- Moved code for periph_conf of all ATmega based boards to boards/common/atmega
- Added possibility to override config from individual board:
- Named file `periph_conf_atmega_common.h` and let this be included from
`board/$BOARD/include/periph_conf.h` to allow modifications
- Guarded individual periph configs by `#ifndef $PERIPH_NUMOF` ... `#endif`
- correct number of timers for atmega328p from 2 to 1
- correct number of timer channels for atmega328p from 3 to 2
- adapt atmega periph timer implementation accordingly
This adds a LED_PANIC macro which defines which LED,
or combination of LEDs should notify a panic error.
This is currently used to signal BADISR_vect errors.
Fixes#5745
For AVR based boards, three defines must be defined AVR_CONTEXT_SWAP_INIT,
AVR_CONTEXT_SWAP_INTERRUPT_VECT, and AVR_CONTEXT_SWAP_TRIGGER.
These defines are used to trigger a software interrupt used for context
switching.
When AVR_CONTEXT_SWAP_INTERRUPT_VECT is handled, the scheduler is run
and a context swap will happen if necessary, with the resulting thread
starting following the reti instruction. This results in threads running
at normal priority instead of at interrupt priority.
Atmega devices do provide a pure software interrupt. The method used
here for waspmote-pro and arduino-mega2560 is to use pin change
interrupts, set the pin to act as an output, and toggle the value to
simulate a software interrupt. The main limitation here is that a
physical pin is now occupied and must be defined for each board
supported by RIOT. On the plus side, it provides an easy method for
detecting context swaps with an oscilloscope.
