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/*! ----------------------------------------------------------------------------
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* @file main.c
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* @brief Double-sided two-way ranging (DS TWR) initiator example code
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*
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* This is a simple code example which acts as the initiator in a DS TWR distance measurement exchange. This application sends a "poll"
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* frame (recording the TX time-stamp of the poll), and then waits for a "response" message expected from the "DS TWR responder" example
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* code (companion to this application). When the response is received its RX time-stamp is recorded and we send a "final" message to
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* complete the exchange. The final message contains all the time-stamps recorded by this application, including the calculated/predicted TX
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* time-stamp for the final message itself. The companion "DS TWR responder" example application works out the time-of-flight over-the-air
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* and, thus, the estimated distance between the two devices.
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*
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* @attention
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*
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* Copyright 2015 (c) Decawave Ltd, Dublin, Ireland.
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*
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* All rights reserved.
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*
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* @author Decawave
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*/
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#include <string.h>
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#include "dw_app.h"
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#include "deca_device_api.h"
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#include "deca_regs.h"
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#include "dw_driver.h"
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#include "Spi.h"
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#include "led.h"
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/*------------------------------------ Marcos ------------------------------------------*/
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/* Inter-ranging delay period, in milliseconds. */
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#define RNG_DELAY_MS 100
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/* Default antenna delay values for 64 MHz PRF. See NOTE 1 below. */
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#define TX_ANT_DLY 0
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#define RX_ANT_DLY 32899
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/* UWB microsecond (uus) to device time unit (dtu, around 15.65 ps) conversion factor.
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* 1 uus = 512 / 499.2 µs and 1 µs = 499.2 * 128 dtu. */
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#define UUS_TO_DWT_TIME 65536
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/* Delay between frames, in UWB microseconds. See NOTE 4 below. */
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/* 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. */
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#define POLL_TX_TO_RESP_RX_DLY_UUS 150
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/* 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
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* frame length of approximately 2.66 ms with above configuration. */
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#define RESP_RX_TO_FINAL_TX_DLY_UUS 4100
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/* Receive response timeout. See NOTE 5 below. */
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#define RESP_RX_TIMEOUT_UUS 14700
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#define POLL_RX_TO_RESP_TX_DLY_UUS 3600
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/* 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. */
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#define RESP_TX_TO_FINAL_RX_DLY_UUS 500
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/* Receive final timeout. See NOTE 5 below. */
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#define FINAL_RX_TIMEOUT_UUS 4300
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#define SPEED_OF_LIGHT 299702547
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/* Indexes to access some of the fields in the frames defined above. */
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#define ALL_MSG_SN_IDX 2
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#define FINAL_MSG_POLL_TX_TS_IDX 10
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#define FINAL_MSG_RESP_RX_TS_IDX 14
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#define FINAL_MSG_FINAL_TX_TS_IDX 18
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#define FINAL_MSG_TS_LEN 4
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#define GROUP_ID_IDX 0
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#define SOURCE_ID_IDX 1
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#define MESSAGE_TYPE_IDX 3
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#define POLL 0x01
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#define RESPONSE 0x02
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#define FINAL 0x03
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/*------------------------------------ Variables ------------------------------------------*/
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/* Default communication configuration. We use here EVK1000's default mode (mode 3). */
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static dwt_config_t config =
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{
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2, /* Channel number. */
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DWT_PRF_64M, /* Pulse repetition frequency. */
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DWT_PLEN_1024, /* Preamble length. */
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DWT_PAC32, /* Preamble acquisition chunk size. Used in RX only. */
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9, /* TX preamble code. Used in TX only. */
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9, /* RX preamble code. Used in RX only. */
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1, /* Use non-standard SFD (Boolean) */
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DWT_BR_110K, /* Data rate. */
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DWT_PHRMODE_STD, /* PHY header mode. */
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(1025 + 64 - 32) /* SFD timeout (preamble length + 1 + SFD length - PAC size). Used in RX only. */
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};
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/* Frames used in the ranging process. See NOTE 2 below. */
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static uint8 tx_poll_msg[] = {0x00, 0x88, 0, 0xCA, 0xDE, 'W', 'A', 'V', 'E', 0x21, 0, 0};
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//static uint8 rx_resp_msg[] = {0x41, 0x88, 0, 0xCA, 0xDE, 'V', 'E', 'W', 'A', 0x10, 0x02, 0, 0, 0, 0};
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static uint8 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};
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//static uint8 rx_poll_msg[] = {0x00, 0x88, 0, 0xCA, 0xDE, 'W', 'A', 'V', 'E', 0x21, 0, 0};
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static uint8 tx_resp_msg[] = {0x41, 0x88, 0, 0xCA, 0xDE, 'V', 'E', 'W', 'A', 0x10, 0x02, 0, 0, 0, 0};
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//static uint8 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};
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/* Frame sequence number, incremented after each transmission. */
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static uint32 frame_seq_nb = 0;
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/* Hold copy of status register state here for reference, so reader can examine it at a breakpoint. */
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static uint32 status_reg = 0;
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/* Buffer to store received response message.
