Check my circuit - forum etiquette?


I couldn't find a forum etiquette guide so I thought I'd ask rather than causing offence.

I'm designing my own atmega32u4 based board to allow me to embed arduino like functionallity into a bigger project but I'm still very new at this.

I've a circuit designed (for 'designed', read 'copied and simplified') and I think it's right but would love someone who knows a bit more than me to give it the once over. Is posting something like that OK?

A bit more information, I don't need full arduino pin out compatibility, just the ability to read two switches. I intend to use LUFA at this stage but want to maximise my chances of being compatible with the Leonardo bootloader when it's released with the full understanding that this is impossible to guarantee until the final version is release but fingers crossed.



Is fine, post away.

Much obliged

I’ve uploaded an image of the circuit, I can upload the original Eagle files if that would be handier?

Some additional information. I’ve copied the design from Waiting For Friday’s dev board (, stripped of the bits I thought I didn’t need and rewired for the USB header I’m using for testing, it’ll eventually be hardwired to a USB hub IC.

The eventual board will be wired up to external inputs via two optocouplers, the switches are just for testing at this stage. I’ve still working on the PCB design, much editing based on my new understanding of capacitors and noise protection.



Need a 10K pullup from reset to +5. Need a 100nF cap from Aref to Gnd.

How are you programming?

Many thanks

CrossRoads: How are you programming?

How hard can it be :)

I haven't written in C++ for a good while, all C# these days but hopefully shouldn't be too different (famous last words).

I'm not looking to do anything two special, just read whether a number of pins (between 1 and 4 depending on deployment) are high or low and report this via a generic USB HID. I'm hoping to be able to use the examples with minor tweaking.

Thanks again.


I think CrossRoads meant how are you programming your setup, is it through the bootloader or do you have a programmer. This is because of the need or otherwise for an auto reset circuit.

Exactly, how are you downloading your code?

:blush: Doh! I thought it was just bad grammar.

I'm was intending to use a programmer (USBTinyISP) but now you bring it up, if Leonardo is released and the board is code compatible then it could be useful to be able to use the Arduino IDE so may be worth revisiting.


There's a couple of Leonardo code based boards out already - fm has a Uno sized board, I did a smaller one that is more like a Promini and added a uSD socket as well . Arduino seems to be behind the curve on releasing hardware.