From d1563a9cafa83f7b4932e7885d5cb1b52f108375 Mon Sep 17 00:00:00 2001
From: zhyinch <zhyinch@gmail.com>
Date: 星期六, 13 七月 2019 23:02:37 +0800
Subject: [PATCH] 广州200套出货程序，修改通讯时间参数
---
源码/核心板/Src/application/dw_app.c | 253 ++++++++++++++++++++++++++-----------------------
1 files changed, 134 insertions(+), 119 deletions(-)
diff --git "a/\346\272\220\347\240\201/\346\240\270\345\277\203\346\235\277/Src/application/dw_app.c" "b/\346\272\220\347\240\201/\346\240\270\345\277\203\346\235\277/Src/application/dw_app.c"
index ef8d58c..10ddad8 100644
--- "a/\346\272\220\347\240\201/\346\240\270\345\277\203\346\235\277/Src/application/dw_app.c"
+++ "b/\346\272\220\347\240\201/\346\240\270\345\277\203\346\235\277/Src/application/dw_app.c"
@@ -3,12 +3,7 @@
* @file main.c
* @brief Double-sided two-way ranging (DS TWR) initiator example code
*
- * This is a simple code example which acts as the initiator in a DS TWR distance measurement exchange. This application sends a "poll"
- * frame (recording the TX time-stamp of the poll), and then waits for a "response" message expected from the "DS TWR responder" example
- * code (companion to this application). When the response is received its RX time-stamp is recorded and we send a "final" message to
- * complete the exchange. The final message contains all the time-stamps recorded by this application, including the calculated/predicted TX
- * time-stamp for the final message itself. The companion "DS TWR responder" example application works out the time-of-flight over-the-air
- * and, thus, the estimated distance between the two devices.
+ *
*
* @attention
*
@@ -30,7 +25,8 @@
#include "Usart.h"
#include "global_param.h"
#include "filters.h"
-
+#include <stdio.h>
+#include "beep.h"
/*------------------------------------ Marcos ------------------------------------------*/
@@ -50,9 +46,9 @@
#define POLL_TX_TO_RESP_RX_DLY_UUS 150
/* 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 2.66 ms with above configuration. */
-#define RESP_RX_TO_FINAL_TX_DLY_UUS 1500
+#define RESP_RX_TO_FINAL_TX_DLY_UUS 400
/* Receive response timeout. See NOTE 5 below. */
-#define RESP_RX_TIMEOUT_UUS 2700
+#define RESP_RX_TIMEOUT_UUS 600
#define POLL_RX_TO_RESP_TX_DLY_UUS 420
/* 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. */
@@ -63,7 +59,6 @@
#define SPEED_OF_LIGHT 299702547
/* Indexes to access some of the fields in the frames defined above. */
-#define ALL_MSG_SN_IDX 2
#define FINAL_MSG_POLL_TX_TS_IDX 10
#define FINAL_MSG_RESP_RX_TS_IDX 14
#define FINAL_MSG_FINAL_TX_TS_IDX 18
@@ -71,9 +66,12 @@
#define GROUP_ID_IDX 0
#define ANCHOR_ID_IDX 1
-#define TAG_ID_IDX 3
-#define MESSAGE_TYPE_IDX 5
-#define DIST_IDX 6
+#define TAG_ID_IDX 5
+#define MESSAGE_TYPE_IDX 9
+#define DIST_IDX 10
+#define ANC_TYPE_IDX 14
+#define BATTARY_IDX 15
+#define BUTTON_IDX 16
#define POLL 0x01
#define RESPONSE 0x02
@@ -82,7 +80,7 @@
/*------------------------------------ Variables ------------------------------------------*/
/* Default communication configuration. We use here EVK1000's default mode (mode 3). */
static dwt_config_t config = {
- 5, /* Channel number. */
+ 2, /* Channel number. */
DWT_PRF_64M, /* Pulse repetition frequency. */
DWT_PLEN_128, /* Preamble length. */
DWT_PAC8, /* Preamble acquisition chunk size. Used in RX only. */
@@ -95,12 +93,12 @@
};
