【经验分享】STM32F7xx —— CAN通信

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STMCU小助手发布时间：2021-12-11 12:00

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文章简介:	STM32F7xx —— CAN通信

一、CAN基础
差分信号：显性电平对应逻辑0，CAN_H和CAN_L差为2.5V；隐形电平对应逻辑1，CAN_H和CAN_L差为0V。

CAN总线的开始和结束都有一个120Ω的终端电阻。

数据帧：标准帧11位，扩展帧29位。

其他的一些理论知识就不再赘述了，可以参考维基百科对于CAN的描述。

STM32F7xx的bxCAN主要特点：支持CAN2.0A和CAN2.0B，波特率高达1Mbps，支持时间触发，具有3个发送邮箱，2个接收邮箱，可变的过滤器组等。

二、几个重要的CAN函数

HAL_StatusTypeDef HAL_CAN_Init(CAN_HandleTypeDef* hcan); // CAN初始化
HAL_StatusTypeDef HAL_CAN_Transmit(CAN_HandleTypeDef *hcan, uint32_t Timeout); // CAN发送
HAL_StatusTypeDef HAL_CAN_Receive(CAN_HandleTypeDef *hcan, uint8_t FIFONumber, uint32_t Timeout); // CAN接收

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三、几个重要的结构

// CAN操作句柄包含CAN基地址（CAN1/CAN2/CAN3）初始化结构发送接收结构体其余三个是过程变量
typedef struct
{
CAN_TypeDef *Instance; /*!< Register base address */
CAN_InitTypeDef Init; /*!< CAN required parameters */
CanTxMsgTypeDef* pTxMsg; /*!< Pointer to transmit structure */
CanRxMsgTypeDef* pRxMsg; /*!< Pointer to reception structure */
__IO HAL_CAN_StateTypeDef State; /*!< CAN communication state */
HAL_LockTypeDef Lock; /*!< CAN locking object */
__IO uint32_t ErrorCode; /*!< CAN Error code */
}CAN_HandleTypeDef;

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// CAN配置结构体
// 前5个参数来设置 CAN_BTR —— 波特率
// 后6个参数用来设置 CAN_MCR —— 通信相关的控制位
typedef struct
{
uint32_t Prescaler; /*!< Specifies the length of a time quantum.
This parameter must be a number between Min_Data = 1 and Max_Data = 1024 */
uint32_t Mode; /*!< Specifies the CAN operating mode.
This parameter can be a value of @ref CAN_operating_mode */
uint32_t SJW; /*!< Specifies the maximum number of time quanta
the CAN hardware is allowed to lengthen or
shorten a bit to perform resynchronization.
This parameter can be a value of @ref CAN_synchronisation_jump_width */
uint32_t BS1; /*!< Specifies the number of time quanta in Bit Segment 1.
This parameter can be a value of @ref CAN_time_quantum_in_bit_segment_1 */
uint32_t BS2; /*!< Specifies the number of time quanta in Bit Segment 2.
This parameter can be a value of @ref CAN_time_quantum_in_bit_segment_2 */
uint32_t TTCM; /*!< Enable or disable the time triggered communication mode.
This parameter can be set to ENABLE or DISABLE. */
uint32_t ABOM; /*!< Enable or disable the automatic bus-off management.
This parameter can be set to ENABLE or DISABLE */
uint32_t AWUM; /*!< Enable or disable the automatic wake-up mode.
This parameter can be set to ENABLE or DISABLE */
uint32_t NART; /*!< Enable or disable the non-automatic retransmission mode.
This parameter can be set to ENABLE or DISABLE */
uint32_t RFLM; /*!< Enable or disable the receive FIFO Locked mode.
This parameter can be set to ENABLE or DISABLE */
uint32_t TXFP; /*!< Enable or disable the transmit FIFO priority.
This parameter can be set to ENABLE or DISABLE */
}CAN_InitTypeDef;

