but they will vary (drastically) between distributions.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Jul 25, 2011, 11:58 pm
Quote
Between steps 3 and 4 one might consider adding something about listening/checking for proper acknowledgment (the nice gong sound) that the PC detected a new USB device connection.


How about a brief description of what to expect added to step #3?
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Jul 26, 2011, 04:58 am

Quote
Between steps 3 and 4 one might consider adding something about listening/checking for proper acknowledgment (the nice gong sound) that the PC detected a new USB device connection.


How about a brief description of what to expect added to step #3?



Well considering now that not all OS make a new usb connection sound, how about this?

3. With board still not plugged in, open the arduino IDE and check the Tools/Serial Port menu and write down the avalible comm ports, and then close the IDE. Plug in the arduino board, open the IDE and again check the Serial Port menu, there should be a new port number avalible that wasn't listed before, and that is the port number you should select. Failure to see a new port number means either a PC USB driver software problem, or a hardware failure with the FTDI or 8u2 serial converter chip on the board, and no need to proceed any further with this test.

Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Jul 28, 2011, 10:18 am

I can't decide.  When I first started this topic, I envisioned a Loop Back Test as something that would be applied to a board that recently was working correctly but now had a suspect processor.

"Troublesome USB Cable" is also a common occurrence.  Your step #3 would certainly help diagnose that problem.

"Failed to Install Driver" is also common.  Your step #3 would help.

I prefer a short simple test (10 or fewer steps) with short simple steps (each step is a single action with an expected result; typically one or two sentences).  At this moment, I'm leaning towards your step #3 being a separate sticky.

Thoughts?
Title: Re: Loop Back Test - Sticky?
Post by: newbee234 on Aug 02, 2011, 05:48 am
The connect power of the arduino was crossed out in the instructions above.
Does that mean the arduino does not need an external power supply when just the base unit is plugged into the computer?

It is not mentioned anywhere on the web site!
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 02, 2011, 06:29 am
The connect power of the arduino was crossed out in the instructions above.


Correct.  It's impossible to perform a loop-back test unless the board is connected to the computer.  If the board is connected to the computer, it is reasonable to use the computer as the source of power.

Quote
Does that mean the arduino does not need an external power supply when just the base unit is plugged into the computer?


I don't know what a "base unit" is but I'm going to say "yes".

Quote
It is not mentioned anywhere on the web site!


Of course it is.  Search for the Power section...
http://arduino.cc/en/Main/ArduinoBoardUno
Title: Re: Loop Back Test - Sticky?
Post by: newbee234 on Aug 03, 2011, 12:04 pm
Thanks for the answer.

And you are right about it being in the hardware board section.

Newbe -- just finding my way!
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 04, 2011, 03:19 am
Which instructions are better?  Set #1...

Quote
1. Disable the processor.  The best option is to remove the processor from the board (with the power removed).  If you cannot or would prefer not to remove the processor, connect a jumper wire between RESET and GND.  This will hold the processor in reset preventing it from running.

2. Jumper TX to RX.

3. Connect the board to the computer.  After a brief pause, Windows should produce a device insertion tone.  Linux may or may not produce a device insertion tone; an entry will be added to the system.

4. Start your favourite terminal application.  Serial Monitor will work fine.

5. Ensure your terminal application is connected to the correct serial port.  The baud rate is irrelevant.

6. Type.  As you type, the characters should be echoed to the screen.  To send data, some terminal applications, like Serial Monitor, require pressing the Enter key or clicking a Send button.



...or Set #2...

Quote
1. Disconnect power from the board

2. Remove all connections and shields from the board

3. Force the processor to remain in reset by connecting a jumper from RESET to GND

4. Connect a jumper from the TX pin (1 on the Uno) to the RX pin (0 on the Uno)

5. Connect the board to your computer.  After a brief pause Windows will produce a device-insertion tone if sound is enabled.  Linux may or may not produce a device-insertion tone; an entry is added to the system log.

6. Start your favourite terminal application.  Serial Monitor will work fine.

7. Connect the terminal application to the serial port for your board.  The baud rate is irrelevant.

8. Send data by typing.  Everything you type should be echoed back.  To send data, some terminal applications, like Serial Monitor, require pressing the Enter key or clicking a Send button.  If exactly what you send is echoed back then the board passes the test.  This means that the host computer hardware driver, USB cable, and USB to serial converter are all working.

9. Shutdown the terminal application

10. Disconnect the board from the computer

11. Remove the two jumpers

Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Aug 04, 2011, 06:37 am
I think I like set #2 better, mostly because of step 2, which is missing in #1set and could be the cause of many comm failures because miswired external connections to pins 0 & 1.

Lefty
Title: Re: Loop Back Test - Sticky?
Post by: graynomad on Aug 04, 2011, 07:23 am
I hope I'm not splitting hairs but this is for beginners.

Quote
Windows produces a device insertion tone

Not if sound is disabled.

I'd vote for #2.

______
Rob
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 04, 2011, 07:39 am
I think I like set #2 better, mostly because of step 2, which is missing in #1set and could be the cause of many comm failures because miswired external connections to pins 0 & 1.


Excellent point.  Thanks.

Anything else?

I hope I'm not splitting hairs...


That is one of my favourite cartoons!  ]:D  I miss Chuck Jones.  Moving on...

Quote
Windows produces a device insertion tone ... Not if sound is disabled.


If you (or anyone reading this) can think of a way to reword that step let me know.  I'm stuck with variations that are too wordy or difficult to read.

Quote
I'd vote for #2.


Thanks.

Anything else?
Title: Re: Loop Back Test - Sticky?
Post by: graynomad on Aug 04, 2011, 09:24 am
That'll teach me to open my big mouth.

Yes you have to be careful it doesn't get so complex you need a flow chart. How about

Quote
5. Connect the board to your computer.  After a brief pause Windows will produces a device-insertion tone if sound is enabled.  Linux may or may not produce a device-insertion tone; an entry is added to the system log.

_____
Rob
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 04, 2011, 09:39 am
That'll teach me to open my big mouth.


Was it really that painful?

Quote
Yes you have to be careful it doesn't get so complex you need a flow chart.


That's what I was talking about.  My brain was flooded with ... What about no sound output device?  What if the volume is turned down?  What if the device is muted?  Must be sleep deprivation.

Quote
How about


Perfect.  #14 modified with the suggestion.


Anything else?
Title: Re: Loop Back Test - Sticky?
Post by: 3dprinter on Aug 04, 2011, 09:08 pm
#2.

I amwas tempted to test this - I did not think baudrate was irellevant. But rather than voice  an uinformed opinion I tested - and now I know. With hindsight, obvious.

I will do the #2 doing exactly what it says. WIthout enganging too many brain cells (Nice evening here, dusk, beer in hand ... attached picture as proof)

Excellent instructions. I skipped one (by accident) and things did not work - then I did not skip it - and everything worked. It will be interesting to see if the sticky will have many false alarms for the same reason. And no, I cant think of any instruction to add to stop that from happening.

My only comment for possible improvment is that at point 8. If it does echo everything, then the USB/driver/chip is working

(edited this pst to reflect the test was done, rather than just intended)
Title: Re: Loop Back Test - Sticky?
Post by: newbee234 on Aug 05, 2011, 08:24 am

That'll teach me to open my big mouth.

Yes you have to be careful it doesn't get so complex you need a flow chart. How about

Quote
5. Connect the board to your computer.  After a brief pause Windows will produces a device-insertion tone if sound is enabled.  Linux may or may not produce a device-insertion tone; an entry is added to the system log.

_____
Rob


You may also like to add that under linux a new /dev/ttyUSB*  device driver will appear.

The reason is that on (at least fedora or redhat) linux  the 'messages' file is root only readable for security reasons.  where as the existence of a new device driver is something any user can check on.  Basically it is a more convenient thing for a user to look for.