/* Frames used in the ranging process. See NOTE 2 below. */
-static uint8_t tx_poll_msg[] = {0x00, 0x88, 0, 0xCA, 0xDE, 'W', 'A', 'V', 'E', 0x21, 0, 0};
+static uint8_t tx_poll_msg[19] = {0};
//static uint8_t rx_resp_msg[] = {0x41, 0x88, 0, 0xCA, 0xDE, 'V', 'E', 'W', 'A', 0x10, 0x02, 0, 0, 0, 0};
static uint8_t tx_final_msg[] = {0x41, 0x88, 0, 0xCA, 0xDE, 'W', 'A', 'V', 'E', 0x23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
//static uint8_t rx_poll_msg[] = {0x00, 0x88, 0, 0xCA, 0xDE, 'W', 'A', 'V', 'E', 0x21, 0, 0};
-static uint8_t tx_resp_msg[] = {0x41, 0x88, 0, 0xCA, 0xDE, 'V', 'E', 'W', 'A', 0x10, 0x02, 0, 0, 0, 0};
+static uint8_t tx_resp_msg[16] = {0};
//static uint8_t rx_final_msg[] = {0x41, 0x88, 0, 0xCA, 0xDE, 'W', 'A', 'V', 'E', 0x23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
/* Frame sequence number, incremented after each transmission. */
@@ -127,9 +125,9 @@
static double tof;
-uint16_t anchor_dist_last_frm[TAG_NUM_IN_SYS];
-uint8_t tag_id = 0;
-uint8_t tag_id_recv = 0;
+uint32_t anchor_dist_last_frm[TAG_NUM_IN_SYS];
+uint32_t tag_id = 0;
+uint32_t tag_id_recv = 0;
uint8_t random_delay_tim = 0;
double distance, dist_no_bias, dist_cm;
@@ -138,7 +136,7 @@
float dis_after_filter; //当前距离值
LPFilter_Frac* p_Dis_Filter; //测距用的低通滤波器
-uint16_t g_Tagdist[256];
+uint16_t g_Tagdist[TOTAL_TAG_NUM];
uint8_t g_flag_Taggetdist[256];
/*------------------------------------ Functions ------------------------------------------*/
@@ -263,45 +261,78 @@
}
void Dw1000_App_Init(void)
{
- g_com_map[DEV_ID]=0x00;
+//g_com_map[DEV_ID] = 0x0b;
tx_poll_msg[MESSAGE_TYPE_IDX]=POLL;
tx_resp_msg[MESSAGE_TYPE_IDX]=RESPONSE;
tx_final_msg[MESSAGE_TYPE_IDX]=FINAL;
- memcpy(&tx_poll_msg[TAG_ID_IDX], &g_com_map[DEV_ID], 2);
- memcpy(&tx_final_msg[TAG_ID_IDX], &g_com_map[DEV_ID], 2);
- memcpy(&tx_resp_msg[ANCHOR_ID_IDX], &g_com_map[DEV_ID], 2);
+ memcpy(&tx_poll_msg[TAG_ID_IDX], &dev_id, 4);
+ memcpy(&tx_final_msg[TAG_ID_IDX], &dev_id, 4);
+ memcpy(&tx_resp_msg[ANCHOR_ID_IDX], &dev_id, 4);
}
+uint16_t Checksum_u16(uint8_t* pdata, uint32_t len)
+{
+ uint16_t sum = 0;
+ uint32_t i;
+ for(i=0; i<len; i++)
+ sum += pdata[i];
+ sum = ~sum;
+ return sum;
+}
+
+u16 tag_time_recv[TOTAL_TAG_NUM];
+u8 usart_send[25];
+u8 battary,button;
+extern uint8_t g_pairstart;
void tag_sleep_configuraion(void)
{
dwt_configuresleep(0x940, 0x7);
dwt_entersleep();
}
+uint16_t g_Resttimer;
uint8_t result;
+u8 tag_succ_times=0;
+u32 hex_dist;
+u16 checksum;
void Tag_App(void)//发送模式(TAG标签)
{
uint32_t frame_len;
uint32_t final_tx_time;
-
+ u32 start_poll;
+ u8 i;
+ LED0_ON;
+ g_Resttimer=0;
GPIO_ResetBits(SPIx_GPIO, SPIx_CS);
- delay_us(250);
+ delay_us(2500);
GPIO_SetBits(SPIx_GPIO, SPIx_CS);
-
+ tag_succ_times = 0;
+ tx_poll_msg[BATTARY_IDX] = Get_Battary();
+ tx_poll_msg[BUTTON_IDX] = !READ_KEY0;
+ for(i=0;i<REPOET_ANC_NUM;i++)
+ {
/* Write frame data to DW1000 and prepare transmission. See NOTE 7 below. */
- tx_poll_msg[ALL_MSG_SN_IDX] = frame_seq_nb;
+ tx_poll_msg[ANC_TYPE_IDX] = i;
+
dwt_writetxdata(sizeof(tx_poll_msg), tx_poll_msg, 0);//将Poll包数据传给DW1000，将在开启发送时传出去
dwt_writetxfctrl(sizeof(tx_poll_msg), 0);//设置超宽带发送数据长度
/* Start transmission, indicating that a response is expected so that reception is enabled automatically after the frame is sent and the delay
* set by dwt_setrxaftertxdelay() has elapsed. */