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// 过滤器设置
typedef struct
{
uint32_t FilterIdHigh; /*!< Specifies the filter identification number (MSBs for a 32-bit
configuration, first one for a 16-bit configuration).
This parameter must be a number between Min_Data = 0x0000 and Max_Data = 0xFFFF */
uint32_t FilterIdLow; /*!< Specifies the filter identification number (LSBs for a 32-bit
configuration, second one for a 16-bit configuration).
This parameter must be a number between Min_Data = 0x0000 and Max_Data = 0xFFFF */
uint32_t FilterMaskIdHigh; /*!< Specifies the filter mask number or identification number,
according to the mode (MSBs for a 32-bit configuration,
first one for a 16-bit configuration).
This parameter must be a number between Min_Data = 0x0000 and Max_Data = 0xFFFF */
uint32_t FilterMaskIdLow; /*!< Specifies the filter mask number or identification number,
according to the mode (LSBs for a 32-bit configuration,
second one for a 16-bit configuration).
This parameter must be a number between Min_Data = 0x0000 and Max_Data = 0xFFFF */
uint32_t FilterFIFOAssignment; /*!< Specifies the FIFO (0 or 1) which will be assigned to the filter.
This parameter can be a value of @ref CAN_filter_FIFO */
uint32_t FilterNumber; /*!< Specifies the filter which will be initialized.
This parameter must be a number between Min_Data = 0 and Max_Data = 27 */
uint32_t FilterMode; /*!< Specifies the filter mode to be initialized.
This parameter can be a value of @ref CAN_filter_mode */
uint32_t FilterScale; /*!< Specifies the filter scale.
This parameter can be a value of @ref CAN_filter_scale */
uint32_t FilterActivation; /*!< Enable or disable the filter.
This parameter can be set to ENABLE or DISABLE. */
uint32_t BankNumber; /*!< Select the start slave bank filter.
This parameter must be a number between Min_Data = 0 and Max_Data = 28 */
}CAN_FilterConfTypeDef;

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// 模式我们使用普通模式
#define CAN_MODE_NORMAL ((uint32_t)0x00000000U) /*!< Normal mode */
#define CAN_MODE_LOOPBACK ((uint32_t)CAN_BTR_LBKM) /*!< Loopback mode */
#define CAN_MODE_SILENT ((uint32_t)CAN_BTR_SILM) /*!< Silent mode */
#define CAN_MODE_SILENT_LOOPBACK ((uint32_t)(CAN_BTR_LBKM | CAN_BTR_SILM)) /*!< Loopback combined with silent mode */

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// 标准帧扩展帧
#define CAN_ID_STD ((uint32_t)0x00000000U) /*!< Standard Id */
#define CAN_ID_EXT ((uint32_t)0x00000004U) /*!< Extended Id */

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// 数据帧远程帧
#define CAN_RTR_DATA ((uint32_t)0x00000000U) /*!< Data frame */
#define CAN_RTR_REMOTE ((uint32_t)0x00000002U) /*!< Remote frame */

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// CAN中断使能
__HAL_CAN_ENABLE_IT(__HANDLE__, __INTERRUPT__)

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// 接收中断
#define CAN_IT_FMP0 ((uint32_t)CAN_IER_FMPIE0) /*!< FIFO 0 message pending interrupt */
#define CAN_IT_FF0 ((uint32_t)CAN_IER_FFIE0) /*!< FIFO 0 full interrupt */
#define CAN_IT_FOV0 ((uint32_t)CAN_IER_FOVIE0) /*!< FIFO 0 overrun interrupt */
#define CAN_IT_FMP1 ((uint32_t)CAN_IER_FMPIE1) /*!< FIFO 1 message pending interrupt */
#define CAN_IT_FF1 ((uint32_t)CAN_IER_FFIE1) /*!< FIFO 1 full interrupt */
#define CAN_IT_FOV1 ((uint32_t)CAN_IER_FOVIE1) /*!< FIFO 1 overrun interrupt */