Also note that users will need to be members of the right groups to enabled locking for serial communications. That is something that is noted in the web sites software installation and setup page. The step-by-step instructions however can just point to the right web page for that sort of detail.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 05, 2011, 09:30 am
beer in hand


Looks exotic and foreign.  And tasty.

Quote
Excellent instructions.


Thanks.

Quote
It will be interesting to see if the sticky will have many false alarms for the same reason


With a few years of working technical support under my belt I can say beyond any doubt that there will be false alarms.

Quote
My only comment for possible improvment is that at point 8. If it does echo everything, then the USB/driver/chip is working


Excellent!  Every story needs a conclusion and mine was certainly missing one.

Post #14 updated...
http://arduino.cc/forum/index.php/topic,67509.msg504175.html#msg504175
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 05, 2011, 09:31 am
You may also like to add that under linux a new /dev/ttyUSB*  device driver will appear.


Appear where?

Quote
The step-by-step instructions however can just point to the right web page for that sort of detail.


Link please.

Thanks.
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Aug 05, 2011, 09:42 am
Quote
With a few years of working technical support under my belt I can say beyond any doubt that there will be false alarms.


Ever read the story of a PC telephone support tech trying to get a person's PC working, it was hilarious, seemed it took over 30mins before the person managed to inform the tech that the building also had a total power outage along with the persons PC problem!

Not sure if it was a true story or not, but it was a great read.

Lefty
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 05, 2011, 10:14 am

I have not read it but I can believe it's true!

One thing that used to drive me nuts... I'd go on a support call.  I'd arrive to find the computer connected to the hardware and the supposedly technically competent human grumbling over the keyboard.  They would get up, give me a rundown of what they had tried and leave.  I'd spend about an hour trying to troubleshoot the problem arriving at the conclusion that the cable was the culprit.  When the human returned I would ask, "where did you get this cable?"  The typical reply was, "I found it in a box of old cables.  It had the right connectors on the ends so it has to be the right one."
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 19, 2011, 07:59 am

Last chance.  Any suggestions...

Quote
1. Disconnect power from the board

2. Remove all connections and shields from the board

3. Force the processor to remain in reset by connecting a jumper from RESET to GND

4. Connect a jumper from the TX pin (Digital Pin 1) to the RX pin (Digital Pin 0)

5. Connect the board to your computer.  After a brief pause Windows will produce a device-insertion tone if sound is enabled.  Linux may or may not produce a device-insertion tone; an entry is added to the system log.

6. Start your favourite terminal application.  Serial Monitor will work fine.

7. Connect the terminal application to the serial port for your board.  The baud rate is irrelevant.

8. Send data by typing.  Everything you type should be echoed back.  To send data, some terminal applications, like Serial Monitor, require pressing the Enter key or clicking a Send button.  If exactly what you send is echoed back then the board passes the test.  This means that the host computer hardware driver, USB cable, and USB to serial converter are all working.

9. Shutdown the terminal application

10. Disconnect the board from the computer

11. Remove the two jumpers

Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Aug 19, 2011, 08:57 am
Why the word Uno in step 4? Applies to all arduino boards, might confuse.

Quote
4. Connect a jumper from the TX pin (1 on the Uno) to the RX pin (0 on the Uno)


How about:

Quote
4. Connect a jumper from the TX pin (Pin 1) to the RX pin (Pin 0)

Or:
4. Connect a jumper from the TX pin (Shield pin 1) to the RX pin (Shield pin 0)
Or:
4. Connect a jumper from the TX pin (Arduino Pin 1) to the RX pin (Arduino Pin 0)



Lefty
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 19, 2011, 09:06 am
Quote
Why the word Uno in step 4?


Huh.  Good question.  Digging through my brain reveals... not much.   :D

I guess because I didn't know if pins 0 & 1 are RX & TX on other boards.  Is that consistent with Arduinos?  Is that consistent with compatible boards?
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Aug 19, 2011, 09:21 am

Quote
Why the word Uno in step 4?


Huh.  Good question.  Digging through my brain reveals... not much.   :D

I guess because I didn't know if pins 0 & 1 are RX & TX on other boards.  Is that consistent with Arduinos?  Is that consistent with compatible boards?



Yes, if you are talking about the AVR hardware UART channel, even on the mega it uses (shield) pins 0 and 1 for the Serial channel, where the other three hardware UART channels are in the pins 14 to 19.

You software guys crack me up, often.  ;)

Lefty
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 19, 2011, 09:40 am
Quote
You software guys crack me up, often.


:D  We do what we can to entertain.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 19, 2011, 09:42 am

What do you think of this...

Quote
4. Connect a jumper from the TX pin (Digital Pin 1) to the RX pin (Digital Pin 0)

Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Aug 19, 2011, 10:03 am


What do you think of this...

Quote
4. Connect a jumper from the TX pin (Digital Pin 1) to the RX pin (Digital Pin 0)




I like it.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 19, 2011, 10:06 am

Thanks!

Anyone else?  Anything else?
Title: Re: Loop Back Test - Sticky?
Post by: nickgammon on Sep 11, 2011, 09:20 am
Quote
Connect a jumper from the TX pin (Digital Pin 1) to the RX pin (Digital Pin 0)


Strictly speaking, they aren't pins. If you are going to worry about people not hearing sounds because the volume is down, you might point out that they are sockets. It's the male/female thing. The boards only have a handful of pins, the rest are sockets.




And I can't resist this:


I hope I'm not splitting hairs but this is for beginners.

Quote
Windows produces a device insertion tone

Not if sound is disabled.


Warning: if you are deaf you won't hear it.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Sep 13, 2011, 10:21 am
Strictly speaking, they aren't pins. If you are going to worry about people not hearing sounds because the volume is down, you might point out that they are sockets. It's the male/female thing. The boards only have a handful of pins, the rest are sockets.


You certainly have a valid point.  Unfortunately, the Arduino folks call them "pins" A.  I prefer to use the same term used in the rest of the Arduino documentation to avoid confusion B.

A  Which has been a source of confusion even for advanced users (Did you mean "physical pin" or "Arduino pin"?).

B  Oh, the irony!





Quote
Warning: if you are deaf you won't hear it.


XD

As part of a previous job, I occasionally had to install a complete computer system (PC + custom software).  I arrived at one of the sites and found the two operators.  One of the operators ("Buddy") was bragging to the other ("Juan") about the new tires on his truck.  He claimed to have reached more than 80 miles per hour and successfully navigated an especially sharp corner.  I had a suspicion Buddy would need a bit more training than usual.

I carried in the various computer parts and connected them.  When I left the office to get the software and some notes, the computer was fully assembled so I started it booting.  I returned to the office to find Buddy waving the mouse in front of the monitor with a very confused look on his face.  Juan watched for a moment and then told him, "Buddy, you have to drag it across the table."  I very nearly burst out laughing; I had to actually cover my mouth.  I turned around, walked out the door, sat down in my vehicle, and laughed my gut sore.

Despite his naiveté, Buddy was up to the task.  He quickly learned, not only to use a mouse, but to use the software.

The moral of the story?  While instructions like "Warning: mouse only functions correctly when used on a flat horizontal surface" are sometimes necessary, "Warning: if you are deaf you won't hear it" is probably over the top.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Sep 28, 2011, 07:51 pm

Now a sticky...
http://arduino.cc/forum/index.php/topic,73748.0.html

Please continue posting suggestions here.
Title: Re: Loop Back Test - Sticky?
Post by: madworm on Sep 30, 2011, 09:04 pm
Is it safe to assume that newcomers will know that they should look for how to perform a 'loop back test' when uploading doesn't work?