dwt_starttx(DWT_START_TX_IMMEDIATE | DWT_RESPONSE_EXPECTED);//开启发送，发送完成后等待一段时间开启接收，等待时间在dwt_setrxaftertxdelay中设置
-
+ start_poll = time32_incr;
/* We assume that the transmission is achieved correctly, poll for reception of a frame or error/timeout. See NOTE 8 below. */
while (!((status_reg = dwt_read32bitreg(SYS_STATUS_ID)) & (SYS_STATUS_RXFCG | SYS_STATUS_ALL_RX_ERR)))//不断查询芯片状态直到成功接收或者发生错误
- { };
+ { if(time32_incr - start_poll>20)
+ NVIC_SystemReset();
+ UART_CheckReceive();
+ UART_CheckSend();
+ };
/* Increment frame sequence number after transmission of the poll message (modulo 256). */
- frame_seq_nb++;
+ if(status_reg==0xffffffff)
+ {
+ NVIC_SystemReset();
+ }
if (status_reg & SYS_STATUS_RXFCG)//如果成功接收
{
@@ -316,15 +347,15 @@
/* Check that the frame is the expected response from the companion "DS TWR responder" example.
* As the sequence number field of the frame is not relevant, it is cleared to simplify the validation of the frame. */
- rx_buffer[ALL_MSG_SN_IDX] = 0;
- if (rx_buffer[MESSAGE_TYPE_IDX] == RESPONSE) //判断接收到的数据是否是response数据
+
+ if (rx_buffer[MESSAGE_TYPE_IDX] == RESPONSE&&!memcmp(&rx_buffer[TAG_ID_IDX],&dev_id,4)) //判断接收到的数据是否是response数据
{
/* Retrieve poll transmission and response reception timestamp. */
poll_tx_ts = get_tx_timestamp_u64(); //获得POLL发送时间T1
resp_rx_ts = get_rx_timestamp_u64(); //获得RESPONSE接收时间T4
- memcpy(&anchor_dist_last_frm[tag_id], &rx_buffer[DIST_IDX], 2);
- memcpy(&tx_final_msg[ANCHOR_ID_IDX], &rx_buffer[ANCHOR_ID_IDX], 2);
+ memcpy(&anchor_dist_last_frm[tag_id], &rx_buffer[DIST_IDX], 4);
+ memcpy(&tx_final_msg[ANCHOR_ID_IDX], &rx_buffer[ANCHOR_ID_IDX], 4);
/* Compute final message transmission time. See NOTE 9 below. */
final_tx_time = (resp_rx_ts + (RESP_RX_TO_FINAL_TX_DLY_UUS * UUS_TO_DWT_TIME)) >> 8;//计算final包发送时间，T5=T4+Treply2
dwt_setdelayedtrxtime(final_tx_time);//设置final包发送时间T5
@@ -338,11 +369,12 @@
final_msg_set_ts(&tx_final_msg[FINAL_MSG_FINAL_TX_TS_IDX], final_tx_ts);
/* Write and send final message. See NOTE 7 below. */
- tx_final_msg[ALL_MSG_SN_IDX] = frame_seq_nb;
+
dwt_writetxdata(sizeof(tx_final_msg), tx_final_msg, 0);//将发送数据写入DW1000
dwt_writetxfctrl(sizeof(tx_final_msg), 0);//设定发送数据长度
result=dwt_starttx(DWT_START_TX_DELAYED);//设定为延迟发送
+ tag_succ_times++;
/* Poll DW1000 until TX frame sent event set. See NOTE 8 below. */
if(result==0)
@@ -353,7 +385,7 @@
dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_TXFRS);//清除标志位
/* Increment frame sequence number after transmission of the final message (modulo 256). */
- frame_seq_nb++;
+
random_delay_tim = 0;
}
else
@@ -367,9 +399,17 @@
dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_ALL_RX_ERR);
random_delay_tim = DFT_RAND_DLY_TIM_MS;
}
- LED0_BLINK;
- /* Execute a delay between ranging exchanges. */
+// deca_sleep(10);
+}
dwt_entersleep();
+ if(tag_succ_times<REPOET_ANC_NUM_MIN)
+ {
+ random_delay_tim =time32_incr&0x8f+7;
+ deca_sleep(random_delay_tim);
+ }
+ LED0_BLINK;
+ RTC_SET_ALARM(1);
+ /* Execute a delay between ranging exchanges. */
}
@@ -389,10 +429,11 @@
{
UART_CheckReceive();
UART_CheckSend();
+ g_Resttimer=0;
};
if (status_reg & SYS_STATUS_RXFCG)//成功接收
- {
+ { u16 tag_recv_interval;
/* Clear good RX frame event in the DW1000 status register. */
dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_RXFCG);//清除标志位
@@ -404,14 +445,20 @@
/* Check that the frame is a poll sent by "DS TWR initiator" example.