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四、接口设计
与串口类似，使用中断接收。先封装单路CAN需要的几个小接口，再顶一个列表，最后使用统一的接口扫描这个列表。

typedef enum
{
CAN_CHANNEL_NONE,
CAN_CHANNEL_1,
CAN_CHANNEL_2,
CAN_CHANNEL_NUM
} can_channel_t;
#define CAN1_CHANNEL CAN1
#define CAN1_PREEMPT_PRIO CAN1_RX_PRIORITY
#define CAN1_RX_IRQ CAN1_RX0_IRQn
#define CAN1_RX_IRQ_FUNC CAN1_RX0_IRQHandler
#define CAN1_CLK_ENABLE() __HAL_RCC_CAN1_CLK_ENABLE()
#define CAN1_TX_PORT GPIOA
#define CAN1_TX_PIN GPIO_PIN_12
#define CAN1_TX_AF GPIO_AF9_CAN1
#define CAN1_TX_CONFIG() GPIOConfigExt(CAN1_TX_PORT, CAN1_TX_PIN, GPIO_MODE_AF_PP, GPIO_PULLUP, CAN1_TX_AF)
#define CAN1_RX_PORT GPIOA
#define CAN1_RX_PIN GPIO_PIN_11
#define CAN1_RX_AF GPIO_AF9_CAN1
#define CAN1_RX_CONFIG() GPIOConfigExt(CAN1_RX_PORT, CAN1_RX_PIN, GPIO_MODE_AF_PP, GPIO_PULLUP, CAN1_RX_AF)
#define CAN2_CHANNEL CAN2
#define CAN2_PREEMPT_PRIO CAN2_RX_PRIORITY
#define CAN2_RX_IRQ CAN2_RX0_IRQn
#define CAN2_RX_IRQ_FUNC CAN2_RX0_IRQHandler
#define CAN2_CLK_ENABLE() __HAL_RCC_CAN2_CLK_ENABLE()
#define CAN2_TX_PORT GPIOB
#define CAN2_TX_PIN GPIO_PIN_6
#define CAN2_TX_AF GPIO_AF9_CAN2
#define CAN2_TX_CONFIG() GPIOConfigExt(CAN2_TX_PORT, CAN2_TX_PIN, GPIO_MODE_AF_PP, GPIO_PULLUP, CAN2_TX_AF)
#define CAN2_RX_PORT GPIOB
#define CAN2_RX_PIN GPIO_PIN_5
#define CAN2_RX_AF GPIO_AF9_CAN2
#define CAN2_RX_CONFIG() GPIOConfigExt(CAN2_RX_PORT, CAN2_RX_PIN, GPIO_MODE_AF_PP, GPIO_PULLUP, CAN2_RX_AF)

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// 抽象出一个CAN设备结构体
typedef struct
{
CAN_HandleTypeDef handle; // CAN操作句柄
CanTxMsgTypeDef tx; // CAN发送
CanRxMsgTypeDef rx; // CAN接收
can_queue_t recv; // 接收队列
} can_dev_t;