The title of the sticky post doesn't say anything about failing uploads.
Title: Re: Loop Back Test - Sticky?
Post by: draythomp on Oct 01, 2011, 02:10 am
Actually, after the revisions suggested above, this is really good.  The only thing that struck me was that when I first saw it I asked myself, "What do I want to do a loopback test for?"    Perhaps, something about why one would/should do a loopback test?
Title: Re: Loop Back Test - Sticky?
Post by: radman on Oct 01, 2011, 05:08 pm
I tried the procedure and had no difficulty following it.

The slight change I wanted to suggest was that some of the text in step 8 should be removed and instead there should be a short introduction saying why you would do the test and what it would achieve. I reached this conclusion before reading this thread where one of the comments is;
Quote
The only thing that struck me was that when I first saw it I asked myself, "What do I want to do a loopback test for?"


Suggested text at the start (removing equivalent text in point 8 );
Quote
The loopback test will prove that your host computer hardware driver, USB cable, and USB to serial converter are all working.
Try the loopback test after you first install the system or if you cannot upload sketches.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Oct 05, 2011, 10:50 am
Is it safe to assume that newcomers will know that they should look for how to perform a 'loop back test' when uploading doesn't work?


No. 

Quote
The title of the sticky post doesn't say anything about failing uploads.


What should the title be?

What introduction (cover) should be added?  Perform a loop-back test when...
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Oct 05, 2011, 10:52 am
Actually, after the revisions suggested above, this is really good.


Excellent!

Quote
The only thing that struck me was that when I first saw it I asked myself, "What do I want to do a loopback test for?"    Perhaps, something about why one would/should do a loopback test?


I agree.  One case is: uploading was working, upload is not now working, damaged processor is suspected.  When else would / should a loop-back test be performed?
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Oct 05, 2011, 11:04 am
I tried the procedure and had no difficulty following it.


Excellent!  Thank you.

Quote
The slight change I wanted to suggest was that some of the text in step 8 should be removed


Nope.  Not going to happen.  My Tech-Com II professor stated repeatedly: You tell it to them three times.  You tell them what you are going to tell them in the introduction.  Then you tell them in the body.  Then you tell them what you told them in the conclusion.  After working in technical support for a few years, I strongly agree.  Some people get it the first time they read something.  Some people barely get it the third time they read something.  Troubleshooting instructions need to be written for the latter group; lots of repetition.

Quote
and instead there should be a short introduction saying why you would do the test and what it would achieve


I agree.  It needs an introduction / cover.

Quote
Suggested text at the start (removing equivalent text in point 8 );
Quote
The loopback test will prove that your host computer hardware driver, USB cable, and USB to serial converter are all working.
Try the loopback test after you first install the system or if you cannot upload sketches.


Is it necessary to perform a loop-back test after first installing the system?
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Oct 05, 2011, 05:16 pm
Quote
Is it necessary to perform a loop-back test after first installing the system?


No. The loop-back procedure is a troubleshooting aid/procedure to help one determine if serial communication between the PC and Arduino board is working or not working in a typical arduino installation. It does no harm to run it on a working system, and it would probably be best to learn to run it on a working system before having a problem to prevent false positive (or is it false negative?) testing results.

Lefty  
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Oct 10, 2011, 12:56 am

Is there really just one use-case?  "uploading was working, upload is not now working, damaged processor is suspected"?

How's this for the introduction...

Quote
The loop-back test is a troubleshooting procedure to determine if serial communication between the PC and Arduino board is working in a typical Arduino installation.  The test proves that the host computer, hardware driver, USB cable, and USB to serial converter are all working.


Title: Re: Loop Back Test - Sticky?
Post by: PaulS on Oct 10, 2011, 01:32 am
Quote
How's this for the introduction...

Needs a comma between "host computer" and  "hardware driver". It is testing all 4 items.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Oct 10, 2011, 02:02 am

Thanks!  Done.
Title: Re: Loop Back Test - Sticky?
Post by: tytower on Oct 15, 2011, 10:48 pm

I tried the procedure and had no difficulty following it.


Excellent!  Thank you.

Quote
The slight change I wanted to suggest was that some of the text in step 8 should be removed


Nope.  Not going to happen.  My Tech-Com II professor stated repeatedly: You tell it to them three times.  You tell them what you are going to tell them in the introduction.  Then you tell them in the body.  Then you tell them what you told them in the conclusion.  After working in technical support for a few years, I strongly agree.  Some people get it the first time they read something.  Some people barely get it the third time they read something.  Troubleshooting instructions need to be written for the latter group; lots of repetition.

Quote
and instead there should be a short introduction saying why you would do the test and what it would achieve


I agree.  It needs an introduction / cover.

Quote
Suggested text at the start (removing equivalent text in point 8 );
Quote
The loopback test will prove that your host computer hardware driver, USB cable, and USB to serial converter are all working.
Try the loopback test after you first install the system or if you cannot upload sketches.


Is it necessary to perform a loop-back test after first installing the system?



So treat everybody like dummies because there might be one or two in a dozen !
How did the dummies get into your professors class?
When I went to uni it was stay up or get out
Title: Re: Loop Back Test - Sticky?
Post by: draythomp on Oct 16, 2011, 12:30 am
Not everyone that needs repetition is a dummy.  Some folks read this board in their second or third language.  Some folks use google translate to read it.  Some folks are beginners at everything electronic.  Like it or not, repetition works.  It gives the person a second chance to hear it, it gives the translator a new version to try and screw up differently and it helps to reinforce information.

Besides, being snide doesn't help.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Oct 19, 2011, 09:01 pm

The current state of the introduction...
http://arduino.cc/forum/index.php/topic,67509.msg564416.html#msg564416

We have one use-case.

Should the sticky include references to example / related topics?  Some examples...
http://arduino.cc/forum/index.php/topic,75418.msg568935.html#msg568935
http://arduino.cc/forum/index.php/topic,75651.0.html

Any more comments before I change the sticky?
Title: Re: Loop Back Test - Sticky?
Post by: draythomp on Oct 19, 2011, 11:07 pm
I like the introduction.  Short, and to the point.

I have mixed feelings about the examples, they might confuse more than help.  I'll bow to other's opinions on that.

Good job.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Oct 21, 2011, 08:52 am

Introduction added.

Any more comments about examples / related topics?

Any other use-cases?
Title: Re: Loop Back Test - Sticky?
Post by: patgadget on Nov 23, 2011, 02:47 am
Should try without the jumper as the Terminal program could have a ECHO turn on
Patgadget
Title: Re: Loop Back Test - Sticky?
Post by: madworm on Dec 27, 2011, 04:43 pm
There have been issues with 'clone' boards lately.

They didn't come with either the ATmega8u2 or the FT232R, but with some IC by 'Prolific'. Suffice to say people were still trying to install the FTDI drivers or the .inf file, depending on what their clone pretended to be.

Maybe there could be a note/hint to check the vendor/product IDs if the 'Arduino driver' refuses to install.

Addendum:

Of course we could say "why should we care?", but in the end people with these modified clone boards end up here and we spend our time that would be better spent elsewhere.
Title: Re: Loop Back Test - Sticky?
Post by: chunkymoves on Dec 30, 2011, 07:59 am
"Force the processor to remain in reset by connecting a jumper from RESET to GND"

How do you do this? Have any pictures :-)
Title: Re: Loop Back Test - Sticky?
Post by: CrossRoads on Dec 30, 2011, 09:07 am
Put a piece of wire in the header pin labelled Reset, and the other end in one of three headers pins labelled GND.

(http://arduino.cc/en/uploads/Main/ArduinoUno_R3_Front_450px.jpg)
Title: Re: Loop Back Test - Sticky?
Post by: madworm on Dec 30, 2011, 09:16 am
There's no picture of the wire!

