Improvements to ATmega32U4 board

[frank26080115]

Hi Limor

I have some improvements you should consider for the ATmega32U4.

First, why is the reset pin not broken out?

The timeout on the bootloader is annoying. It seems like you already dedicated PE6 to some LED, you can give this pin double purpose by adding a tiny push button that acts as a bootloader activation button. To enter the bootloader, hold down that button while releasing reset. If the PE6 button is not held upon reset, the bootloader will skip right to application code. I've done this modification to my Teensy++ already, it works like a charm and is much better than having the user wait 10 seconds on every reset.

The button will be open circuit in all other cases, thus you are not taking away any functionality away, only adding a more convenient bootloader.

[adafruit]

Hi Limor

I have some improvements you should consider for the ATmega32U4.

First, why is the reset pin not broken out?

it is, its on the 6-pin ICSP header

The timeout on the bootloader is annoying. It seems like you already dedicated PE6 to some LED, you can give this pin double purpose by adding a tiny push button that acts as a bootloader activation button. To enter the bootloader, hold down that button while releasing reset. If the PE6 button is not held upon reset, the bootloader will skip right to application code. I've done this modification to my Teensy++ already, it works like a charm and is much better than having the user wait 10 seconds on every reset.

The button will be open circuit in all other cases, thus you are not taking away any functionality away, only adding a more convenient bootloader.

we decided to go this route for now. you can always remove the bootloader.

[frank26080115]

it is, its on the 6-pin ICSP header

I know but I think some others may appreciate being able to access it from another pin along the edge of the board. For example, somebody might want to panel-mount a reset switch. (I know this person can probably use a ribbon cable to the ISP header instead, but for my argument, I'm assuming this person does not want to do that)

Anyways, just some suggestions if you ever plan on making a version 2

[adafruit]

we'll think about it!

[abqlewis]

I wasn't going to say anything, but as long as someone else brought it up...

I don't think of this as an improvement to the current ATmega32u4 board, (the original is so unsuccessful! ) I think of this as just something to think about when you layout a breakout board for the future ATXMega1024u32 or whatever.

I like the breakout board+ because I can cut up a $2 protoboard, and for little more than the price of the headers, I can make 4-5 easy "shields". As a result, I have a growing collection of little projects or utility circuits. But this gets a little harder when I need the RST pin, because the holes for the 6-pin ICSP header are not aligned on the same grid as the DIP headers. For now, I just drill out or cut off the end of the board, and wire in a single pin jumper or header on the rare times I need RST, but it would be cool if they were aligned.

Like I said, just FYI