* As the sequence number field of the frame is not relevant, it is cleared to simplify the validation of the frame. */
- rx_buffer[ALL_MSG_SN_IDX] = 0;
+
//将收到的tag_id分别写入各次通讯的包中，为多标签通讯服务，防止一次通讯中接收到不同ID标签的数据
- tag_id_recv = rx_buffer[TAG_ID_IDX];
- tx_resp_msg[TAG_ID_IDX] = tag_id_recv;
-
+ //tag_id_recv = rx_buffer[TAG_ID_IDX];
+ memcpy(&tag_id_recv,&rx_buffer[TAG_ID_IDX],4);
+ memcpy(&tx_resp_msg[TAG_ID_IDX],&tag_id_recv,4);
+ //tx_resp_msg[TAG_ID_IDX] = tag_id_recv;
+// if(tag_recv_timer>tag_time_recv[tag_id_recv-TAG_ID_START])
+// { tag_recv_interval = tag_recv_timer - tag_time_recv[tag_id_recv];
+// }else{
+// tag_recv_interval = tag_recv_timer + 65535 - tag_time_recv[tag_id_recv];
+// }
- if (rx_buffer[MESSAGE_TYPE_IDX] == POLL) //判断是否是poll包数据
+ if (rx_buffer[MESSAGE_TYPE_IDX] == POLL&&(anchor_type == rx_buffer[ANC_TYPE_IDX])) //判断是否是poll包数据
{
/* Retrieve poll reception timestamp. */
poll_rx_ts = get_rx_timestamp_u64();//获得Poll包接收时间T2
@@ -425,12 +472,15 @@
dwt_setrxtimeout(FINAL_RX_TIMEOUT_UUS);//接收超时时间
/* Write and send the response message. See NOTE 9 below.*/
- memcpy(&tx_resp_msg[DIST_IDX], &anchor_dist_last_frm[tag_id_recv], 2);
- tx_resp_msg[ALL_MSG_SN_IDX] = frame_seq_nb;
+ if(tag_id_recv-TAG_ID_START<=TOTAL_TAG_NUM)
+ memcpy(&tx_resp_msg[DIST_IDX], &anchor_dist_last_frm[tag_id_recv-TAG_ID_START], 4);
+
dwt_writetxdata(sizeof(tx_resp_msg), tx_resp_msg, 0);//写入发送数据
dwt_writetxfctrl(sizeof(tx_resp_msg), 0);//设定发送长度
result = dwt_starttx(DWT_START_TX_DELAYED | DWT_RESPONSE_EXPECTED);//延迟发送，等待接收
+ battary = rx_buffer[BATTARY_IDX];
+ button = rx_buffer[BUTTON_IDX];
/* We assume that the transmission is achieved correctly, now poll for reception of expected "final" frame or error/timeout.
* See NOTE 7 below. */
if(result==0)
@@ -439,7 +489,6 @@
{ };
}
/* Increment frame sequence number after transmission of the response message (modulo 256). */
- frame_seq_nb++;
if (status_reg & SYS_STATUS_RXFCG)//接收成功
{
@@ -454,14 +503,14 @@
/* Check that the frame is a final message sent by "DS TWR initiator" example.
