前言

官网: CAN with Flexible Data Rate (CAN FD) (xilinx.com)

特征:

• 支持8Mb/s的CANFD
• 多达 3 个数据位发送器延迟补偿(TDC, transmitter delay compensation)
• 32-deep TX FIFO, 2 * 64-deep RX FIFO, 32 ID Filter
• 接收支持 顺序(Sequential)模式 和 邮箱(Mailbox)模式
• Bus-Off 恢复模式: 自动恢复 或 用户干预的自动恢复

参考:

• How to configure CAN/CANFD clocks and identify the CAN nodes (xilinx.com)
• canfd 默认文档和示例路径: C:\Xilinx\Vitis\2023.2\data\embeddedsw\XilinxProcessorIPLib\drivers\canfd_v2_8

本文仅作学习交流使用.

测试用的硬件连接

硬件:

• FPGA: xc7a35tfgg484-2
• 时钟: 50MHz, 有源, 单端, 3V3, 引脚Y18
• 复位: 低电平复位, 3V3, 引脚F20
• UART: TX G16, RX G15
• CANFD: TX F16, RX E17

Vivado 配置

如图:

时钟:

• clk_out1, 160MHz, can_clk_x2, 也是其它组件的时钟
• clk_out2, 80MHz, can_clk, 是CAN和CANFD配置的主时钟
• 低电平复位

调试串口:

• 9600 or 115200 bps

时钟的配置截图

CANFD的配置, 收发FIFO Depth都是32, 接收使用顺序模式, 不用FIFO1

可适当减少RX FIFO-0 Depth以减少RAM消耗. 含MicroBlaze 64K, 一路CANFD, 没有使用任何外部RAM的消耗如下(xc7a35tfgg484-2):

Vitis MicroBlaze CANFD 代码

初始化:

• 查找并初始化已有CANFD配置
• 进入配置模式, 配置位速率, 采样点, TDC, 滤波器, 关闭BRS
• 设置收发错误事件回调, 使能中断
• 进入正常模式
• 注意在C文件中编译, 不然Cpp中 XSetupInterruptSystem 会报错 error: invalid conversion from 'void (*)(void*)' to 'void*' [-fpermissive]

参考代码如下:

