Port to Attiny85 chip using Software UART

[Daniel]

Hi, I was planning to use this stack on small Attiny85 module I had already produced the pcb and assembly for a home made protocol and it have only one power transistor output but I was looking to converting these module to bacnet but I am not able to figure if it would be possible to adapt the stack to use a software uart and where to start. Does anybody already tried to do it yet?
Attiny85 Datasheet
Atmel Application note to make half duplex software Uart

Thanks a lot !

[Steve Karg]

There is a port to Atmega8 (see ports/atmega8) of an MS/TP slave node that compiles under IAR EWAVR:
7 469 bytes of CODE memory (+ 18 range fill )
831 bytes of DATA memory (+ 14 absolute )

You would need to port the rs485.c code and any other hardware differences in the ATtiny85. You would also need to reduce the RAM usage down to 512 bytes.

You could also contact Polarsoft. They recently completed an Assembler BACnet Stack to ATmega644p that could be also ported to ATtiny85.