Before a wire can be used, it must be properly declared and defined.
Title: Re: Loop Back Test - Sticky?
Post by: stargazer2050 on Jan 17, 2012, 11:12 pm
Well, this explains the test but not what to do when it fails, so its really not an explanation at all
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Jan 18, 2012, 12:29 am

@stargazer2050: If you would like help or to affect a change you will have to provide more information.
Title: Re: Loop Back Test - Sticky?
Post by: athanasius on Jan 30, 2012, 08:01 pm
not even stickey

OSX 6.5.8 (fresh install)

Board 1 -- Arduino Mega Failed loopback test
Board 2 -- Arduino Mega Failed loopback test
Board 3 -- Arduino Uno Failed loopback test
Board 4 -- Arduino Uno Passed loopback test

Arduino 1.0


I have three boards which are no longer working: They were working fine at least 12 hours ago:

all three failed the loopback test. One did not even register with a usb serial connection.

This has been tried on at least 3 computers so far

any advice would be helpful
Title: Re: Loop Back Test - Sticky?
Post by: madworm on Jan 30, 2012, 09:17 pm
If all of these boards used to work at some point, I'd try analyzing what you did to them. And if you find a common 'thing' (can't think of a better word right now), stop doing that.
Title: Re: Loop Back Test - Sticky?
Post by: mmcp42 on Jan 31, 2012, 11:07 pm
just tried the instructions, just for fun
seemed clear enough to me
oh - and got the expected result

didn't seem patronising (until I read this thread!)
could be idiot-proof
trouble is they outnumber us already and they're breeding like rabbits
[/soapbox]
:)
Title: Re: Loop Back Test - Sticky?
Post by: kkinney on Feb 21, 2012, 07:51 pm
Great documentation!!!  (And I regularly read IBM mainframe docs.)
I followed the instructions and it behaved exactly as expected; a text version of ping.

I strung together some code to do the same thing.  The problem is all I get back is rectangles under the serial monitor.  Can you think of something to account for that?
Here's my code -
Quote

void setup() {
  Serial.begin(9600);
  pinMode(2, INPUT);
}

void loop() {
    if (Serial.available() > 0) {
      Serial.println(Serial.read());             
    }
  }
}




Any help would be appreciated.

Regards,
kk
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Feb 21, 2012, 08:31 pm

Great documentation!!!  (And I regularly read IBM mainframe docs.)
I followed the instructions and it behaved exactly as expected; a text version of ping.

I strung together some code to do the same thing.  The problem is all I get back is rectangles under the serial monitor.  Can you think of something to account for that?
Here's my code -
Quote

void setup() {
  Serial.begin(9600);
  pinMode(2, INPUT);
}

void loop() {
    if (Serial.available() > 0) {
      Serial.println(Serial.read());             
    }
  }
}




Any help would be appreciated.

Regards,
kk


Be sure the serial monitor is set to the same baudrate that your sketch is using (9600) in your case. The selection is done at the bottom right of the serial monitor window when it's opened.

Lefty

Title: Re: Loop Back Test - Sticky?
Post by: kkinney on Feb 23, 2012, 01:17 pm
I've set it to a matching baud rate with the similar results.

I found a port monitor and sent it a string of 'a's.  Here's what the monitor saw-
Port opened by process "javaw.exe" (PID: 6424)

Request: 2/23/2012 7:14:25 AM.52364 (+180.2188 seconds)

61 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61   aaaaaaaaaaaaaaaa
61 61 61 61 0D 0A                                 aaaa..         

Answer: 2/23/2012 7:14:25 AM.53864 (+0.0156 seconds)

39 37 0D 0A 39 37 0D 0A 39 37 0D 0A 39 37 0D 0A   97..97..97..97..
39 37 0D 0A 39 37 0D 0A 39 37 0D 0A 39 37 0D 0A   97..97..97..97..
39 37 0D 0A 39 37 0D 0A 39 37 0D 0A 39 37 0D 0A   97..97..97..97..
39 37 0D 0A 39 37 0D 0A 39 37 0D 0A 39 37 0D 0A   97..97..97..97..
39 37 0D 0A 39 37 0D 0A 39 37 0D 0A 39 37 0D 0A   97..97..97..97..
31 33 0D 0A 31 30 0D 0A                           13..10..


Ideas anyone?
Title: Re: Loop Back Test - Sticky?
Post by: PaulS on Feb 23, 2012, 04:00 pm
Perhaps a peak at an ascii table (http://www.asciitable.com/ (http://www.asciitable.com/)) might shed some light.
Title: Re: Loop Back Test - Sticky?
Post by: kkinney on Feb 24, 2012, 02:06 am
Thank you for the tip on ASCII chart. (Personally, I bleed EBCDIC.)

After seeing 'a'=97, I tried all println formats.  BYTE has been dropped, but the compiler pointed me in the right direction.  This is the code that works -
      int crap = Serial.read();
      Serial.write(crap);             


Thank you for the assist,
kk
Title: Re: Loop Back Test - Sticky?
Post by: dannycelluk on Mar 06, 2012, 05:02 pm
I recently bought a Arduino Mega 2560.

Everything appeared to be working fine to start with, I managed to blink LED's and show temperature in the serial monitor etc.

The latest thing i have tried to do was to show text on an LCD. The Text was really dull even with the POT turned up and down.

Now when i connect my Arduino to the USB cable it does not show up in the Arduino software.

Mega 2560 is selected in the board options, but the port is blanked out, as if the pc cannot see the board.

I have tried different ports and the cable is brand new, and work to start with.

I have trioed pressing the Reset button which also does nto appear to work. I have tested the voltages on the power pins and they all seem fine. neither tx or rx LED illuminate but the power LED does.

PC does not see board during loop back test

Any ideas?

Thanks

Dan
Title: Re: Loop Back Test - Sticky?
Post by: jobaum on Mar 31, 2012, 05:56 pm
My uno suddenly stoped working.. im afraid I may have touched two wires that shouldn't have while working with it last night. Power light comes on, but the other lights dont blink like they normally would when turning on and dont do anythign while trying upload to the board... I keep getting the error "programmer not responding". My computer detects the USB and so does the arduino program... but when i tried the loop test it failed to echo back the text.... have not tried another ocmputer yet, but I tried my MEGA board on the same ocmputer and it works fine...

WTF!?
Title: Re: Loop Back Test - Sticky?
Post by: madworm on Mar 31, 2012, 06:08 pm
No no, not WTF but "cause and consequence".

Your problem is easily solved by throwing some money at it (get a new one).

BTW, did you remove the chip before trying the loop-back test?
Title: Re: Loop Back Test - Sticky?
Post by: jobaum on Mar 31, 2012, 06:11 pm
haha I know I know, but spending money is last result!

and remove what chip? My arduino uno doesnt have any removable chips (that i know of).
Title: Re: Loop Back Test - Sticky?
Post by: madworm on Mar 31, 2012, 06:31 pm
So you have the all-SMD version. Tough luck.
Title: Re: Loop Back Test - Sticky?
Post by: jobaum on Mar 31, 2012, 06:56 pm
:(
Title: Re: Loop Back Test - Sticky?
Post by: istanto on Jun 27, 2012, 10:18 am
mau tanyak scrip untuk mengoneksi arduino uno atg328 gmn yaaa?
Title: Re: Loop Back Test - Sticky?
Post by: nickgammon on Jun 27, 2012, 01:29 pm
This *is* the English language part of the forum.
Title: Re: Loop Back Test - Sticky?
Post by: guy56 on Jun 30, 2012, 11:38 am
Thank you
Title: Re: Loop Back Test - Sticky?
Post by: munka on Jun 30, 2012, 10:41 pm
So what do I do if my board fails the loop back test??  When i plug my board in, nothing pops up, makes a noise, or tries to install drivers.  When I look at my device manager, I see a COM port, but its not called arduino anything (like the installation instructions say it will be).  Uploading of the blink code doesn't work.

Binary sketch size: 1,632 bytes (of a 258,048 byte maximum)
avrdude: usbdev_open(): did not find any USB device "usb"

I'm on Windows 7 64 bit
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Jul 01, 2012, 12:45 am
So what do I do if my board fails the loop back test??


