Loop Back Test - Sticky?

[PaulS]

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.

[jrburke99]

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.

[Coding Badly]

Is your post above about the same problem you reported here...
http://arduino.cc/forum/index.php/topic,153580.msg1151727.html#msg1151727

[jrburke99]

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.

[Coding Badly]

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.)

[jrburke99]

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.

[Coding Badly]

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.

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.

[jrburke99]

Great. So if the kernel driver is the most likely culprit, how can I remedy that?

[Coding Badly]

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.

[hilaryramirez]

Are the instructions basically the same for a mac?

[Coding Badly]

Yes.

[C2]

Will this test verify the operation of an FTDI board/cable without an arduino, just by jumpering the RX to TX lines?

[Coding Badly]

Yes.

[terryking228]

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....

[Coding Badly]

Sounds good to me.  If you make an image, please try to keep it less than or equal to 320 by 240.