Libcanard on chibios

skyyuzhang · October 17, 2018, 7:24am

if I want to using libcanard on chibios with stm32f103 how do I initialize canbus hardware

pavel.kirienko · October 17, 2018, 3:52pm

UAVCAN/libcanard/blob/9d2e2904d25c0df10dc78a17ba915cdb13d54292/drivers/stm32/canard_stm32.h#L111-L132


/**
* Initializes the CAN controller at the specified bit rate.
* The mode can be either normal, silent, or auto-abort on error;
* in silent mode the controller will be only listening, not affecting the state of the bus;
* in the auto abort mode the controller will cancel the pending transmissions if a bus error is encountered.
* The auto abort mode is needed for dynamic node ID allocation procedure; please refer to the UAVCAN specification
* for more information about this topic.
*
* This function can be invoked any number of times; every invocation re-initializes everything from scratch.
*
* WARNING: The clock of the CAN module must be enabled before this function is invoked!
*          If CAN2 is used, CAN1 must be also enabled!
*
* WARNING: The driver is not thread-safe!
*          It does not use IRQ or critical sections though, so it is safe to invoke its API functions from the
*          IRQ context from the application.
*
* @retval      0               Success
* @retval      negative        Error
*/

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skyyuzhang · October 18, 2018, 11:38am

should I do some specific driver on chibios ? I mean when using libcanard on no rtos we should do hwInit(); which include RCC_APB1PeriphClockCmd() and GPIO_PinAFConfig. so on chibios what should we do like RCC_APB1PeriphClockCmd() or nothing to do

pavel.kirienko · October 18, 2018, 1:05pm

With ChibiOS you only need to enable the clock signal to the CAN controller, that’s it. Here are relevant examples:

github.com

Zubax/zubax_gnss/blob/81d55f2c83cbc95e71cfc86b2c86173ebbaec480/bootloader/src/board/board.cpp#L262-L274


/*
 * Enabling the CAN controllers, then configuring GPIO functions for CAN_TX.
 * Order matters, otherwise the CAN_TX pins will twitch, disturbing the CAN bus.
 * This is why we can't perform this initialization using ChibiOS GPIO configuration.
 *
 * NOTE: Check this - the problem may only appear when CAN pin remapping is used,
 *       because ChibiOS initializes AFIO after GPIO.
 */
RCC->APB1ENR |= RCC_APB1ENR_CAN1EN;
palSetPadMode(GPIOB, 9, PAL_MODE_STM32_ALTERNATE_PUSHPULL);
// Enabling CAN2 too, in order to avoid bus disruptions
RCC->APB1ENR |= RCC_APB1ENR_CAN2EN;
palSetPadMode(GPIOB, 13, PAL_MODE_STM32_ALTERNATE_PUSHPULL);

github.com

Zubax/zubax_gnss/blob/master/bootloader/src/board/can.hpp

/*
 * Copyright (C) 2017  Zubax Robotics  <info@zubax.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Author: Pavel Kirienko <pavel.kirienko@zubax.com>
 */

#pragma once

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