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// 将每路CAN封装成几个小函数
static can_dev_t can1_dev, can2_dev;
static void can1_var_init(void)
{
can1_dev.recv = can1_queue_recv;
CanQueueInit(&can1_dev.recv);
}
static void can1_gpio_init(void)
{
CAN1_TX_CONFIG();
CAN1_RX_CONFIG();
}
// 波特率 = Fpclk1 / ((ts1+ts2+3) * brp) Fpclk1 = 54M
static void can1_mode_init(void)
{
CAN1_CLK_ENABLE();
can1_dev.handle.Instance = CAN1_CHANNEL;
can1_dev.handle.pTxMsg = &can1_dev.tx;
can1_dev.handle.pRxMsg = &can1_dev.rx;
can1_dev.handle.Init.Prescaler = 6;
can1_dev.handle.Init.Mode = CAN_MODE_NORMAL;
can1_dev.handle.Init.SJW = CAN_SJW_1TQ; // 重新同步跳跃宽度(Tsjw)为tsjw+1个时间单位 CAN_SJW_1TQ~CAN_SJW_4TQ
can1_dev.handle.Init.BS1 = CAN_BS1_11TQ;// tbs1范围CAN_BS1_1TQ~CAN_BS1_16TQ
can1_dev.handle.Init.BS2 = CAN_BS2_6TQ; // tbs2范围CAN_BS2_1TQ~CAN_BS2_8TQ
can1_dev.handle.Init.TTCM = DISABLE; // 非时间触发通信模式
can1_dev.handle.Init.ABOM = ENABLE; // 软件自动离线管理
can1_dev.handle.Init.AWUM = DISABLE; // 睡眠模式通过软件唤醒(清除CAN->MCR的SLEEP位)
can1_dev.handle.Init.NART = ENABLE; // 禁止报文自动传送
can1_dev.handle.Init.RFLM = DISABLE; // 报文不锁定,新的覆盖旧的
can1_dev.handle.Init.TXFP = DISABLE; // 优先级由报文标识符决定
HAL_CAN_Init(&can1_dev.handle);
}
static void can1_filter_init(void)
{
CAN_FilterConfTypeDef filter;
filter.FilterNumber = 0; // 过滤器0
filter.FilterMode = CAN_FILTERMODE_IDMASK;
filter.FilterScale = CAN_FILTERSCALE_32BIT;
filter.FilterIdHigh = 0;
filter.FilterIdLow = 0;
filter.FilterMaskIdHigh = 0;
filter.FilterMaskIdLow = 0;
filter.FilterFIFOAssignment = CAN_FILTER_FIFO0; // 过滤器0关联到FIFO0
filter.FilterActivation = ENABLE; //激活滤波器0
//filter.BankNumber=14;
HAL_CAN_ConfigFilter(&can1_dev.handle, &filter);
}
static void can1_nvic_init(void)
{
__HAL_CAN_ENABLE_IT(&can1_dev.handle, CAN_IT_FMP0); //FIFO0消息挂号中断允许.
HAL_NVIC_SetPriority(CAN1_RX_IRQ, CAN1_RX_PRIORITY, 0);
HAL_NVIC_EnableIRQ(CAN1_RX_IRQ);
}
static void can2_var_init(void)
{
can2_dev.recv = can2_queue_recv;
CanQueueInit(&can2_dev.recv);
}
static void can2_gpio_init(void)
{
CAN2_TX_CONFIG();
CAN2_RX_CONFIG();
}
// 波特率 = Fpclk1 / ((ts1+ts2+3) * brp) Fpclk1 = 54M
static void can2_mode_init(void)
{
CAN2_CLK_ENABLE();
can2_dev.handle.Instance = CAN2_CHANNEL;
can2_dev.handle.Init.Prescaler = 6;
can2_dev.handle.Init.Mode = CAN_MODE_LOOPBACK;
can2_dev.handle.Init.SJW = CAN_SJW_1TQ; // 重新同步跳跃宽度(Tsjw)为tsjw+1个时间单位 CAN_SJW_1TQ~CAN_SJW_4TQ
can2_dev.handle.Init.BS1 = CAN_BS1_11TQ;// tbs1范围CAN_BS1_1TQ~CAN_BS1_16TQ
can2_dev.handle.Init.BS2 = CAN_BS2_6TQ; // tbs2范围CAN_BS2_1TQ~CAN_BS2_8TQ
can2_dev.handle.Init.TTCM = DISABLE; // 非时间触发通信模式
can2_dev.handle.Init.ABOM = ENABLE; // 软件自动离线管理
can2_dev.handle.Init.AWUM = DISABLE; // 睡眠模式通过软件唤醒(清除CAN->MCR的SLEEP位)
can2_dev.handle.Init.NART = ENABLE; // 禁止报文自动传送
can2_dev.handle.Init.RFLM = DISABLE; // 报文不锁定,新的覆盖旧的
can2_dev.handle.Init.TXFP = DISABLE; // 优先级由报文标识符决定
HAL_CAN_Init(&can2_dev.handle);
}
static void can2_filter_init(void)
{
CAN_FilterConfTypeDef CAN_FilterInitStructure;
CAN_FilterInitStructure.FilterNumber = 14;
CAN_FilterInitStructure.FilterMode = CAN_FILTERMODE_IDMASK;
CAN_FilterInitStructure.FilterScale = CAN_FILTERSCALE_32BIT;
CAN_FilterInitStructure.FilterIdHigh = 0;
CAN_FilterInitStructure.FilterIdLow = 0;
CAN_FilterInitStructure.FilterMaskIdHigh = 0;
CAN_FilterInitStructure.FilterMaskIdLow = 0;
CAN_FilterInitStructure.FilterFIFOAssignment = CAN_FILTER_FIFO0; // 过滤器0关联到FIFO0
CAN_FilterInitStructure.FilterActivation = ENABLE; //激活滤波器0
//CAN_FilterInitStructure.BankNumber=14;
HAL_CAN_ConfigFilter(&can2_dev.handle, &CAN_FilterInitStructure);
}
static void can2_nvic_init(void)
{
__HAL_CAN_ENABLE_IT(&can2_dev.handle, CAN_IT_FMP0); //FIFO0消息挂号中断允许1
HAL_NVIC_SetPriority(CAN2_RX_IRQ, CAN2_RX_PRIORITY, 0);
HAL_NVIC_EnableIRQ(CAN2_RX_IRQ);
}

