70 lines
2.3 KiB
C
70 lines
2.3 KiB
C
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#include "can.h"
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u8 can_init() {
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// Enable CAN1 peripheral
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RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);
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// Enable AFIORCC_APB2Periph_AFIO | GPIOA
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RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO | RCC_APB2Periph_GPIOA, ENABLE);
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// Set up GPIO on port A
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GPIO_InitTypeDef GPIO_InitStructure;
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GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
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// CAN1_RX - PA11
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GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
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GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
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GPIO_Init(GPIOA, &GPIO_InitStructure);
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// CAN1_TX - PA12
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GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
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GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
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GPIO_Init(GPIOA, &GPIO_InitStructure);
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// Disable filters so we can actually receive things
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CAN_FilterInitTypeDef CAN_FilterInitStruct;
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CAN_FilterInitStruct.CAN_FilterNumber = 0;
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CAN_FilterInitStruct.CAN_FilterMode = CAN_FilterMode_IdMask;
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CAN_FilterInitStruct.CAN_FilterScale = CAN_FilterScale_32bit;
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CAN_FilterInitStruct.CAN_FilterIdHigh = 0x0000;
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CAN_FilterInitStruct.CAN_FilterIdLow = 0x0000;
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CAN_FilterInitStruct.CAN_FilterMaskIdHigh = 0x0000;
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CAN_FilterInitStruct.CAN_FilterMaskIdLow = 0x0000;
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CAN_FilterInitStruct.CAN_FilterFIFOAssignment = CAN_FIFO0;
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CAN_FilterInitStruct.CAN_FilterActivation = ENABLE;
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CAN_FilterInit(&CAN_FilterInitStruct);
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// Init the can controller, set baud rate to 1Mbps
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// Formula for baud:
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// SysClk = 72MHz
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// AHB = 72MHz
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// APB1 = AHB / 2 = 36MHz
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// Bitrate = APB1 / ((BS1 + BS2 + 1) * Prescaler)
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// 1Mbaud = 36MHz / ((14 + 3 + 1) * 2)
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//
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// Other values that work, BS1=5, BS2=3, Div=4
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// For now I use values that are as close to CTRE's candle light code
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CAN_InitTypeDef CAN_InitStructure;
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CAN_StructInit(&CAN_InitStructure);
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CAN_InitStructure.CAN_Prescaler = 4;
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CAN_InitStructure.CAN_SJW = CAN_SJW_1tq;
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CAN_InitStructure.CAN_BS1 = CAN_BS1_5tq;
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CAN_InitStructure.CAN_BS2 = CAN_BS2_3tq;
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return CAN_Init(CAN1, &CAN_InitStructure);
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}
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u8 can_recv(CanRxMsg *RxMessage) {
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u8 got_msg = 0;
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if(CAN_MessagePending(CAN1, CAN_FIFO0)) {
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CAN_Receive(CAN1, CAN_FIFO0, RxMessage);
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got_msg = 1;
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} else if(CAN_MessagePending(CAN1, CAN_FIFO1)) {
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CAN_Receive(CAN1, CAN_FIFO1, RxMessage);
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got_msg = 1;
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}
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return got_msg;
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}
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