TI中文支持网Part Number:TMS570LS3137
在使用canTransmit函数时，每次发送的数据长度不固定，1~8，如何将长度信息更新的DLC并发送
Ben Qin：
参考下这个帖子：
e2echina.ti.com/…/tms570lc4357-how-to-change-dlc-when-sending
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x x：
我已经设置 node->IF1CMD = 0x97U;，而且已经更新node->IF1MCTL &= 0xFFFFFF00;node->IF1MCTL |= dlc;从变量监视穿孔也看到DLC被改变，但是CAN接收到，长度依旧为8，
uint32 canTransmitWithDLC(canBASE_t *node, uint32 messageBox, const uint8 * data,const uint8 dlc) {uint32 i;uint32 success= 0U;uint32 regIndex = (messageBox - 1U) >> 5U;uint32 bitIndex = 1U << ((messageBox - 1U) & 0x1FU);/* USER CODE BEGIN (7) */ /* USER CODE END *//** - Check for pending message:*- pending message, return 0*- no pending message, start new transmission*/if ((node->TXRQx[regIndex] & bitIndex) != 0U){success = 0U;}else{/** - Wait until IF1 is ready for use *//*SAFETYMCUSW 28 D MR:NA <APPROVED> "Potentially infinite loop found - Hardware Status check for execution sequence" */while ((node->IF1STAT & 0x80U) ==0x80U){} /* Wait *//** - Configure IF1 for*- Message direction - Write*- Data Update*- Start Transmission*/node->IF1CMD = 0x97U;/** - Copy TX data into IF1 */for (i = 0U; i < 8U; i++){ #if ((__little_endian__ == 1) || (__LITTLE_ENDIAN__ == 1))/*SAFETYMCUSW 45 D MR:21.1 <APPROVED> "Valid non NULL input parameters are only allowed in this driver" */node->IF1DATx[i] = *data;/*SAFETYMCUSW 45 D MR:21.1 <APPROVED> "Valid non NULL input parameters are only allowed in this driver" *//*SAFETYMCUSW 567 S MR:17.1,17.4 <APPROVED> "Pointer increment needed" */data++; #else/*SAFETYMCUSW 45 D MR:21.1 <APPROVED> "Valid non NULL input parameters are only allowed in this driver" */node->IF1DATx[s_canByteOrder[i]] = *data;/*SAFETYMCUSW 45 D MR:21.1 <APPROVED> "Valid non NULL input parameters are only allowed in this driver" *//*SAFETYMCUSW 567 S MR:17.1,17.4 <APPROVED> "Pointer increment needed" */data++; #endif}/** - Copy TX data into message box *//*SAFETYMCUSW 93 S MR: 6.1,6.2,10.1,10.2,10.3,10.4 <APPROVED> "LDRA Tool issue" */node->IF1NO = (uint8) messageBox;node->IF1MCTL &= 0xFFFFFF00;node->IF1MCTL |= dlc;success = 1U;}/**@note The function canInit has to be called before this function can be used.\n*The user is responsible to initialize the message box.*//* USER CODE BEGIN (8) */ /* USER CODE END */return success; }
，图中为监视状态，看起来是没有生效
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x x：
更正一下，调整代码位置，则发送正确
/*如果代码这样写，发送的首帧长度依然为8；*/ node->IF1NO = (uint8) messageBox;node->IF1MCTL &= 0xFFFFFF00; node->IF1MCTL |= dlc;/*代码这样写，发送数据的DLC则更新为输入参数dlc；*/ node->IF1MCTL &= 0xFFFFFF00; node->IF1MCTL |= dlc;node->IF1NO = (uint8) messageBox;
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Ben Qin：
好的，感谢分享，问题解决就好