* As the sequence number field of the frame is not used in this example, it can be zeroed to ease the validation of the frame. */
- rx_buffer[ALL_MSG_SN_IDX] = 0;
- if (rx_buffer[MESSAGE_TYPE_IDX] == FINAL&&rx_buffer[TAG_ID_IDX]==tag_id_recv&&rx_buffer[ANCHOR_ID_IDX]==g_com_map[DEV_ID]) //判断是否为Final包
+
+ if (rx_buffer[MESSAGE_TYPE_IDX] == FINAL&&!memcmp(&rx_buffer[TAG_ID_IDX],&tag_id_recv,4)&&!memcmp(&rx_buffer[ANCHOR_ID_IDX],&dev_id,4)) //判断是否为Final包
{
uint32_t poll_tx_ts, resp_rx_ts, final_tx_ts;
uint32_t poll_rx_ts_32, resp_tx_ts_32, final_rx_ts_32;
double Ra, Rb, Da, Db;
int64_t tof_dtu;
-
+
/* Retrieve response transmission and final reception timestamps. */
resp_tx_ts = get_tx_timestamp_u64();//获得response发送时间T3
final_rx_ts = get_rx_timestamp_u64();//获得final接收时间T6
@@ -492,14 +541,43 @@
LED0_BLINK; //每成功一次通讯则闪烁一次
g_UWB_com_interval = 0;
dis_after_filter=dist_cm;
- g_Tagdist[tag_id_recv]=dist_cm;
- g_flag_Taggetdist[tag_id_recv]=0;
+ // g_Tagdist[tag_id_recv-TAG_ID_START]=dist_cm;
+// if(g_pairstart==1&&dist_cm<20)
+// {
+// g_pairstart=0;
+// g_com_map[PAIR_ID]=tag_id_recv;
+// save_com_map_to_flash();
+// BEEP2_ON;
+// delay_ms(1000);
+// printf("Pair Finish PairID: %d. \r\n",g_com_map[PAIR_ID]);
+// }
+ // tag_time_recv[tag_id_recv] = tag_recv_timer;
+ if(tag_id_recv-TAG_ID_START<=TOTAL_TAG_NUM)
+ {
+ g_flag_Taggetdist[tag_id_recv-TAG_ID_START]=0;
+ anchor_dist_last_frm[tag_id_recv-TAG_ID_START] = dist_cm;
+ }
+ #ifdef HEX_OUTPUT
+ usart_send[2] = frame_seq_nb++;
+ //usart_send[6] = tag_id_recv;
+ //usart_send[8] = g_com_map[DEV_ID];
+ memcpy(&usart_send[3],&tag_id_recv,4);
+ memcpy(&usart_send[7],&dev_id,4);
+ hex_dist = dist_cm;
+ memcpy(&usart_send[11],&hex_dist,4);
+ usart_send[15] = battary;
+ usart_send[16] = button;
+ checksum = Checksum_u16(&usart_send[2],19);
+ memcpy(&usart_send[21],&checksum,2);
+ UART_PushFrame(usart_send,23);
+ #else
+ printf("Anchor ID: %d, Tag ID: %d, Dist = %d cm\n", g_com_map[DEV_ID_L]|g_com_map[DEV_ID_L]<<8, tag_id_recv, (uint16_t)dist_cm);
+ #endif
+
//dis_after_filter = LP_Frac_Update(p_Dis_Filter, dist_cm);
}
- }
- else
- {
+ }else{
/* Clear RX error events in the DW1000 status register. */
dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_ALL_RX_ERR);
}
@@ -512,66 +590,3 @@
}
}
-/*****************************************************************************************************************************************************
- * NOTES:
- *
- * 1. The sum of the values is the TX to RX antenna delay, experimentally determined by a calibration process. Here we use a hard coded typical value
- * but, in a real application, each device should have its own antenna delay properly calibrated to get the best possible precision when performing
- * range measurements.
- * 2. The messages here are similar to those used in the DecaRanging ARM application (shipped with EVK1000 kit). They comply with the IEEE
- * 802.15.4 standard MAC data frame encoding and they are following the ISO/IEC:24730-62:2013 standard. The messages used are:
- * - a poll message sent by the initiator to trigger the ranging exchange.
- * - a response message sent by the responder allowing the initiator to go on with the process
- * - a final message sent by the initiator to complete the exchange and provide all information needed by the responder to compute the
- * time-of-flight (distance) estimate.
