atmega32u drops ubs and acts weird.

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sean green

Mar 25, 2020, 3:47:38 AM3/25/20
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I have an atmega32u2 like so
MCU          = atmega32u2
ARCH         = AVR8
F_CPU        = 8000000
F_USB        = $(F_CPU)

and also a 16u2 with
MCU          = atmega16u2
ARCH         = AVR8
F_CPU        = 16000000
F_USB        = $(F_CPU)

I though it was my hardware but it IO have two boards now doing the same thing. The same code (asjusted for 32u4 / 16 clock)is working great on an 32u4.

What I see is... The USB takes about 8 seconds to enumerate and when it is working no payload data shows up expect maybe one every 5 seconds but not constant. It occasionally drops the usb also. What types of thing should I be looking at here? Both of my u2's are running on preassembled devs board (not the same kind).

Dean Camera

Mar 28, 2020, 11:01:50 PM3/28/20
to, sean green

Hi Sean,

Oh wow, the Minimus. Haven't thought about that board in years. Neat that people are still using them.

Not sure what the issue is from that description. What code are you running on the board? All I can think of would be something delaying the main USB task which would cause the USB connection to go unstable. Do the included LUFA demos work properly on the same boards? Can you show your application code somewhere so I can take a look?

- Dean

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Mar 29, 2020, 8:52:51 AM3/29/20
to LUFA Library Support List
So working with it further, I noticed it was only 8MHz and I needed 12 or greater for what I wanted to do. I swapped out the clock and the problem is gone now. Maybe 8 was too slow? Could also be the caps I guess.
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