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* Its size is adjusted to longest frame that this example code is supposed to handle. */
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#define RX_BUF_LEN 24
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static uint8 rx_buffer[RX_BUF_LEN];
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/* Time-stamps of frames transmission/reception, expressed in device time units.
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* As they are 40-bit wide, we need to define a 64-bit int type to handle them. */
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typedef unsigned long long uint64;
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static uint64 poll_tx_ts;
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static uint64 resp_rx_ts;
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static uint64 final_tx_ts;
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/* Length of the common part of the message (up to and including the function code, see NOTE 2 below). */
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typedef signed long long int64;
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static uint64 poll_rx_ts;
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static uint64 resp_tx_ts;
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static uint64 final_rx_ts;
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static double tof;
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uint16_t anchor_dist_last_frm[TAG_NUM_IN_SYS];
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uint8_t tag_id = 0;
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uint8_t tag_id_recv = 0;
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uint8_t random_delay_tim = 0;
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double distance, dist_no_bias, dist_cm;
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/*------------------------------------ Functions ------------------------------------------*/
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/*! ------------------------------------------------------------------------------------------------------------------
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* @fn get_tx_timestamp_u64()
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*
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* @brief Get the TX time-stamp in a 64-bit variable.
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* /!\ This function assumes that length of time-stamps is 40 bits, for both TX and RX!
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*
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* @param none
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*
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* @return 64-bit value of the read time-stamp.
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*/
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static uint64 get_tx_timestamp_u64(void)
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{
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uint8 ts_tab[5];
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uint64 ts = 0;
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int i;
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dwt_readtxtimestamp(ts_tab);
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for (i = 4; i >= 0; i--)
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{
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ts <<= 8;
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ts |= ts_tab[i];
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}
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return ts;
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}
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/*! ------------------------------------------------------------------------------------------------------------------
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* @fn get_rx_timestamp_u64()
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*
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* @brief Get the RX time-stamp in a 64-bit variable.
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* /!\ This function assumes that length of time-stamps is 40 bits, for both TX and RX!
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*
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* @param none
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*
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* @return 64-bit value of the read time-stamp.
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*/
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static uint64 get_rx_timestamp_u64(void)
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{
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uint8 ts_tab[5];
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uint64 ts = 0;
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int i;
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dwt_readrxtimestamp(ts_tab);
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for (i = 4; i >= 0; i--)
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{
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ts <<= 8;
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ts |= ts_tab[i];
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}
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return ts;
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}
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/*! ------------------------------------------------------------------------------------------------------------------
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* @fn final_msg_set_ts()
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*
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* @brief Fill a given timestamp field in the final message with the given value. In the timestamp fields of the final
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* message, the least significant byte is at the lower address.
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*
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* @param ts_field pointer on the first byte of the timestamp field to fill
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* ts timestamp value
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*
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* @return none
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*/
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static void final_msg_set_ts(uint8 *ts_field, uint64 ts)
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{
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int i;
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for (i = 0; i < FINAL_MSG_TS_LEN; i++)
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{
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ts_field[i] = (uint8) ts;
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ts >>= 8;
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}
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}
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static void final_msg_get_ts(const uint8 *ts_field, uint32 *ts)
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{
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int i;
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*ts = 0;
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for (i = 0; i < FINAL_MSG_TS_LEN; i++)
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{
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*ts += ts_field[i] << (i * 8);
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}
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}
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void Dw1000_Init(void)
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{
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/* Reset and initialise DW1000.
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* For initialisation, DW1000 clocks must be temporarily set to crystal speed. After initialisation SPI rate can be increased for optimum
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* performance. */
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Reset_DW1000();//ÖØÆôDW1000 /* Target specific drive of RSTn line into DW1000 low for a period. */
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dwt_initialise(DWT_LOADUCODE);//³õʼ»¯DW1000
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Spi_ChangePrescaler(SPIx_PRESCALER_FAST); //ÉèÖÃΪ¿ìËÙģʽ
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/* Configure DW1000. See NOTE 6 below. */
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dwt_configure(&config);//ÅäÖÃDW1000
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/* Apply default antenna delay value. See NOTE 1 below. */
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dwt_setrxantennadelay(RX_ANT_DLY); //ÉèÖýÓÊÕÌìÏßÑÓ³Ù
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dwt_settxantennadelay(TX_ANT_DLY); //ÉèÖ÷¢ÉäÌìÏßÑÓ³Ù
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/* Set expected response's delay and timeout. See NOTE 4 and 5 below.
