16U2 Tx/Rx LEDs stay ON sometimes

An advanced Arduino-compatible board with ATmega1284P and ATmega32u2 MCUs for experienced users. More RAM than a Mega, but in a convenient Uno-style form factor. [Product page]
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hiduino
Posts: 12
Joined: Thu Aug 29, 2013 2:17 pm

16U2 Tx/Rx LEDs stay ON sometimes

Post by hiduino » Thu Aug 29, 2013 2:45 pm

I have been having some minor power up issues with my 22.1184MHz board. When plugging in the USB the Tx and Rx LEDs stay ON. They never turn off. Uploads work fine and board functions okay. After re-pluging again a few times the LEDs seem to be working normally. It is intermittent and sometimes the LEDs stay ON again.

Hitting the 16U2 reset button seems to clear the LEDs and they function normally with Tx/Rx data. So it seems the 16U2 may not be powering up properly?

feilipu
Posts: 52
Joined: Fri Jul 19, 2013 6:17 am

Re: 16U2 Tx/Rx LEDs stay ON sometimes

Post by feilipu » Thu Aug 29, 2013 3:12 pm

hiduino,

I've noticed this effect with my platform occasionally too.
I'm using Ubuntu 12.04, 64 bit.

The LEDs turned on indicates an error in USB enumeration.

The 32U2 sometimes doesn't enumerate properly, or it has enumerated oddly.
It happens occasionally when I've been driving the 1284P SPI bus with my AVRISP2, but I'm fairly certain this is just a coincidence. I've been putting it down to an interplay between the USB implementations of Linux and LUFA.

Another effect that I notice is that resetting (via reset button) the 32U2 doesn't generate a re-enumeration. The device actually needs to be unplugged and re-plugged before it will reconnect properly.

There may be an issue with our U2duino (renamed Benito) code from LUFA. This specific (old) project was not well maintained, although it does rely on the standard well supported and maintained LUFA code base. But, the actual code for U2duino looks very straight forward. I can't see anything obvious.

Soon as Dean finalises his 010913 LUFA release, I'll be looking at combining his USBSerial project together with his AVRISP code, to create a solution with combined functions, that has separate enumeration for the serial port and the programming port. Then, we have something special!

hiduino
Posts: 12
Joined: Thu Aug 29, 2013 2:17 pm

Re: 16U2 Tx/Rx LEDs stay ON sometimes

Post by hiduino » Thu Aug 29, 2013 8:45 pm

Interesting, when I get the stuck LEDs it still enumerated okay to my Windows XP platform. I can still upload code without issues. Hitting the 16U2 reset button does re-enumerate on my Windows XP platform and clears out the LEDs.

feilipu
Posts: 52
Joined: Fri Jul 19, 2013 6:17 am

Re: 16U2 Tx/Rx LEDs stay ON sometimes

Post by feilipu » Sat Aug 31, 2013 9:07 pm

That sounds like a win for WinXP vs. Linux.

Seriously though, I'll post the error codes for 32u2 DFU and Benito in the user manual soon. The interested can look into Dean's LUFA code as there are no changes.

P.

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