=(

Which board?
Title: Re: Loop Back Test - Sticky?
Post by: gizmoDave on Aug 15, 2012, 04:57 am
loop back test shows my Uno R3 is working, but I am still getting sync error 
avrdude: stk500_getsync(): not in sync: resp=0x00
   Sketches indicate they upload but now do nothing not even blink the on-board indicator, plugging in an external LED extinguishes the on-board LED, the power indicator is on and the "L" indicator is dimly lighted??? Is my Uno now bricked?
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Aug 15, 2012, 05:42 am
plugging in an external LED extinguishes the on-board LED, the power indicator is on and the "L" indicator is dimly lighted???


With a series resistor?
Title: Re: Loop Back Test - Sticky?
Post by: gizmoDave on Aug 15, 2012, 06:04 am

plugging in an external LED extinguishes the on-board LED, the power indicator is on and the "L" indicator is dimly lighted???


With a series resistor?



Yes Led in series.
Seems I corrupted my install while attempting to add ATTiny13 support files and the loop back test  triggered something strange. 
After a clean install of arduino-1.0.1 my Uno seems to be back to normal.
Title: Re: Loop Back Test - Sticky?
Post by: smeezekitty on Aug 15, 2012, 07:23 am


plugging in an external LED extinguishes the on-board LED, the power indicator is on and the "L" indicator is dimly lighted???


With a series resistor?



Yes Led in series.
Seems I corrupted my install while attempting to add ATTiny13 support files and the loop back test  triggered something strange. 
After a clean install of arduino-1.0.1 my Uno seems to be back to normal.

Next time do not replace any files.
Title: Re: Loop Back Test - Sticky?
Post by: com64 on Sep 08, 2012, 08:02 am
Hello,

How do you read and implement item 6:

" 6. Start your favourite terminal application.  Serial Monitor will work fine."

Thank you,
Regards

com64
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Sep 08, 2012, 05:05 pm

Hello,

How do you read and implement item 6:

" 6. Start your favourite terminal application.  Serial Monitor will work fine."

Thank you,
Regards

com64


In the tools menu of the Arduino IDE there is a 'serial monitor' selection that will launch a small standalone serial monitor application that you can use to send and receive characters to an attached arduino board. Be sure you set the serial monitor's baud rate to match the baud rate you use in your running sketch on the arduino board. You can also use most any PC terminal application that you might have or obtain, and they usually have many more features on them that the arduino IDE serial monitor does not. I like brey terminal on my windows PC and there are many other free PC terminal applications avalible if you want or need something more powerful then the arduino serial monitor.

Lefty
Title: Re: Loop Back Test - Sticky?
Post by: ksp1717 on Sep 10, 2012, 10:30 pm
Hi

Thanks for the test. So here it goes. I have two Mega 2560 R3 that I have problems with.

I did the loop test.  I connected Reset to GND and TX0 to RX0 and I tried using the Serial Monitor.

For the first board, I got COM11 in my Device Manager. The L led on the board is goes on as soon as I connect it to my PC. I did not get my messages back from the board. :(

For the second board, there is no COM port in my Device Manager, the L Led on the board is on for a fraction of asecond and that too very dim. And as before I did not get my messages back.

Can any one suggest me what I should do next ???

Thanks

-ksp
Title: Re: Loop Back Test - Sticky?
Post by: refhwengr on Sep 12, 2012, 10:54 pm
I have an UNO R3 running on an older dell laptop, windows 2000.  The monitor results are perplexing.  I input a string 123456789_123456789 but it only repeats back the first eight characters.  12345678 , the rest of the string is missing.  I can see the TX and RX LEDs blinking but not getting a full echo.  I also noted that I have to close the monitor window and reopen it to try sending another message.  If I do not perform that interum step, there is no echo at all.  Any thoughts on what the indications mean, thanks for the help.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Sep 12, 2012, 11:28 pm
For the first board, I got COM11 in my Device Manager. The L led on the board is goes on as soon as I connect it to my PC. I did not get my messages back from the board. :(

For the second board, there is no COM port in my Device Manager, the L Led on the board is on for a fraction of asecond and that too very dim. And as before I did not get my messages back.

Can any one suggest me what I should do next ???


For both boards there is a slight possibility that reflashing the ATmega16U2 will bring them back to life.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Sep 12, 2012, 11:31 pm
I have an UNO R3 running on an older dell laptop, windows 2000.  I input a string 123456789_123456789 but it only repeats back the first eight characters.  12345678 , the rest of the string is missing.


Ensure the driver is up-to-date.  Try a different USB cable.

Anything getting hot?
Title: Re: Loop Back Test - Sticky?
Post by: ksp1717 on Sep 15, 2012, 11:22 pm
Hi

I have tried reflashing them using an Arduino Uno as an ISP. I used the default stk500v2 hex file in the hardware->arduino->bootloaders->stk500v2. On both boards at the end I got the content mismatch error. I did some research online and found that the process works even if one gets that error. But nothing happened.  :~

So I tried with another version of bootloader file from https://github.com/arduino/Arduino-stk500v2-bootloader/tree/master/goodHexFiles (https://github.com/arduino/Arduino-stk500v2-bootloader/tree/master/goodHexFiles). I got the same content mismatch error from avrdude and nothing happened when I try to upload a sketch.

I am still unable to upload any sketches to my boards even after reflashing them.

Any more ideas on atleast what the problem might be ?

Thanks

--ksp
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Sep 16, 2012, 12:38 am

The ATmega16U2 does not get a "bootloader".  It gets a "firmware".  You're trying to upload the wrong file.
Title: Re: Loop Back Test - Sticky?
Post by: proaudio on Oct 08, 2012, 05:45 pm
Hello, I did this procedure with my Arduino Mega board and nothing different happens. The problem is no usb communication and the two leds RX and TX still on (half power). Here is a little video to show you. Thank very much

http://www.youtube.com/watch?v=EIg7wcW2SUw

Title: Re: Loop Back Test - Sticky?
Post by: CrossRoads on Oct 08, 2012, 06:38 pm
You're not following the loopback test - I don't see Rx & Tx connected for instance.

So what happened leading up to this?   12V get applied to something it shouldn't have?
Sort of looks like a dead (or misprogrammed?) 16U2 device, it drives the Rx/Tx LEDs, and a good '2560, it drives the L LED. 
You could try to program both parts thru their ICSP connectors and see if they are still alive.
Title: Re: Loop Back Test - Sticky?
Post by: proaudio on Oct 08, 2012, 06:58 pm
Thank you for your answer. I did the connections from Rx/Tx and RESET to GND and nothing changes. The pc not recognize it when I connect it to USB (it was COM3)... my Arduino UNO works perfect with the same cable and same USB port (and all the time they worked in this USB port).
I was working with I2C communication between them with power supplies separated... I don't remember something suspicious.
I think ICSP is my only chance,( but I don't know what I need). Thank you and regards
Title: Re: Loop Back Test - Sticky?
Post by: CrossRoads on Oct 08, 2012, 07:06 pm
Easiest way to program via ICSP is with Atmel AVR ISP MKii, $34 from mouser.com.
Driver can be found in an IDE folder.

