STM32F765芯片上电后以1秒的周期，CAN1和CNA2定时发送一帧数据，CAN1和CNA2在发送十帧左右数据后停止发送，断电查看发现是邮箱0、1、2状态不对。用的hal库，在HAL_CAN_Transmit函数下

if(((hcan->Instance->TSR&CAN_TSR_TME0) == CAN_TSR_TME0) || ((hcan->Instance->TSR&CAN_TSR_TME1) == CAN_TSR_TME1) || ((hcan->Instance->TSR&CAN_TSR_TME2) == CAN_TSR_TME2)) {

...................

}else { / Change CAN state / hcan->State = HAL_CAN_STATE_ERROR;

/ Return function status / return HAL_ERROR; }

程序运行进入了else下hcan->State = HAL_CAN_STATE_ERROR，请教下是什么原因导致的？