TI中文支持网Part Number:TMS570LC4357
How to change DLC when sending,如何发送可变字节长度的报文
I modified the DLC value in the cantransmit function, but it still failed. 我在canTransmit函数中修改DLC的值但还是不行
有没有参考的流程，手册我已经看了很多次了还是不太明白。
Green Deng：
你好，问题已经收到，我需要向其他工程师咨询一下之后再回复你，还请耐心等待。
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NA GAO：
谢谢
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NA GAO：
我也想知道如何读取接收到报文的DLC值
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Green Deng：
可以在将数据从 IFx 寄存器传输到 DCAN 消息 RAM 或邮箱之前更新 DLC。 HAL 代码没有更新 DLC 的 API，但可以编写自己的 API。 例如：
void canUpdateDLC(canBASE_t *node, uint32 messageBox, uint8 msgBoxDLC) {/** - Wait until IF2 is ready for use */while ((node->IF2STAT & 0x80U) ==0x80U){} /* Wait */node->IF2CMD = 0x90U;node->IF2MCTL &= ~(uint32)(0xFU);node->IF2MCTL |= (uint32)(msgBoxDLC & 0xFU);node->IF2NO = (uint8) messageBox;/** - Wait until data are copied into IF2 */while ((node->IF2STAT & 0x80U) ==0x80U){} /* Wait */}消息对象的DLC必须定义为与其他节点具有相同标识符的相应对象中的值相同。
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NA GAO：
//可以把这个程序添加在Transmit函数里面吗？
uint32 canTransmit(canBASE_t *node, uint32 messageBox, const uint8 * data,uint8 msgBoxDLC){ uint32 i; uint32 success = 0U; uint32 regIndex = (messageBox – 1U) >> 5U; uint32 bitIndex = 1U << ((messageBox – 1U) & 0x1FU);
/* USER CODE BEGIN (7) */ //添加在这里
/** – Wait until IF2 is ready for use */ while ((node->IF2STAT & 0x80U) ==0x80U) { } /* Wait */
node->IF2CMD = 0x90U;
node->IF2MCTL &= ~(uint32)(0xFU);
node->IF2MCTL |= (uint32)(msgBoxDLC & 0xFU);
node->IF2NO = (uint8) messageBox;
/** – Wait until data are copied into IF2 */ while ((node->IF2STAT & 0x80U) ==0x80U) { } /* Wait */
/* 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 */ /*SAFETYMCUSW 28 D MR:NA <APPROVED> "Potentially infinite loop found – Hardware Status check for execution sequence" */
/** – Copy TX data into IF1 */ for (i = 0U; i < msgBoxDLC; i++) //这里循环条件改成DLC {#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" */ 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" */ 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;
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;}
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NA GAO：
接收到的报文怎么读取DLC
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Green Deng：
收到，我会尽快帮你反馈。
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NA GAO：
使用canUpdateID函数更新ID后，发送的数据帧变成远程帧了，我不知道原因
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Green Deng：
这是新问题？新问题的话还请麻烦新开一个帖子，都放一起会乱
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NA GAO：
谢谢
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Green Deng：
客气了，之前的问题应该会在明天回复你。
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Green Deng：
1、是的，可以将新 ID、DLC 添加到传输 API。
NA GAO 说：/** – Copy TX data into IF1 */ for (i = 0U; i < msgBoxDLC; i++) //这里循环条件改成DLC
这里不必将 8 更改为 msgBoxDLC。 无论 DLC 有多小，八字节数据都会从 IFx 数据寄存器（A 和 B）传输到消息 RAM。
2、DLC 是消息控制寄存器的一部分。 您需要设置 CMD 寄存器的 CONTROL 位和 CMD 寄存器的 CLEAR W/R 位，以便将 DLC 从 Message RAM 传输到 Fx 寄存器：
canGetData(0 API include this portion:
/** – Configure IF2 for* – Message direction – Read* – Data Read* – Clears NewDat bit in the message object.*/node->IF2CMD = 0x17U;/** – Copy data into IF2 *//*SAFETYMCUSW 93 S MR: 6.1,6.2,10.1,10.2,10.3,10.4 <APPROVED> "LDRA Tool issue" */node->IF2NO = (uint8) messageBox;
/** – Wait until data are copied into IF2 *//*SAFETYMCUSW 28 D MR:NA <APPROVED> "Potentially infinite loop found – Hardware Status check for execution sequence" */while ((node->IF2STAT & 0x80U) ==0x80U){} /* Wait */
/** – Get number of received bytes */size = node->IF2MCTL & 0xFU;if(size > 0x8U){size = 0x8U;}/** – Copy RX data into destination buffer */