You can also use the Uno as a programmer. Look at NickGammon's solution:
http://www.gammon.com.au/forum/?id=11635
Title: Re: Loop Back Test - Sticky?
Post by: SnowLeopard on Nov 19, 2012, 08:10 pm
What does it mean if the loopback test works without connecting RST to GND?
Like many other people, I have a board (Nano 3.0) which suddenly ceased to work.  When I first received it, it had no bootloader so I burnt one using a Mega2560 without any problems.  Over the course of a couple days, I used the Nano to test a Nokia LCD screen, some temperature sensors, and a few other things all problem-free... then one day, when I plugged it in to try something else, and it seemed have to lost it's bootloader.  I've tried to reburn the bootloader unsuccessfully several times, getting the same avrdude verification error which seems to indicate fried flash memory.
The loopback test works and everything sent gets echoed back, even when RST is not connected to GND, which gives me the impression the reset button is stuck on or shorted somehow... I've examined the board with a magnifier and do not see any shorts.
Anything else I should try?
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Nov 19, 2012, 08:28 pm

What does it mean if the loopback test works without connecting RST to GND?
Like many other people, I have a board (Nano 3.0) which suddenly ceased to work.  When I first received it, it had no bootloader so I burnt one using a Mega2560 without any problems.  Over the course of a couple days, I used the Nano to test a Nokia LCD screen, some temperature sensors, and a few other things all problem-free... then one day, when I plugged it in to try something else, and it seemed have to lost it's bootloader.  I've tried to reburn the bootloader unsuccessfully several times, getting the same avrdude verification error which seems to indicate fried flash memory.
The loopback test works and everything sent gets echoed back, even when RST is not connected to GND, which gives me the impression the reset button is stuck on or shorted somehow... I've examined the board with a magnifier and do not see any shorts.
Anything else I should try?



The reason for the reset to ground jumper is just insurance against if an existing program running in the AVR chip is utilizing pins 0 and 1 and could therefore cause problems with the loop back being hardwired between pins 0 and 1. The reset to ground causes the AVR to freeze and default all I/O pins to input mode so it can have no electrical effect on the pins 0 and 1 jumper installed for the test to operate. So the fact that the tests works OK even without the ground on reset, just means the USB serial converter chip is functional, and that is all it means.

Lefty
Title: Re: Loop Back Test - Sticky?
Post by: veimox on Dec 11, 2012, 01:13 pm
I have an Arduino Mega and it was working correctly until 1 day ago. I don't remember if I did a short or something but the problem is that now does not work. If checked Drivers, the usb laptop and the cable so I'm pretty sure is a board problem.

The problem is that when I connect the board to the USB there is no communication. I connect it and led "L" blink twice (so it is powered) and no more, TX and RX are like dead. I have tried to follow the "Loop-Back Test Instructions" and I don't know if I doing it correctly for Arduino Mega. (" http://arduino.cc/forum/index.php/topic,73748.0.html ")

In 3, "Connect Jumper from RESET to GROUND" is the same to maintain button reset pressed?.

And number 4, jumper from TX to RX, I have to do it in all of the Arduino Mega TX and RX's pins?

Thanks!
Title: Re: Loop Back Test - Sticky?
Post by: PaulS on Dec 11, 2012, 01:21 pm
Quote
In 3, "Connect Jumper from RESET to GROUND" is the same to maintain button reset pressed?.

Yes.

Quote
And number 4, jumper from TX to RX, I have to do it in all of the Arduino Mega TX and RX's pins?

No. Only pins 0 and 1 are connected to the USB to serial converter, which is what the loopback test is testing.
Title: Re: Loop Back Test - Sticky?
Post by: veimox on Dec 11, 2012, 01:26 pm
Ok, so there is no detection in Windows, Mac or Linux. What should I do now? Is there a chip responsible of communication that I can change or is easier to change the board?

Thanks for the fast answer!
Title: Re: Loop Back Test - Sticky?
Post by: PaulS on Dec 11, 2012, 01:34 pm
Quote
Is there a chip responsible of communication

Yes. Right next to the USB connector.

Quote
that I can change

Depends on your ability with a soldering iron. It's a surface mount chip - beyond my skills to replace. (Software is so much easier.)

Quote
or is easier to change the board?

Sure. What the heck, it's only money.
Title: Re: Loop Back Test - Sticky?
Post by: veimox on Dec 11, 2012, 01:40 pm
I think I could change the chip but, is possible that I change it and it will still no working? I mean, if there was a short the atmel can also be damaged, isn't it?
Title: Re: Loop Back Test - Sticky?
Post by: nickgammon on Dec 11, 2012, 09:27 pm
If you program it via the ISP interface (the 6 pins near the reset button) you may be able to keep using it, just without the USB interface (assuming that is what is wrong). You can do this with a $10 to $20 ISP programmer device, or just use another Arduino board as a programmer (look up Arduino as ISP).
Title: Re: Loop Back Test - Sticky?
Post by: nickgammon on Dec 11, 2012, 09:29 pm
If you have a Uno or similar lying around you can use my "chip detector" sketch to see if the main processor is OK:

http://www.gammon.com.au/forum/?id=11633

Example hook-up:

(http://www.gammon.com.au/images/Arduino/Atmega_Chip_Detector4.jpg)

You don't have to use the special cable, you can use jumper wires to the correct pins.
Title: Re: Loop Back Test - Sticky?
Post by: koolasg on Dec 20, 2012, 04:52 am


MY UNO WAS WORKING GREAT .. BUT
SUDDENLY IT IS NOT RECOGNIZED BY MY PC...
I M HAVING TROUBLE WITH MY UNO R3. PC NOT DETECTS IT , I.E "NO DEVICE FOUND PROBLEM"
I CHANGED MY CABLE , TRIED ON OTHER PC BUT NO COMPORT , OR NO "NEW DEVICE FOUND"
WHAT IS THE PROBLEM ?

I HAVE DONE "Loop-Back Test"
! BUT GOD KNOWS WHY NO DEVICE DETECTED IN PC ....... HELP ME GUYS'


ADVANCE THANKS !
Title: Re: Loop Back Test - Sticky?
Post by: smeezekitty on Dec 20, 2012, 05:42 am



MY UNO WAS WORKING GREAT .. BUT
SUDDENLY IT IS NOT RECOGNIZED BY MY PC...
I M HAVING TROUBLE WITH MY UNO R3. PC NOT DETECTS IT , I.E "NO DEVICE FOUND PROBLEM"
I CHANGED MY CABLE , TRIED ON OTHER PC BUT NO COMPORT , OR NO "NEW DEVICE FOUND"
WHAT IS THE PROBLEM ?

I HAVE DONE "Loop-Back Test"
! BUT GOD KNOWS WHY NO DEVICE DETECTED IN PC ....... HELP ME GUYS'


ADVANCE THANKS !

Pretty much the causes are fried or misprogrammed USB interface chip.
Title: Re: Loop Back Test - Sticky?
Post by: PaulS on Dec 20, 2012, 11:59 am
Quote
Pretty much the causes are fried or misprogrammed USB interface chip.

Could be something you did to the PC, too. I mean, after all, you've got the shift key sticking pretty badly.
Title: Re: Loop Back Test - Sticky?
Post by: jrburke99 on Mar 11, 2013, 04:21 pm
When I do a loopback test, the TX and RX lights both flash at the same time when I type, but I get nothing on the screen in the Serial Monitor. Also tried with PuTTY, with same results. This behavior is the same on 2 different machines. The board works on one and not the other, so that is why I am trying the loopback test. Seems odd it does not work on EITHER machine! The drivers seem to work, and the board is recognized just fine on both machines.

And if I upload a sketch to do a Serial.println("Hello!");, that works just fine, and I see the test come up in the Serial Monitor.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Mar 11, 2013, 06:37 pm

Is your post above about the same problem you reported here...
http://arduino.cc/forum/index.php/topic,153580.msg1151727.html#msg1151727
Title: Re: Loop Back Test - Sticky?
Post by: jrburke99 on Mar 12, 2013, 02:26 pm
Yes and no. Same board, but this happens even on my machine that works perfectly fine. So wondering why the loopback does not work even when everything else seems to work fine. I can see both the TX and RX lights flash when I type, I can upload sketches and they work fine, and if my sketch prints back to the serial monitor, I see that all just fine as well.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Mar 12, 2013, 07:18 pm
Quote
And if I upload a sketch to do a Serial.println("Hello!");, that works just fine, and I see the test come up in the Serial Monitor.


