Removed majority of the project. What remains is the Optiboot loader, which has been modified to work with
a multi node RS485 network. Uses a sync word to identify each node and requires a modified avrdude to
send the appropriate sync word.
Size of the bootloader reserved space has been increased from 512 bytes to 1024 bytes. Actual memory
usage is 618 bytes, so it might be possible with some pruning to get it back into 512 bytes.
To build optiboot.hex
$ cd software/Optiboot
$ make all
pre-built hex file available at software/Optiboot/pre_built_binaries/
In addition to the programming file, you will also need to program the atmega328pb eeprom with the nodeId.
You can use eepromGen to generate the eeprom contents.
So far I have been unable to get Arduino IDE or avrdude to program the boot loader or the eeprom contents
I have been using Microchip Studio and the Atmel ICE programming hardware connected to the Atmega328pb ISP port.
Unfortunately Microchip Studio only runs under Windows, and is total overkill for just programming the bootloader
and eeprom contents.
avrdude_rs485
There is a python helper script which performs the power cycle and runs avrdude.
[pod_prog](to be completed)
The process for loading new user code is:
- Power cycle the ATMega
- You should see the LED blink fast.
- You now have 8s to program the new code.
- Run pod_prog or avrdude directly, to program the new file.
- Immediately that the programming is complete, the ATmega should run the new code.
Note that there is always an 8s delay for booting user code. This is because Optiboot is configured to wait 8s for new programming activity before it boots user code.