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Post By：2018-11-27 15:54:00 [只看該作者]
代碼如下：
tr[0].tx_buf = (unsigned long)tx;
tr[0].rx_buf = NULL;
tr[0].len = 2;
tr[0].delay_usecs = 0;
tr[0].speed_hz = Speed;
tr[0].bits_per_word = Bits;
tr[0].cs_change=0; //add to keep cs actived
tr[1].tx_buf = (unsigned long)par;
tr[1].rx_buf = NULL;
tr[1].len = 4;
tr[1].delay_usecs = 0;
// tr[1].speed_hz = 0;
// tr[1].bits_per_word = 0;
tr[1].speed_hz = Speed;
tr[1].bits_per_word = Bits;
tr[1].cs_change=0; //add to keep cs actived
tr[2].tx_buf = (unsigned long)tx2;
tr[2].rx_buf = NULL;
tr[2].len = 2;
tr[2].delay_usecs = 0;
tr[2].speed_hz = Speed;
tr[2].bits_per_word = Bits;
tr[2].cs_change=0; //add to keep cs actived
ret = ioctl(m_fd, SPI_IOC_MESSAGE(3), tr );
我們?cè)贓SM335X上面跑的時(shí)候，硬件的CS一直保持低電平，無(wú)論有沒(méi)有cs_change=0的語(yǔ)句，但在6800上cs在中間一直會(huì)回到高電平，如下圖