int bsp_canfd_init(XCanFd *InstancePtr, uint32_t BaseAddress, uint32_t BaudRate,float SamplePoint, uint32_t FastBaudRate,float FastSamplePoint) {XCanFd_Config *ConfigPtr = XCanFd_LookupConfig(BaseAddress);if (ConfigPtr == NULL) {bsp_canfd_debug_printf("Error: XCanFd_LookupConfig returned NULL\n");return -1;} else {bsp_canfd_debug_printf("XCanFd_Config:\n");bsp_canfd_debug_printf("  BaseAddress: 0x%08X\n", ConfigPtr->BaseAddress);bsp_canfd_debug_printf("  Rx_Mode: %s\n",ConfigPtr->Rx_Mode ? "Mailbox" : "Sequential");bsp_canfd_debug_printf("  NumofRxMbBuf: %d\n", ConfigPtr->NumofRxMbBuf);bsp_canfd_debug_printf("  NumofTxBuf: %d\n", ConfigPtr->NumofTxBuf);bsp_canfd_debug_printf("  IntrId: %d\n", ConfigPtr->IntrId);bsp_canfd_debug_printf("  IntrParent: 0x%08X\n", ConfigPtr->IntrParent);}int Status =XCanFd_CfgInitialize(InstancePtr, ConfigPtr, ConfigPtr->BaseAddress);if (Status != XST_SUCCESS) {bsp_canfd_debug_printf("Error: XCanFd_CfgInitialize returned %d\n", Status);return -2;} else {bsp_canfd_debug_printf("XCanFd_CfgInitialize: Success\n");}// config modeXCanFd_EnterMode(InstancePtr, XCANFD_MODE_CONFIG);while (XCanFd_GetMode(InstancePtr) != XCANFD_MODE_CONFIG);bsp_canfd_debug_printf("XCanFd_EnterMode: XCANFD_MODE_CONFIG\n");// 80MHz / (3 + 1) = 20MHz, 20MHz / (1 + (30 + 1) + (7 + 1)) = 500KHz// XCanFd_SetBitTiming(InstancePtr, 8, 7, 30);XCanFd_SetBaudRatePrescaler(InstancePtr, 0x3);u16 total_tq = 20000000 / BaudRate;u16 tseg1 = (u16)(SamplePoint * total_tq) - 2;u8 tseg2 = (u8)(total_tq - tseg1 - 3);u8 sjw = tseg2 + 1;XCanFd_SetBitTiming(InstancePtr, sjw, tseg2, tseg1);// 80MHz, 80 / (1 + (30 + 1) + (7 + 1)) = 2MHz// XCanFd_SetFBitTiming(InstancePtr, 8, 7, 30);XCanFd_SetFBaudRatePrescaler(InstancePtr, 0x0);u16 ftotal_tq = 80000000 / FastBaudRate;u8 ftseg1 = (u8)(FastSamplePoint * ftotal_tq) - 2;u8 ftseg2 = (u8)(ftotal_tq - ftseg1 - 3);u8 fsjw = ftseg2 + 1;XCanFd_SetFBitTiming(InstancePtr, fsjw, ftseg2, ftseg1);// TDC, 0~31// XCanFd_Set_Tranceiver_Delay_Compensation(InstancePtr, 0x3);XCanFd_SetBitRateSwitch_DisableNominal(InstancePtr);bsp_canfd_debug_printf("XCanFd: %d@0.%d, %d@0.%d\n", BaudRate,(int)(SamplePoint * 1000), FastBaudRate,(int)(FastSamplePoint * 1000));if (XCANFD_GET_RX_MODE(InstancePtr) == 0) {bsp_canfd_debug_printf("RX_MODE Sequential Filter: XCANFD_AFR_UAF_ALL_MASK\n");XCanFd_AcceptFilterDisable(InstancePtr, XCANFD_AFR_UAF_ALL_MASK);XCanFd_AcceptFilterEnable(InstancePtr, XCANFD_AFR_UAF_ALL_MASK);} else {bsp_canfd_debug_printf("RX_MODE Mailbox Filter: Need to be implemented\n");}XCanFd_SetHandler(InstancePtr, XCANFD_HANDLER_SEND, (void *)SendHandler,(void *)InstancePtr);XCanFd_SetHandler(InstancePtr, XCANFD_HANDLER_RECV, (void *)RecvHandler,(void *)InstancePtr);XCanFd_SetHandler(InstancePtr, XCANFD_HANDLER_ERROR, (void *)ErrorHandler,(void *)InstancePtr);XCanFd_SetHandler(InstancePtr, XCANFD_HANDLER_EVENT, (void *)EventHandler,(void *)InstancePtr);Status =XSetupInterruptSystem(InstancePtr, &XCanFd_IntrHandler, ConfigPtr->IntrId,ConfigPtr->IntrParent, XINTERRUPT_DEFAULT_PRIORITY);if (Status != XST_SUCCESS) {bsp_canfd_debug_printf("Error: XSetupInterruptSystem returned %d\n",Status);return 1;} else {bsp_canfd_debug_printf("XSetupInterruptSystem: Success\n");}XCanFd_InterruptEnable(InstancePtr, XCANFD_IXR_ALL);XCanFd_EnterMode(InstancePtr, XCANFD_MODE_NORMAL);while (XCanFd_GetMode(InstancePtr) != XCANFD_MODE_NORMAL);bsp_canfd_debug_printf("XCanFd_EnterMode: XCANFD_MODE_NORMAL\n");return 0;
}

发送套用Linux SocketCAN接口, 毕竟这个用的人多, 易于理解. 因为发送FIFO深度为32, 所以, 正常情况下连发32帧无需插入延时, 也无需自己处理发送队列, 这已经够大部分情况使用了.

