N3_sub/modules/libcanard/drivers/avr/README.md

Libcanard Driver for AVR Microcontrollers

This driver is based on the Universal CAN Library for AVR controllers (AT90CAN, MCP2515, SJA1000) by RCA (Roboterclub Aachen e.V.).

Github: https://github.com/dergraaf/avr-can-lib

Important

Only tested for AT90CAN128!

Currently the driver works only with additional buffer from the avr-can-lib (see below) as the internal CAN Buffer (MOb's) are not read fast enough and therefore overflow occur even with hardware filter enabled.

#define CAN_RX_BUFFER_SIZE              16
#define CAN_TX_BUFFER_SIZE              8
#define CAN_FORCE_TX_ORDER              1

How-to

Setup library

Adjust file can_config.h to your needs. In file CMakeLists.txt set your controller and corresponding frequency:

set(MCU   at90can128)
set(F_CPU 16000000)

After finishing configuration:

$ cmake .
$ make

Include the following files in your project:

• avr-can-lib/can.h
• avr-can-lib/libcan.a
• can_config.h

Use

1. Initialize canardAVRInit(CAN_BITRATE) with appropriate bitrate (bits/sec.)
2. Retrieve (allocation of dynamic node ID) or set node ID manually
3. Set CAN hardware filter canardAVRConfigureAcceptanceFilters(NODE_ID) with node ID from above