- * The first 10 bytes of those frame are common and are composed of the following fields:
- * - byte 0/1: frame control (0x8841 to indicate a data frame using 16-bit addressing).
- * - byte 2: sequence number, incremented for each new frame.
- * - byte 3/4: PAN TAG_ID (0xDECA).
- * - byte 5/6: destination address, see NOTE 3 below.
- * - byte 7/8: source address, see NOTE 3 below.
- * - byte 9: function code (specific values to indicate which message it is in the ranging process).
- * The remaining bytes are specific to each message as follows:
- * Poll message:
- * - no more data
- * Response message:
- * - byte 10: activity code (0x02 to tell the initiator to go on with the ranging exchange).
- * - byte 11/12: activity parameter, not used here for activity code 0x02.
- * Final message:
- * - byte 10 -> 13: poll message transmission timestamp.
- * - byte 14 -> 17: response message reception timestamp.
- * - byte 18 -> 21: final message transmission timestamp.
- * All messages end with a 2-byte checksum automatically set by DW1000.
- * 3. Source and destination addresses are hard coded constants in this example to keep it simple but for a real product every device should have a
- * unique TAG_ID. Here, 16-bit addressing is used to keep the messages as short as possible but, in an actual application, this should be done only
- * after an exchange of specific messages used to define those short addresses for each device participating to the ranging exchange.
- * 4. Delays between frames have been chosen here to ensure proper synchronisation of transmission and reception of the frames between the initiator
- * and the responder and to ensure a correct accuracy of the computed distance. The user is referred to DecaRanging ARM Source Code Guide for more
- * details about the timings involved in the ranging process.
- * 5. This timeout is for complete reception of a frame, i.e. timeout duration must take into account the length of the expected frame. Here the value
- * is arbitrary but chosen large enough to make sure that there is enough time to receive the complete response frame sent by the responder at the
- * 110k data rate used (around 3 ms).
- * 6. In a real application, for optimum performance within regulatory limits, it may be necessary to set TX pulse bandwidth and TX power, (using
- * the dwt_configuretxrf API call) to per device calibrated values saved in the target system or the DW1000 OTP memory.
- * 7. dwt_writetxdata() takes the full size of the message as a parameter but only copies (size - 2) bytes as the check-sum at the end of the frame is
- * automatically appended by the DW1000. This means that our variable could be two bytes shorter without losing any data (but the sizeof would not
- * work anymore then as we would still have to indicate the full length of the frame to dwt_writetxdata()). It is also to be noted that, when using
- * delayed send, the time set for transmission must be far enough in the future so that the DW1000 IC has the time to process and start the
- * transmission of the frame at the wanted time. If the transmission command is issued too late compared to when the frame is supposed to be sent,
- * this is indicated by an error code returned by dwt_starttx() API call. Here it is not tested, as the values of the delays between frames have
- * been carefully defined to avoid this situation.
- * 8. We use polled mode of operation here to keep the example as simple as possible but all status events can be used to generate interrupts. Please
- * refer to DW1000 User Manual for more details on "interrupts". It is also to be noted that STATUS register is 5 bytes long but, as the event we
- * use are all in the first bytes of the register, we can use the simple dwt_read32bitreg() API call to access it instead of reading the whole 5
- * bytes.
- * 9. As we want to send final TX timestamp in the final message, we have to compute it in advance instead of relying on the reading of DW1000
- * register. Timestamps and delayed transmission time are both expressed in device time units so we just have to add the desired response delay to
- * response RX timestamp to get final transmission time. The delayed transmission time resolution is 512 device time units which means that the
- * lower 9 bits of the obtained value must be zeroed. This also allows to encode the 40-bit value in a 32-bit words by shifting the all-zero lower
- * 8 bits.
- * 10. In this operation, the high order byte of each 40-bit timestamps is discarded. This is acceptable as those time-stamps are not separated by
- * more than 2**32 device time units (which is around 67 ms) which means that the calculation of the round-trip delays (needed in the
- * time-of-flight computation) can be handled by a 32-bit subtraction.
- * 11. The user is referred to DecaRanging ARM application (distributed with EVK1000 product) for additional practical example of usage, and to the
- * DW1000 API Guide for more details on the DW1000 driver functions.
- ****************************************************************************************************************************************************/
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