现象
CAN滤波器不正常工作；F4的双路CAN不正常工作。
原因
CAN滤波器设置为32位时，需要向左移动固定位作为滤波，这是STM32底层的规则，HAL库没有屏蔽；
STM32F407的双路CAN，CAN1作为CAN0的从机，需要设置更多的内容，用同一个队列，但是滤波器起始不同。
F1:
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CAN_FilterTypeDef sFilterConfig;
HAL_StatusTypeDef HAL_Status;
sFilterConfig.FilterBank = 0;
sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;
sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;
sFilterConfig.FilterIdHigh = (app->app_io->address + (app->device_type << 8)) << CAN_TI0R_EXID_Pos;
sFilterConfig.FilterIdLow = 0;
sFilterConfig.FilterMaskIdHigh = 0x1FFF << CAN_TI0R_EXID_Pos;
sFilterConfig.FilterMaskIdLow = 0;
sFilterConfig.FilterFIFOAssignment = CAN_FILTER_FIFO0;
sFilterConfig.FilterActivation = ENABLE;
sFilterConfig.SlaveStartFilterBank = 0;
if (hcan.State == HAL_CAN_STATE_LISTENING) HAL_Status = HAL_CAN_Stop(&hcan);
HAL_Status = HAL_CAN_ConfigFilter(&hcan, &sFilterConfig);
HAL_Status = HAL_CAN_Start(&hcan);
HAL_Status = HAL_CAN_ActivateNotification(&hcan, CAN_IT_RX_FIFO0_MSG_PENDING);
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| HAL_CAN_AddTxMessage(&hcan, &TxMessage, data, (uint32_t*)&mailbox);
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F4:
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CAN_FilterTypeDef sFilterConfig;
HAL_StatusTypeDef HAL_Status;
sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;
sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;
sFilterConfig.FilterIdHigh = 0;
sFilterConfig.FilterIdLow = 0;
sFilterConfig.FilterMaskIdHigh = 0;
sFilterConfig.FilterMaskIdLow = 0;
if (hcan == &hcan1) {
sFilterConfig.FilterBank = 0;
}
else {
sFilterConfig.FilterBank = 14;
}
sFilterConfig.FilterFIFOAssignment = CAN_FILTER_FIFO0;
sFilterConfig.SlaveStartFilterBank = 14;
sFilterConfig.FilterActivation = ENABLE;
if (hcan->State == HAL_CAN_STATE_LISTENING) HAL_Status = HAL_CAN_Stop(hcan);
HAL_Status = HAL_CAN_ConfigFilter(hcan, &sFilterConfig);
HAL_Status = HAL_CAN_Start(hcan);
HAL_Status = HAL_CAN_ActivateNotification(hcan, CAN_IT_RX_FIFO0_MSG_PENDING);
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| HAL_CAN_AddTxMessage(&hcan, &TxMessage, data, (uint32_t*)&mailbox);
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其它注意点
需要在STM32CUBEMX中打开的中断只有：
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| F1:
CAN RX1 interrupts
F4:
CAN RX0 interrupts
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需要打开：
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| Automatic Bus-off Management
Automatic Wake-Up mode
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以防止CAN死掉；
波特率计算方法是：
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| (Time Quanta in Bit Segment 1) + (Time Quanta in Bit Segment 2) + 1 = 9 bit
9Bit * Time Quantum = 9 * 444.444ns = 4000ns
1/4000ns = 250kHz
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CAN通信的波特率必须完全匹配，硬线上可能会出现负电压。
2019.9.23:
STM32CubeMX中有一项配置，自动重传：配置的期望和代码生成的结果正好是相反的，一定要注意。
