Quote:
Originally Posted by SiriusHardware
I actually quite like your idea of a standalone board into which you place an AVR chip which has been programmed in the usual way in an UNO.
Pros:
-No longer has the size / space limitation imposed by trying to keep it inside the outline of an Arduino shield. You can make it physically bigger.
-Power applied to the programmer PCB applies power to everything simultaneously, power removed from the board removes power from everything.
Cons: Need to own an Arduino UNO just to programme the chip, although the chip can be put straight back in the Arduino and re-used again one you've done your PROM programming job. Could maybe put a programming connector on the programmer PCB to allow the micro to be programmed via AVRDUDE or some such, to avoid the need to own an Arduino.
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To be honest, if I get it working it would be relatively trivial (a days work or so) to add the ATMEGA to the schematic and lay out a new board. There would be no software changes required on the ATMEGA or the PC software unless I moved pins around. You could use a cheap USB-serial module soldered to the board to actually program the device using the boot loader, and to communicate with the programmer, and the USB power would be isolated. Although DIP ATMEGA328's pre-programmed with the boot loader are stupid prices at the moment they will come down in price to the cost of an UNO clone or less at some time so that would be an option. To add in the usual SPI programming port to allow an AVRISP, "Arduino as ISP" or USBISP to program a blank chip would involve moving around some of the I/O pins but that in itself wouldn't be a huge issue since the 10 address + CE pins are completely isolated if there is no PROM in the socket so there's room to get isolated pins on PORTB for programming.
This is work I would probably do, as I am more interested in there being a usable open source design out there to program these chips than the (few) highly expensive obsolete commercial designs out there, and realistically I am not in a position to make and sell them myself. Just need to get on with it!