And in PuTTY?

Assuming everything is working the way you described, the only thing left is the Windows kernel driver.

Is the Prolific PL-2303HX USB driver provided by Microsoft or Prolific?  (You will have to check the version stamp on the .SYS file.)
Title: Re: Loop Back Test - Sticky?
Post by: jrburke99 on Mar 12, 2013, 09:42 pm
The driver was downloaded directly from the Prolific website. In PuTTY, I get the same thing where I see nothing when I type, although I see the TX and RX lights on the board blink when I type.

Also, I have gotten this to work on the Win7 box, but only by using VirtualBox with a WinXP OS, and creating a COM port in the virtual machine that maps back to the one in Win7 that is created by Prolific. If I simply pass the USB device through, it shows up fine in the WinXP control Panel, but I get the same other problems.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Mar 13, 2013, 12:10 am
The driver was downloaded directly from the Prolific website.


That doesn't mean anything.  The Arduino Uno driver is a good example.  It can be downloaded directly from this site but the kernel driver is Microsoft's.

Quote
In PuTTY, I get the same thing where I see nothing when I type, although I see the TX and RX lights on the board blink when I type.


As far as I can tell, that proves the kernel driver is the culprit.
Title: Re: Loop Back Test - Sticky?
Post by: jrburke99 on Mar 13, 2013, 03:17 pm
Great. So if the kernel driver is the most likely culprit, how can I remedy that?
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Mar 13, 2013, 06:42 pm

1. Use Google to determine if others have similar problems (my diagnosis could be wrong; you may find a solution).

2. Search the vendor's site for a newer version.

3. Pester the vendor for a bugfix.

4. Test older versions.

5. Determine if the converter is similar or identical to other converters and use the driver from the other converter (this one entails modifying or creating an INF file).

6. Stop wasting your time and buy a board from a reputable vendor.
Title: Re: Loop Back Test - Sticky?
Post by: hilaryramirez on Mar 29, 2013, 07:28 pm
Are the instructions basically the same for a mac?
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Mar 29, 2013, 08:05 pm

Yes.
Title: Re: Loop Back Test - Sticky?
Post by: C2 on May 08, 2013, 09:26 pm
Will this test verify the operation of an FTDI board/cable without an arduino, just by jumpering the RX to TX lines?
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on May 08, 2013, 10:21 pm

Yes.
Title: Re: Loop Back Test - Sticky?
Post by: terryking228 on Jun 14, 2013, 03:50 pm
Hi,
Would it be good to include a photo of an Arduino with the two jumpers clearly in position?

I'd need to find some Red or Yellow wire....
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Jun 16, 2013, 07:07 am

Sounds good to me.  If you make an image, please try to keep it less than or equal to 320 by 240.
Title: Re: Loop Back Test - Sticky?
Post by: terryking228 on Jun 17, 2013, 04:17 pm
Hi CodingB, I'll shoot it soon...
Title: Re: Loop Back Test - Sticky?
Post by: abpccpba on Jun 26, 2013, 10:28 pm
Work well.  :D
Title: Re: Loop Back Test - Sticky?
Post by: pwhalley on Jul 08, 2013, 01:55 am
These directions don't appear to be universally applicable - specifically to the Micro and Leonardo correct?  If not how to?

Peter
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Jul 08, 2013, 02:08 am
These directions don't appear to be universally applicable - specifically to the Micro and Leonardo correct?


They are universally applicable to boards that have USB-to-serial converters.

The instructions will not work for a Micro or Leonardo.

Quote
If not how to?


How to what?
Title: Re: Loop Back Test - Sticky?
Post by: retrolefty on Sep 11, 2013, 05:50 pm

These directions don't appear to be universally applicable - specifically to the Micro and Leonardo correct?  If not how to?

Peter


The sticky test was developed to be able to test just the functionality of a on board USB serial converter chip, independently of the AVR controller chip being used on the board, for boards that have separate USB and controller chips. On boards that use a AVR controller chip that have built in USB connectivity there is no need for this test.

Lefty
Title: Re: Loop Back Test - Sticky?
Post by: arteduino on Dec 05, 2013, 09:10 pm
I did it. It worked (eecchhoo)
I`m having a: "avrdude: stk500_recv(): programmer is not responding" with a NKC Freeduino V2.2 on Ubuntu Studio 13.04
Thanks for the tip. Now I know my serial rig over USB is working.
Best Regards
Jose Angel Mora
Title: Re: Loop Back Test - Sticky?
Post by: barrybloomfield on Dec 27, 2013, 04:13 pm
thanks for the info
Title: Re: Loop Back Test - Sticky?
Post by: tarnall on Feb 22, 2014, 10:52 pm
Did not understand setup #7 "Connect the terminal application to the serial port of your board"  I was using Sketch.....Serial Monitor.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Feb 22, 2014, 10:59 pm

Serial Monitor is a terminal application.  It will work fine for the test.
Title: Re: Loop Back Test - Sticky?
Post by: Jacknet on Mar 11, 2014, 11:26 pm
Is there a loop back test for the Arduino Mega 2560? I don't see a reset pin on it. My tx1 and rx0 are on two different sockets. Unfortunately rx0 is on the ftdi that I use to connect to my PC.

"Start your favourite terminal application.  Serial Monitor will work fine."
What would be a terminal application and how do I monitor the Serial Monitor on the Mega 2560?

I also have a Arduino Uno that I uploaded a sketch to and I ran fine so I'm assuming it's working ok. Does this loop test tell me more about my Uno that I would like to know? I have a reset pin and a tx1 and rx0 on the Digital pins. But again, not to sound stupid but what would be a terminal program and how do you hook up a serial port to test with.
Title: Re: Loop Back Test - Sticky?
Post by: smeezekitty on Mar 12, 2014, 12:34 am
Quote
Unfortunately rx0 is on the ftdi that I use to connect to my PC.

That's the point
Quote

I also have a Arduino Uno that I uploaded a sketch to and I ran fine so I'm assuming it's working ok. Does this loop test tell me more about my Uno that I would like to know? I have a reset pin and a tx1 and rx0 on the Digital pins. But again, not to sound stupid but what would be a terminal program and how do you hook up a serial port to test with.

The loopback test is to verify operation of the USB/serial chip. If it works there is no need for it
Title: Re: Loop Back Test - Sticky?
Post by: Jacknet on Mar 12, 2014, 01:11 am

Quote
Unfortunately rx0 is on the ftdi that I use to connect to my PC.

That's the point
Quote

Are you referring to a Mega 2560 board?
Title: Re: Loop Back Test - Sticky?
Post by: piaopiaokai on May 10, 2014, 04:34 am
According  to the instruction, my PC even  cannot connect my leonardo device . my PC can not find the serial port .PC have no sound(my PC speaker turn on)
Title: Re: Loop Back Test - Sticky?
Post by: ism_syed on May 24, 2014, 02:45 pm
its not working ..what should  do?
Title: Re: Loop Back Test - Sticky?
Post by: micjarda on Jan 30, 2015, 02:07 pm
It would help if someone please with these six questions?

1. What do you sound? 
2. Where do I find the computer system protocol?
3. What terminal do you mean Arduino IDE? 
4. How do I connect the terminal application to the serial port on my Arduino? 
5. I do not know why but the information that sends me not go back?
6. What is the end application?
Title: Re: Loop Back Test - Sticky?
Post by: micjarda on Jan 31, 2015, 09:08 am
Excuse me for grammar, I'm from Czech Republic and I am fourteen years old.
Title: Re: Loop Back Test - Sticky?
Post by: micjarda on Feb 02, 2015, 09:01 am
So now someone please answer! ;)
Title: Re: Loop Back Test - Sticky?
Post by: ShooterBobSC on Apr 08, 2015, 02:08 am
does not help with Mini 328 board.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Apr 08, 2015, 03:06 am

Huh?

