DW1000测距例程问题笔记
说明
在做DW1000的驱动移植测试时遇到了很多问题，这里记录下
SPI问题
SPI问题的驱动移植是比较常见的难点，Decawave的示例驱动只有基于STM32平台的，对于大部分人在使用其他平台时都要重新实现SPI的驱动
常见的问题在于SPI的读写不通，这个需要通过对芯片寄存器进行读写测试并配合逻辑分析仪来对SPI时序进行分析来确认。
uint8 dataA[20] = {0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55};
uint8 dataB[20];
dwt_writetodevice(0x21, 0, 20, &dataA[0]);
dwt_readfromdevice(0x21, 0, 20, &dataB[0]);
可以参考上述代码对0x21寄存器(DW1000中的数据缓存寄存器)进行读写回读来确认基本的SPI通信是否正常
另外，需要确保高速SPI和低速SPI切换接口正常，芯片默认的SPI速率为3Mhz以下，需要进行初始化后才能支持到20Mhz，对于某些应用场景，高速SPI是必须的
/* @fn port_set_dw_ic_spi_slowrate
* @brief set 2MHz
* */
void port_set_dw_ic_spi_slowrate(void);
/* @fn port_set_dw_ic_spi_fastrate
* @brief set 16MHz
* */
void port_set_dw_ic_spi_fastrate(void);
测距例程的时序
一般来讲，SPI通了就可以正常的跑通Simple TX/RX例程。但是对于测距例程DW Ranging可能还是会跑不通，这个往往是由于时序问题导致的异常。
常见的是rsp端在第一次接收到数据后，准备进行延迟发送时出现发送失败
/* Set send time for response. See NOTE 9 below. */
resp_tx_time = (poll_rx_ts + (POLL_RX_TO_RESP_TX_DLY_UUS * UUS_TO_DWT_TIME)) >> 8;
dwt_setdelayedtrxtime(resp_tx_time);
/* Set expected delay and timeout for final message reception. See NOTE 4 and 5 below. */
dwt_setrxaftertxdelay(RESP_TX_TO_FINAL_RX_DLY_UUS);
dwt_setrxtimeout(FINAL_RX_TIMEOUT_UUS);
/* Write and send the response message. See NOTE 10 below.*/
tx_resp_msg[ALL_MSG_SN_IDX] = frame_seq_nb;
dwt_writetxdata(sizeof(tx_resp_msg), tx_resp_msg, 0); /* Zero offset in TX buffer. */
dwt_writetxfctrl(sizeof(tx_resp_msg), 0, 1); /* Zero offset in TX buffer, ranging. */
ret = dwt_starttx(DWT_START_TX_DELAYED | DWT_RESPONSE_EXPECTED);
/* If dwt_starttx() returns an error, abandon this ranging exchange and proceed to the next one. See NOTE 11 below. */
if (ret == DWT_ERROR)
{
continue;
}
即最后的调用starttx函数会失败
nt dwt_starttx(uint8 mode)
{
int retval = DWT_SUCCESS ;
uint8 temp = 0x00;
uint16 checkTxOK = 0 ;
if(mode & DWT_RESPONSE_EXPECTED)
{
temp = (uint8)SYS_CTRL_WAIT4RESP ; // Set wait4response bit
pdw1000local->wait4resp = 1;
}
if (mode & DWT_START_TX_DELAYED)
{
// Both SYS_CTRL_TXSTRT and SYS_CTRL_TXDLYS to correctly enable TX
temp |= (uint8)(SYS_CTRL_TXDLYS | SYS_CTRL_TXSTRT) ;
dwt_write8bitoffsetreg(SYS_CTRL_ID, SYS_CTRL_OFFSET, temp);
checkTxOK = dwt_read16bitoffsetreg(SYS_STATUS_ID, 3); // Read at offset 3 to get the upper 2 bytes out of 5
if ((checkTxOK & SYS_STATUS_TXERR) == 0) // Transmit Delayed Send set over Half a Period away or Power Up error (there is enough time to send but not to power up individual blocks).
{
retval = DWT_SUCCESS ; // All okay
}
else
{
// If HPDWARN or TXPUTE are set this indicates that the TXDLYS was set too late for the specified DX_TIME.
// remedial action is to cancel delayed send and report error
dwt_write8bitoffsetreg(SYS_CTRL_ID, SYS_CTRL_OFFSET, (uint8)SYS_CTRL_TRXOFF);
retval = DWT_ERROR ; // Failed !
}
}
else
{
temp |= (uint8)SYS_CTRL_TXSTRT ;
dwt_write8bitoffsetreg(SYS_CTRL_ID, SYS_CTRL_OFFSET, temp);
}
return retval;
} // end dwt_starttx()
如果查看函数执行过程发现是checkTxOK标志失败，并且把这个标志位读出来发现是0x08的话，那就说明是出现了HPDWARN错误
即发送时间太晚了，延迟时间结束了都还没发，因此需要增加延迟时间，让发送能来得及
/* UWB microsecond (uus) to device time unit (dtu, around 15.65 ps) conversion factor.
* 1 uus = 512 / 499.2 ?s and 1 ?s = 499.2 * 128 dtu. */
#define UUS_TO_DWT_TIME 65536
/* Delay between frames, in UWB microseconds. See NOTE 4 below. */
/* This is the delay from Frame RX timestamp to TX reply timestamp used for calculating/setting the DW1000's delayed TX function. This includes the
* frame length of approximately 2.46 ms with above configuration. */
#define POLL_RX_TO_RESP_TX_DLY_UUS 4600 //default:2600
/* This is the delay from the end of the frame transmission to the enable of the receiver, as programmed for the DW1000's wait for response feature. */
#define RESP_TX_TO_FINAL_RX_DLY_UUS 500 //default:500
/* Receive final timeout. See NOTE 5 below. */
#define FINAL_RX_TIMEOUT_UUS 5300 //default:3300
/* Preamble timeout, in multiple of PAC size. See NOTE 6 below. */
#define PRE_TIMEOUT 800 //default:8
即类似与DW Raging测距例程中的上述参数
对于直接用例程的参数还跑不通的，要注意下SPI速率是否设置的和例程一致，例程中会有将SPI速率进行切换到高速或者低速的操作，要是没有实现高速SPI切换的接口也会导致时序错误
其他建议
Decawave对于常见的问题有总结出排查参考手册，可以在官网上下载APS022_Debugging-DW1000-Based-Products-and-Systems_v1.3这份文档来参考
