[chbot] ATMEL ICSP in-circuit programming , prop plug programming redux

[Charles Manning]

There are two ways to program the AVR (discounting the debug interfaces for 
now):

* UART style as is done with Arduino. This needs a "bootloader" preprogrammed 
onto the AVR. This is just RS232-like and  will work with an unmodified 
prop-plug so  long as you get the pin outs right. It will also work with a 
regular RS232 serial port translation chip like a MAX232.

* ISP mode. This works with a raw micro and does not need a boot loader. 
However this needs an extra control pin...

UART style (Arduino) programming only need ground, RX, TX and a reset. ie 3 
signal pins

ISP mode requires ground, reset, MOSI, MISO, Clock. ie 4 signal pins.

ISP mode programming is easily achieved with the avrdude software which 
supports numerous different hardware configuration including:
* parallel port: 
* serial port:
* ftdi chip: (could probably modify a prop plug to do this).
* USBTinyISP etc.
and Google will find you more.

I have used parallel programmers in the past and found them sometimes 
unreliable.

I used simplified version of the  ponyser 
(http://core.st/projects/Serial_programmer/index.html) for a bit. That's fast 
enough on directly wired serial port but is far too slow for proper use on a 
USB to serial adapter.

I now use a USBTinyISP V2 (we now have two in the family). This is a USB 
programmer that runs the USB protocol on an AVR chip and is very fast. I 
bought the kit from http://www.ladyada.net/make/usbtinyisp/ for around $US30 
including shipping but it is easy enough to make your own for around $20NZ. 
All the schematics and firmware is published and free to use.

There are two versions of the USBTinyISP:
* Version 1: http://www.ladyada.net/images/usbtinyisp/usbtinyisp.png Handles a 
reduced voltage range, but simpler. You don't need all those connectors at 
the top of the schematic.
* Version2: http://www.ladyada.net/images/usbtinyisp/usbtinyisp2sch.png has an 
extra buffer chip to handle a wider voltage range.

Hope that helps...

Charles