int bsp_canfd_send(XCanFd *InstancePtr, struct canfd_frame *frame) {bool is_extended = frame->can_id & CAN_EFF_FLAG ? true : false;bool is_remote = frame->can_id & CAN_RTR_FLAG ? true : false;bool is_fd = frame->flags & CANFD_FDF ? true : false;bool is_brs = frame->flags & CANFD_BRS ? true : false;bool is_esi = frame->flags & CANFD_ESI ? true : false;u32 TxFrame[CANFD_MTU];TxFrame[0] = XCanFd_CreateIdValue(CAN_SFF_MASK & (is_extended ? ((frame->can_id & CAN_EFF_MASK) >> 18): frame->can_id),is_extended ? 1 : (u32)is_remote, (u32)is_extended,(u32)is_extended ? (frame->can_id & 0x3FFFF) : 0,is_extended ? (u32)is_remote : 0);if ((!is_fd) && (!is_brs)) {TxFrame[1] = XCanFd_CreateDlcValue(frame->len);} else {if (is_brs) {TxFrame[1] =XCanFd_Create_CanFD_Dlc_BrsValue(XCanFd_GetLen2Dlc(frame->len));} else {TxFrame[1] = XCanFd_Create_CanFD_DlcValue(XCanFd_GetLen2Dlc(frame->len));}}u8 *FramePtr = (u8 *)(&TxFrame[2]);for (int i = 0; i < frame->len; i++) {FramePtr[i] = frame->data[i];}u32 TxBufferNumber;int status = XCanFd_Send(InstancePtr, TxFrame, &TxBufferNumber);if (status == XST_FIFO_NO_ROOM) {bsp_canfd_debug_printf("Error: XCanFd_Send returned XST_FIFO_NO_ROOM\n");return -1;}if (status != XST_SUCCESS) {bsp_canfd_debug_printf("Error: XCanFd_Send returned %d\n", status);return -2;}return 0;
}

接收的示例, 类似 candump:

• 标准帧是%03X打印, 扩展帧是%08X打印.
• 远程帧打R, 数据帧打D
• CANFD打F且长度为[%02d], Classic CAN打-且数据长度为[%d]
• 开启了BRS打B, 否则打-
• ESI 暂不关心
• 当然这里打印接收只是用于测试, 实际不要在中断中阻塞打印

static void RecvHandler(void *CallBackRef) {XCanFd *CanPtr = (XCanFd *)CallBackRef;int Status;u32 RxFrame[CANFD_MTU];/* Check for the design 1 - MailBox 0 - Sequential */if (XCANFD_GET_RX_MODE(CanPtr) == 1) {Status = XCanFd_Recv_Mailbox(CanPtr, RxFrame);} else {Status = XCanFd_Recv_Sequential(CanPtr, RxFrame);}u32 id1 = (RxFrame[0] >> (u32)XCANFD_IDR_ID1_SHIFT) & (u32)0x7FF;u32 is_extended = (RxFrame[0] >> (u32)XCANFD_IDR_IDE_SHIFT) & (u32)0x1;u32 id2 = (RxFrame[0] >> (u32)XCANFD_IDR_ID2_SHIFT) & (u32)0x3FFFF;u32 is_remote = is_extended? (RxFrame[0] & 0x01): ((RxFrame[0] >> (u32)XCANFD_IDR_SRR_SHIFT) & (u32)0x1);/* Get the Dlc inthe form of bytes */u32 len = XCanFd_GetDlc2len(RxFrame[1] & XCANFD_DLCR_DLC_MASK, EDL_CANFD);if (Status != XST_SUCCESS) {bsp_canfd_debug_printf("Error: XCanFd_Recv returned %d\n", Status);return;}u32 is_brs = RxFrame[1] & XCANFD_DLCR_BRS_MASK ? 1 : 0;u32 is_fdf = RxFrame[1] & XCANFD_DLCR_EDL_MASK ? 1 : 0;// bsp_canfd_debug_printf("%08X ", RxFrame[0]);u8 *FramePtr = (u8 *)(&RxFrame[2]);if (is_extended) {bsp_canfd_debug_printf("%08X ", id1 << 18 | id2);} else {bsp_canfd_debug_printf("%03X ", id1);}if (is_remote) {bsp_canfd_debug_printf("R [%d]", len);} else {bsp_canfd_debug_printf("D ");if (is_fdf) {bsp_canfd_debug_printf("F ");} else {bsp_canfd_debug_printf("- ");}if (is_brs) {bsp_canfd_debug_printf("B ");} else {bsp_canfd_debug_printf("- ");}if ((!is_fdf) && (!is_brs)) {bsp_canfd_debug_printf("[%d] ", len);} else {bsp_canfd_debug_printf("[%02d] ", len);}for (int i = 0; i < len; i++) {bsp_canfd_debug_printf("%02X ", FramePtr[i]);}}bsp_canfd_debug_printf("\n");
}

