I just got a USB AVR programmer for programming a 328 on my MAC. I am interested in the 1284 for a future project. However, I notice in the schematic that the same programmer is built into the board(?) on the 1284. Since programming on a MAC involves updating firmware to the USB AVR programmer, I was wondering, is it possible to bypass the built-in programmer thereby avoiding having to update firmware a second time on a different device?
The Orangutan-SVP’s auxiliary processor is the same model as the processor on the Pololu USB AVR Programmer, but pretty much everything else about them is different. They have different pin assignments and firmware, and you should not attempt to load the firmware of one onto another.
It is easy to bypass the built-in programmer on the SVP. Just connect your standalone programmer to the SVP’s 6-pin ISP connector and everything should work fine. The SVP’s auxiliary processor monitors the AVR’s reset line to detect when you are using an external programmer.
There is a particular setting in avrdude.conf that may cause problems. If you have trouble, please see the “Programming in Linux or Windows using AVRDUDE” section of the Orangutan SVP User’s Guide:
Unfortunately, the SVP’s auxiliary processor uses a type of USB interface that is not supported on Mac OS yet (a composite device with 3 virtual COM ports). This means you won’t be able to use a the SVP’s built-in programmer, the USB-to-TTL serial port, or the direct USB communications port over SPI provided by the auxiliary processor. You will still be able to use all the features of the auxiliary processor that don’t depend on USB though, including quadrature encoder counting, reading the trim pot, reading the battery voltage, or using the A/B/C/D lines as analog inputs.