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你好:
我在C2000Ware4.0版本的支持包中使用了有关MCAN的例程,其中接收部分的例程尚且可以正常使用。但是唯独ex9,无法使用,其中的BRS需要置0,才可以做CANFD发送,但是这样就无法使用CANFD加速模式。所以需要工作人员帮忙定位一下问题的原因,和解决办法。
C2000的版本::C2000Ware_4_02_00_00_setup.exe
CCS版本:CCS12.2.0.00009
硬件平台:就是官方的LaunchPad 280039 (例程中对应的IO已修改,满足开发板的状态)
但是唯独ex9,无法使用,其中的BRS需要置0,
Could you give more information regarding this? (what is the data bit rate? What values are fed to the MCAN_DBTP register?)
The examples have been tested and verified regularly so there should not be any issues to run them out-of-the-box.
Given the fact, that the example only seems to be working with Bit Rate Switch disabled, there seems to be an issue with the data bit rate configuration. Please check the same in your setup.
你好,我已确认过数据域波特率设置并未修改,就是例程中的1Mbps。
此外我想确认一下,按照采样点计算公式(1+TimeSeg1)/ (1+TimerSeg1+TimerSeg2)计算的结果,TI这边的采样点才55%?但是按照相关CAN标准,波特率500kbps时,采样点推荐87.5%。所以想确认TI的采样点是如何计算的。
你好,我已确认过数据域波特率设置并未修改,就是例程中的1Mbps。
As I mentioned before, at the default settings, communication has been tested, so this will need further looking into.
Is it possible for the customer to check with an oscilloscope (preferably one that can decode CAN frames) the readings on the transmit pin, if the frame is as expected?
但是按照相关CAN标准,波特率500kbps时,采样点推荐87.5%。
I will look into it and get back to you on that.
所以想确认TI的采样点是如何计算的。
All timing related parameters are calculated by a spreadsheet that has been provided in the C2000ware package: C2000Ware_X_XX_00_00\device_support\f28003x\docs\MCAN_BitTimingCalculator
抱歉,我这边没有可以对CAN信息解码的示波器,所以用例程跑了一下,用普通上位机记录。如下是MCAN_ex9_transmit例程发送时的数据波形。这时候程序在“while(HWREG(MCANA_DRIVER_BASE + MCAN_TXBTO) == 0x00000000)”处等待。
如果在初始化中将BRS位置零,那么可以正常发送,且发送时波形如下:
程序在“while(HWREG(MCANA_DRIVER_BASE + MCAN_TXBTO) == 0x00000000)”处等待等待时,MCAN寄存器的值,如下:
之前询问的“按照相关CAN标准,波特率500kbps时,采样点推荐87.5%”,这个问题能解答一下吗?
I tried this on a F28388D. I tried both Ex3 and Ex9 examples. BRS works correctly as intended. Please see the captured waveforms below. MSGID_2us.png shows a bit from the MSGID with a nominal bit-time of 2 us. Data-bit_1us.png shows a bit from the data portion with a data bit-time of 1 us. So, there is no problem with BRS in the MCAN module. It could be that the bit-timing configuration is incorrect. I will try with a F20039 Launchpad tomorrow. Is the customer using the C2000ware example "as is" without any modification? Are they running the code in Launchpad or in their own board? If it is their own board, is the terminator resistor installed correctly?
抱歉。
我不赞同你们认为问题已经解决。
我这边依然无法使用ex9例程进行传输报文,如果需要修改例程或者开发板状态请明说,或者贵司工作人员,未修改例程和板子状态,请提供一下,测试平台和设备,以及测试过程。我希望我这边能根据你们的测试状态复现一下。这个问题已经快两个月未解决了,还是希望能得到一个有效的答复。
谢谢