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USB IO

This is the documentation page for the USBbigmultio PCB.

overview

The USBbigmultio PCB has an USB connector and two 20-pin IO connectors. The brains of the PCB is an ATmega32U4 chip.

pinout

20 Pin connector SV1 is connected as follows

1	GND
2	GND
3	PB0
4	PB1
5	PB2
6	PB3
7	PB4
8	PB5
9	PB6
10	PB7
11	PD0
12	DP1
13	PD2
14	PD3
15	PD4
16	PD5
17	PD6
18	PD7
19	VCC
20	VCC

20 Pin connector SV2 is connected as follows

1	GND
2	GND
3	PC6
4	PC7
5	PE2
6	PE6
7	PF0
8	PF1
9	PF4
10	PF5
11	PF6
12	PF7
13	PF1
14	NC
15	PF5
16	NC
17	PF7
18	AREF
19	VCC
20	VCC

led1 is connected to VCC
led2 is connected to PF6
led3 is connected to PF7
led4 is connected to PE2

programming

This section describes how you get your program into the processor.

In general what you need to know is that the processor will boot into the code you programmed into it on powerup. Once you're done developing your program, that's the way you'll use it: Powerup, run.

If there is no program loaded or if you press the reset button the chip comes up in "firmware upload mode". This is done by a bootloader. You should take care not to overwrite or erase the bootloader, because there is no way to put the bootloader back once it is gone.

Linux

Get the dfu-programmer for atmel chips package. (link?)

On sufficiently recent Ubunu distributions that is as simple as:

 sudo apt-get  install dfu-programmer

I recommend creating a script called "dfu":

#!/bin/sh
if [ -z "$CHIP" ]  ; then 
  chip=at90usb162
else
  chip=$CHIP
fi

hex=$1
sudo dfu-programmer $chip erase
sudo dfu-programmer $chip flash --suppress-bootloader-mem $hex
sudo dfu-programmer $chip start

TODO: figure out how to get rid of the "sudo" commands here...

Now downloading and starting a program is as simple as pressing the reset button and then:

dfu <yourbinary>.hex

TODO: When I'm developing, I'm likely to modify the code, and when I want to program the chip I hit the "reset" button on the board. Then the computer will see my chip re-enumerate as the Atmel DFU chip. A simple script could watchout for that and invoke dfu <mycurrentbinary>.hex the moment the chip has enumerated. Once that's running downloading and starting the latest code becomes as simple as hitting the reset button.

Apparently the FLIP program is now available for Linux too. See below.

windows

Get the "flip" program from Atmel. http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3886

writing programs

The chip is an ATmega32U4. http://www.atmel.com/dyn/resources/prod_documents/doc7766.pdf

You can program the processor as if it is a normal AVR processor without USB. Just like an arduino. Or you can program it to have USB support. For this the LUFA package is very useful. http://www.fourwalledcubicle.com/LUFA.php

Depending on what you want you can start from these examples:

DONE: Find out if we can jump to the bootloader from our code so that we can issue a "go get yourself updated" command over the USB (yes, but the documentation says nothing about what address to jump to). This comes in handy if the reset button is difficult to reach because the device is built-in somewhere. http://www.atmel.com/dyn/resources/prod_documents/doc7618.pdf

future hardware enhancements

allow external reset by providing a header parallel to the onboard switch.
Make an ICSP connector.
Allow the board to work as ICSP programmer through the ICSP connector.

future software enhancements

program the LUFA bootloader.
Program an even smaller bootloader. (512 bytes should be possible, CF teensy/halfkay).

Usbbigmultio

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