Usbbigmultio

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Revision as of 14:47, 21 September 2011 by Tom (talk | contribs) (Created page with '= 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 P…')

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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.

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.

pinout

20 Pin connector SV1 is connected as follows

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

20 Pin connector SV2 is connected as follows

1GND
2GND
3PC6
4PC7
5PE2
6PE6
7PF0
8PF1
9PF4
10PF5
11PF6
12PF7
13PF1
14NC
15PF5
16NC
17PF7
18AREF
19VCC
20VCC
  • led1 is connected to VCC
  • led2 is connected to PF6
  • led3 is connected to PF7
  • led4 is connected to PE2


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).