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// 每路CAN都有的几个操作，使用列表包含，然后统一扫描处理
typedef struct
{
uint8_t channel;
can_dev_t *dev;
void (* var_init_cb)(void);
void (* gpio_init_cb)(void);
void (* mode_init_cb)(void);
void (* filter_init_cb)(void);
void (* nvic_init_cb)(void);
} can_config_t;
static const can_config_t can_configs[] =
{
{CAN_CHANNEL_1, &can1_dev, can1_var_init, can1_gpio_init, can1_mode_init, can1_filter_init, can1_nvic_init},
{CAN_CHANNEL_2, &can2_dev, can2_var_init, can2_gpio_init, can2_mode_init, can2_filter_init, can2_nvic_init},
};
static can_dev_t *can_dev_get(uint8_t channel)
{
uint8_t i;
for(i = 0; i < ARRAY_SIZE(can_configs); ++i)
{
if(channel == can_configs.channel)
{
return can_configs.dev;
}
}
return 0;
}
static void can_var_init(uint8_t channel)
{
uint8_t i;
for(i = 0; i < ARRAY_SIZE(can_configs); ++i)
{
if(channel == can_configs.channel)
{
can_configs.var_init_cb();
return;
}
}
}
static void can_gpio_init(uint8_t channel)
{
uint8_t i;
for(i = 0; i < ARRAY_SIZE(can_configs); ++i)
{
if(channel == can_configs.channel)
{
can_configs.gpio_init_cb();
return;
}
}
}
static void can_mode_init(uint8_t channel)
{
uint8_t i;
for(i = 0; i < ARRAY_SIZE(can_configs); ++i)
{
if(channel == can_configs.channel)
{
can_configs.mode_init_cb();
return;
}
}
}
static void can_filter_init(uint8_t channel)
{
uint8_t i;
for(i = 0; i < ARRAY_SIZE(can_configs); ++i)
{
if(channel == can_configs.channel)
{
can_configs.filter_init_cb();
return;
}
}
}
static void can_nvic_init(uint8_t channel)
{
uint8_t i;
for(i = 0; i < ARRAY_SIZE(can_configs); ++i)
{
if(channel == can_configs.channel)
{
can_configs.nvic_init_cb();
return;
}
}
}