Title: Re: Loop Back Test - Sticky?
Post by: Amith_gowda on Jul 22, 2015, 05:46 pm
Hello there,
I'm a beginner in arduimo development so please bear with me! I would love to know what you mean by "launch your favourite terminal application".
Thank you
Title: Re: Loop Back Test - Sticky?
Post by: MAS3 on Jul 22, 2015, 06:03 pm
You need a PC program to communicate over the serial line.
These programs are called terminal programs (or application).

Older Windows versions came with hyperterminal.
But there's a lot of these applications around, and each has its own advantages and disadvantages.
Title: Re: Loop Back Test - Sticky?
Post by: kenneth-pritchard on Sep 26, 2015, 07:10 pm
HOW DO YOU GET THE SERIAL MONITOR?
Title: Re: Loop Back Test - Sticky?
Post by: MAS3 on Sep 26, 2015, 07:45 pm
Hi and welcome.

Certainly not by SHOUTING at it, that's just rude.

Open the Arduino IDE.
On the right , just above the edit screen you'll see an icon.
If you hover over it, a text will appear telling you that that is a way to open the serial monitor (click it).
You can also go to the menu, tools and select serial monitor from there.
Or press ctrl+shift+m .
Plenty of ways to get there i'd say (this is all valid for the windows version of the IDE, i don't know about other versions but i suspect some of the above mentioned will be very similar).
Title: Re: Loop Back Test - Sticky?
Post by: vaclav on Jan 17, 2016, 01:55 am
Working serial connection between Arduino serial port and PC is demonstrated by flashing of both RX and TX  LEDs during ANY program "Upload".

The physical RX path can also be verified by using and running Examples Basic BareMinimum and monitor.
 
Just type in random series of characters - using  PC keyboard "repeat" feature and than pres "Send"  or just key in "Enter".

Flashing "RX" LED indicates good RX connection and is a good indicator that TX works also.
Setting the baud rate to 300 bauds makes the RX flashing more pronounced during this simple verification test.


Software remote loopback test (monitor as a source and Arduino as a remote destination) can be implemented by echoing ( using Serial ) the characters typed into monitor "send" field back to the monitor "print" field.
Observing both LED's will verify the connection. 

Software remote test  "sketch" available upon request. 

Title: Re: Loop Back Test - Sticky?
Post by: jefedelosjefes on Feb 02, 2016, 11:59 pm
So my Arduino Uno R3 board failed the test and will not execute the program that used to be on it, and does not allow me to upload any new program; returns "avrdude: stk500_recv(): programmer is not responding".  The "ON" light is on and the "L" LED stays solid on all of the time.  Correct voltage comes out of the 5V pin.  Does this mean that the processor is dead and I should buy a new board?  Not sure what the next test I should run is.
Title: Re: Loop Back Test - Sticky?
Post by: MAS3 on Feb 03, 2016, 01:04 am
Hi and welcome.

The loopback test doesn't test the controller ("processor"), it tests the USB to serial converter without any interaction of that controller.
That's why you need to keep the reset active during the test.

So if you do the loopback test and it fails, you can assume the USB to serial converter chip is dead.
It doesn't tell you anything about the controller (so that also means it could still have died during the event causing this).
There's other ways to program the controller, but that's a bit more advanced and you need something to replace the USB to serial converter (perhaps another Arduino board).
Or ultimately use an external programmer.
Title: Re: Loop Back Test - Sticky?
Post by: jbernhardt on Feb 12, 2016, 11:27 pm
can't do this test if the computer can't talk to the uno.
Title: Re: Loop Back Test - Sticky?
Post by: lone182 on Mar 22, 2016, 08:46 pm
could you please show which port should i connect the jumpers on a arduino mega 2560?
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Mar 22, 2016, 08:53 pm

I assume instead of "port" you mean "pin".  In which case you will need to make two connections.  The complete instructions are here...
http://forum.arduino.cc/index.php?topic=73748.0 (http://forum.arduino.cc/index.php?topic=73748.0)

Title: Re: Loop Back Test - Sticky?
Post by: CrossRoads on Mar 22, 2016, 08:57 pm
D0 & D1.
Title: Re: Loop Back Test - Sticky?
Post by: 0xSAM on Jun 02, 2016, 05:44 pm
Good write up... thanks for the details
Title: Re: Loop Back Test - Sticky?
Post by: jrpjim on Nov 05, 2016, 12:15 pm
New to Arduino and programming first time user so the direction

6. Start your favourite terminal application.  Serial Monitor will work fine.

does not tell me what I should do as I do not have a favourite Terminal application and don't know what Serial Monitor is.
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Nov 05, 2016, 06:43 pm

I am sorry to hear you are struggling with Google.  This should help...
https://www.google.com/search?q=arduino+serial+monitor (https://www.google.com/search?q=arduino+serial+monitor)

Title: Re: Loop Back Test - Sticky?
Post by: Mocivnik on Nov 15, 2016, 01:00 pm
Thanks for the whole process, but I'm currently stuck at step nr. 7. I don't really understand, what do you mean by "Connect the terminal application to the serial port for your board."

How are we supposed to do that?
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Nov 15, 2016, 05:02 pm

(http://forum.arduino.cc/index.php?action=dlattach;topic=67509.0;attach=187162;image;)

Title: Re: Loop Back Test - Sticky?
Post by: Mocivnik on Nov 15, 2016, 09:02 pm
Hmm, that's it? Okay, got connected. But still, wasn't able to do anything actually.

Considering changing 1. Atmel and then 2. FTDI.
Title: Re: Loop Back Test - Sticky?
Post by: MAS3 on Nov 15, 2016, 11:34 pm
If you see your typed texts in terminal, you do not need to change the FTDI.
That's what this thread is all about: figuring out whether your USB/serial chip (for you FTDI) works or not.
If you do not see anything, suspect FTDI and anything it depends on (assuming you did all steps correctly).
The latter doesn't mean Atmel is OK.
Title: Re: Loop Back Test - Sticky?
Post by: martymarty on Mar 07, 2017, 08:46 am
As a novice to Arduino I have the following questions regarding:
http://forum.arduino.cc/index.php?topic=73748.0
< Loop-Back Test Instructions >

QUESTION
      " 6. Start your favourite terminal application.  Serial Monitor will work fine."

Q1:does (6) mean:  Clk on Serial Monitor icon top, right hand edge of Arduino IDE screen?
-------------------------------------------------- 
      "7. Connect the terminal application to the serial port for your board. 

Q2:does (7) mean: perform the procedure described in (8)"Send data..." ;
 the data should be echoed back to the Serial Monitor from the Arduino UNO   



marty
email:  hawkeye@013net.net     
Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Mar 07, 2017, 09:04 am

Do not cross-post.  Other thread removed.

Title: Re: Loop Back Test - Sticky?
Post by: Coding Badly on Mar 07, 2017, 09:09 am
Q1:does (6) mean:  Clk on Serial Monitor icon top, right hand edge of Arduino IDE screen?
Yes.

Quote
Q2:does (7) mean: perform the procedure described in (8)"Send data..." ;
 the data should be echoed back to the Serial Monitor from the Arduino UNO   
No.  When using Serial Monitor you have to select the serial port before opening Serial Monitor.  In the IDE click Tools then Port then the serial port associated with your board.

Title: Re: Loop Back Test - Sticky?
Post by: bkmtech on Apr 23, 2017, 02:28 am
Couldn't you just disconnect the Serial Converter and loop back right there.
Title: Re: Loop Back Test - Sticky?
Post by: larryd on Apr 23, 2017, 02:32 am
What happened when you tried?

"Serial Converter"
What converter?


.
Title: Re: Loop Back Test - Sticky?
Post by: ballscrewbob on Apr 23, 2017, 02:41 am
+1 for 2