This works by adjusting the bit positions for the Timer1 Compare Match A interrupt. In file Source/portable/GCC/ATMega323/port.c on line 52 you will find: -——-> snip #define portCOMPARE_MATCH_A_INTERRUPT_ENABLE    ( ( unsigned portCHAR ) 0x10 ) -——-< snap Replace this with: -——-> snip #define portCOMPARE_MATCH_A_INTERRUPT_ENABLE    ( ( unsigned portCHAR ) (1<<OCIE1A) ) -——-< snap This works for ATmega8515 and should for ATmega323 and others. At least with AVR-GCC, as include/avr/io.h defines the neccessary bit positions. I think using these is a better idea than hard coding them, but I don’t know if IAR will work with this as well. If it does I can provide a version where the other constants are generalized this way too. Thanks for making the FreeRTOS-stuff public! Philipp

Thanks for your ideas. I will update the AVR demo soon so the downloaded demo is targeted at one of the newer devices.  The aim would be to make it portable accross all devices with no mods required.