Electronic – Re-programming an AVR from another MCU over SPI

avrispspi

Many AVRs have the capability to be ISP'd – or in system programmed over SPI. I have a project where the entire device can get firmware updates, and I'd like to also update the firmware on it's front panel from the main micro. Since the front panel is conveniently connected through SPI, I've had the idea of just re-programming it from my main MCU over SPI.

That's the ISP method, which would be quite easy and would not require me to write a boot loader. If I can't do the ISP, then of course I will be needing a bootloader.

So basically – can another MCU re-program the ATMEGA644 over the SPI bus?

Best Answer

Yes, very easily. In this scenario, RESET works as the active-low slave-select. The programming algorithm is very well documented in every AVR datasheet (look under Memory programming, Serial Downloading).

Note however that some AVR chips have their ICSP SPIs on different pins than their regular SPIs (for example, atmega128 shares the ICSP SPI with one of its USARTs).

Related Solutions

Electronic – Arduino Bootloader Details

void (*app_start)(void) = 0x0000;

This isn't a NULL pointer. This really is the address of the start of application code, which the bootloader jumps to. The linker arranges for your application code to start at address 0. See table 26-6 in the ATMEGA168 datasheet.

The bootloader code starts higher up in flash. Exactly where depends on the bootloader fuses.

Electronic – Arduino Diecimila (ATMEGA168) + JTAG ICE MKII Hell..Did I Fry the Chip

I believe I may have found a two part solution for my particular problem. I currently own an Arduino Diecimila (which has the ATMEGA168 with the problem) and also a new Arduino Nano 3.0. I went ahead and flashed the Arduino Nano with the ArduinoISP firmware. I then picked up 3 28 Pin ATMEGA328P DIP chips for $5.00 each at the local electronics store.

I used the ArduinoISP to flash one of the virgin chips with the Arduino Firmware using the above link with a crystal. I plan to now flash one of the other ATMEGA328Ps with the High Voltage Programmer firmware. This chip along with a bit of wiring on a breadboard should allow me to reset all of the fuses on the original ATMEGA168. Once that is done, I will be able to use the Arduino Nano to reprogram the chip.

Since the ATMEGA328Ps only cost $5 each, my end goal is to setup one 328 as an Arduino ISP programmer, setup the 168 as a HV Programmer, keep one 328 chip in my current Arduino Diecimila (upgrade!!), and I'll have one left over for whatever. I can then either switch chips on the Diecimila or build out a real board for the ISP and HV Programmer boards.

I still have not tested the JTAG ICE MKII yet with a logic/oscilloscope. Not sure if it is the root of the problem or not. I will address this issue after I build the HV Programmer.

I will report back on the success/failure of the HV Programmer. I just need to go get a few more 1K resistors to pull it off. Anyone ever tried the HV Programmer? Any other suggestions? If nothing else, hope this helps someone.

Best Answer

Related Solutions

Electronic – Arduino Bootloader Details

Electronic – Arduino Diecimila (ATMEGA168) + JTAG ICE MKII Hell..Did I Fry the Chip

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