测试代码

如下:

• 位速率 500K@80%, 4M@80%, 如果出现收发不正常, 可能需要微调初始化中的TDC, 检查CAN收发器以及终端电阻
• 对数据帧远程帧, CAN或CANFD或CANFD BRS都做了测试
• 连续发送32帧

int main() {xil_printf("============================================\n");XCanFd CanFd0;int Status =bsp_canfd_init(&CanFd0, XPAR_CANFD_0_BASEADDR, 500000, 0.8, 4000000, 0.8);if (Status != 0) {xil_printf("Error: bsp_canfd_init returned %d\n", Status);return -1;}for (int i = 0; i < 4; i++) {struct canfd_frame frame = {.can_id = 0x123,.len = 8,.flags = 0,.__res0 = 0,.__res1 = 0,.data = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x13,0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D,0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30, 0x31,0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B,0x3C, 0x3D, 0x3E, 0x3F},};// std canframe.can_id = 0x123;frame.len = 8;frame.flags = 0;int Status = bsp_canfd_send(&CanFd0, &frame);// std can remoteframe.can_id = 0x124 | CAN_RTR_FLAG;frame.len = 8;frame.flags = 0;Status |= bsp_canfd_send(&CanFd0, &frame);// std can fdframe.can_id = 0x125;frame.len = 64;frame.flags = CANFD_FDF;Status |= bsp_canfd_send(&CanFd0, &frame);// std can fd brsframe.can_id = 0x126;frame.len = 64;frame.flags = CANFD_FDF | CANFD_BRS;Status |= bsp_canfd_send(&CanFd0, &frame);// ext canframe.can_id = 0x12345678 | CAN_EFF_FLAG;frame.len = 8;frame.flags = 0;Status |= bsp_canfd_send(&CanFd0, &frame);// ext can remoteframe.can_id = 0x12345679 | CAN_EFF_FLAG | CAN_RTR_FLAG;frame.len = 8;frame.flags = 0;Status |= bsp_canfd_send(&CanFd0, &frame);// ext can fdframe.can_id = 0x1234567A | CAN_EFF_FLAG;frame.len = 64;frame.flags = CANFD_FDF;Status |= bsp_canfd_send(&CanFd0, &frame);// ext can fd brsframe.can_id = 0x1234567B | CAN_EFF_FLAG;frame.len = 64;frame.flags = CANFD_FDF | CANFD_BRS;Status |= bsp_canfd_send(&CanFd0, &frame);if (Status != 0) {xil_printf("Error: bsp_canfd_send %d returned %d\n", i, Status);return -1;}}while (1) {}return 0;
}

测试截图

设置:

MCU连续发出的32帧报文:

逻辑分析仪上可以看出来两帧之间卡着标准的3 ITM来的

出现BRS时的情况, 左边500K, 右边4M

CAN分析仪向FPGA发送测试:

Github Link

domain_controller_orin_x2_tc397/axi_canfd_microblaze at main · weifengdq/domain_controller_orin_x2_tc397 (github.com)