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Topic: Loop Back Test - Sticky? (Read 35 times) previous topic - next topic

Coding Badly


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?

newbee234

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!

Coding Badly

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.

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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".

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It is not mentioned anywhere on the web site!


Of course it is.  Search for the Power section...
http://arduino.cc/en/Main/ArduinoBoardUno

newbee234

Thanks for the answer.

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

Newbe -- just finding my way!

Coding Badly

#14
Aug 04, 2011, 03:19 am Last Edit: Aug 05, 2011, 09:21 am by Coding Badly Reason: 1
Which instructions are better?  Set #1...

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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...

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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


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