用STM32F103CBT6测试CAN例程始终发送失败如何解决

单片机用的是STM32F103CBT6
RTT版本是lts-v3.1.4
将BSP里的CAN驱动.c和.h加入到工程
开启宏定义#define BSP_USING_CAN #define BSP_USING_CAN1
CubeMX生成的HAL_CAN_MspInit(CAN_HandleTypeDef* hcan)函数加入到board.c
板子通过CAN盒连接到电脑，用ＣＡＮｔｅｓｔ接收
修改ＣＡＮ例程为周期发送，后附代码

问题：控制台通过ｌｉｓｔ＿ｄｅｖｉｃｅ可以看到ＣＡＮ１已经注册，运行例程始终发送失败，
\ | /

RT - Thread Operating System
/ | \ 3.1.4 build Jul 31 2020
2006 - 2019 Copyright by rt-thread team
[D/main] Hello RT-Thread!
msh >list_device
device type ref count
can1 CAN Device 0
uart2 Character Device 2
pin Miscellaneous Device 0
msh >can_sample
can dev write data failed!
can dev write data failed!
can dev write data failed!
can dev write data failed!
can dev write data failed!
can dev write data failed!
can dev write data failed!

include
include “rtdevice.h”
define CAN_DEV_NAME “can1” / CAN 设备名称 /
static rt_device_t can_dev; / CAN 设备句柄 /

int can_sample(int argc, char *argv[])
{
struct rt_can_msg msg = {0};
rt_err_t res;
rt_size_t size;

can_dev = rt_device_find(CAN_DEV_NAME);
if (!can_dev)
{
rt_kprintf("find %s failed!\n", CAN_DEV_NAME);
return RT_ERROR;
}
/* 以中断接收及发送方式打开CAN设备 */
res = rt_device_open(can_dev, RT_DEVICE_FLAG_INT_TX | RT_DEVICE_FLAG_INT_RX);
RT_ASSERT(res == RT_EOK);
rt_device_control(can_dev, RT_CAN_CMD_SET_MODE, (void *)RT_CAN_MODE_NORMAL);
rt_device_control(can_dev, RT_CAN_CMD_SET_BAUD,(void )CAN250kBaud);
msg.id = 0x78; / ID为0x78 /
msg.ide = RT_CAN_STDID; / 标准格式 /
msg.rtr = RT_CAN_DTR; / 数据帧 /
msg.len = 8; / 数据长度为8 /
/ 待发送的8字节数据 /
msg.data[0] = 0x00;
msg.data[1] = 0x11;
msg.data[2] = 0x22;
msg.data[3] = 0x33;
msg.data[4] = 0x44;
msg.data[5] = 0x55;
msg.data[6] = 0x66;
msg.data[7] = 0x77;
/ 发送一帧CAN数据 */
while(1){
size = rt_device_write(can_dev, 0, &msg, sizeof(msg));
if (size == 0)
{
rt_kprintf("can dev write data failed!\n");
}
rt_thread_mdelay(1000);
}
return res;
}
/ 导出到 msh 命令列表中 /
MSH_CMD_EXPORT(can_sample, can device sample);