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* As this example only handles one incoming frame with always the same delay and timeout, those values can be set here once for all. */
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dwt_setrxaftertxdelay(POLL_TX_TO_RESP_RX_DLY_UUS); //ÉèÖ÷¢Ëͺó¿ªÆô½ÓÊÕ£¬²¢É趨ÑÓ³Ùʱ¼ä
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dwt_setrxtimeout(RESP_RX_TIMEOUT_UUS); //ÉèÖýÓÊÕ³¬Ê±Ê±¼ä
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}
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void Tag_App(void)//·¢ËÍģʽ(TAG±êÇ©)
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{
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uint32 frame_len;
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uint32 final_tx_time;
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/* Write frame data to DW1000 and prepare transmission. See NOTE 7 below. */
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tx_poll_msg[ALL_MSG_SN_IDX] = frame_seq_nb;
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dwt_writetxdata(sizeof(tx_poll_msg), tx_poll_msg, 0);//½«Poll°üÊý¾Ý´«¸øDW1000£¬½«ÔÚ¿ªÆô·¢ËÍʱ´«³öÈ¥
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dwt_writetxfctrl(sizeof(tx_poll_msg), 0);//ÉèÖó¬¿í´ø·¢ËÍÊý¾Ý³¤¶È
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/* Start transmission, indicating that a response is expected so that reception is enabled automatically after the frame is sent and the delay
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* set by dwt_setrxaftertxdelay() has elapsed. */
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dwt_starttx(DWT_START_TX_IMMEDIATE | DWT_RESPONSE_EXPECTED);//¿ªÆô·¢ËÍ£¬·¢ËÍÍê³ÉºóµÈ´ýÒ»¶Îʱ¼ä¿ªÆô½ÓÊÕ£¬µÈ´ýʱ¼äÔÚdwt_setrxaftertxdelayÖÐÉèÖÃ
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/* We assume that the transmission is achieved correctly, poll for reception of a frame or error/timeout. See NOTE 8 below. */
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while (!((status_reg = dwt_read32bitreg(SYS_STATUS_ID)) & (SYS_STATUS_RXFCG | SYS_STATUS_ALL_RX_ERR)))//²»¶Ï²éѯоƬ״ֱ̬µ½³É¹¦½ÓÊÕ»òÕß·¢Éú´íÎó
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{ };
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/* Increment frame sequence number after transmission of the poll message (modulo 256). */
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frame_seq_nb++;
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if (status_reg & SYS_STATUS_RXFCG)//Èç¹û³É¹¦½ÓÊÕ
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{
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/* Clear good RX frame event and TX frame sent in the DW1000 status register. */
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dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_RXFCG | SYS_STATUS_TXFRS);//Çå³þ¼Ä´æÆ÷±ê־λ
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/* A frame has been received, read it into the local buffer. */
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frame_len = dwt_read32bitreg(RX_FINFO_ID) & RX_FINFO_RXFLEN_MASK; //»ñµÃ½ÓÊÕµ½µÄÊý¾Ý³¤¶È
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dwt_readrxdata(rx_buffer, frame_len, 0); //¶ÁÈ¡½ÓÊÕÊý¾Ý
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/* Check that the frame is the expected response from the companion "DS TWR responder" example.
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* As the sequence number field of the frame is not relevant, it is cleared to simplify the validation of the frame. */
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rx_buffer[ALL_MSG_SN_IDX] = 0;
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if (rx_buffer[9] == 0x10) //ÅжϽÓÊÕµ½µÄÊý¾ÝÊÇ·ñÊÇresponseÊý¾Ý
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{
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/* Retrieve poll transmission and response reception timestamp. */
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poll_tx_ts = get_tx_timestamp_u64(); //»ñµÃPOLL·¢ËÍʱ¼äT1
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resp_rx_ts = get_rx_timestamp_u64(); //»ñµÃRESPONSE½ÓÊÕʱ¼äT4
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memcpy(&anchor_dist_last_frm[tag_id], &rx_buffer[11], 2);
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/* Compute final message transmission time. See NOTE 9 below. */
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final_tx_time = (resp_rx_ts + (RESP_RX_TO_FINAL_TX_DLY_UUS * UUS_TO_DWT_TIME)) >> 8;//¼ÆËãfinal°ü·¢ËÍʱ¼ä£¬T5=T4+Treply2
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dwt_setdelayedtrxtime(final_tx_time);//ÉèÖÃfinal°ü·¢ËÍʱ¼äT5
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/* Final TX timestamp is the transmission time we programmed plus the TX antenna delay. */
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final_tx_ts = (((uint64)(final_tx_time & 0xFFFFFFFE)) << 8) + TX_ANT_DLY;//final°üʵ¼Ê·¢ËÍʱ¼äÊǼÆËãʱ¼ä¼ÓÉÏ·¢ËÍÌìÏßdelay
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/* Write all timestamps in the final message. See NOTE 10 below. */
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final_msg_set_ts(&tx_final_msg[FINAL_MSG_POLL_TX_TS_IDX], poll_tx_ts);//½«T1£¬T4£¬T5дÈë·¢ËÍÊý¾Ý
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final_msg_set_ts(&tx_final_msg[FINAL_MSG_RESP_RX_TS_IDX], resp_rx_ts);
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final_msg_set_ts(&tx_final_msg[FINAL_MSG_FINAL_TX_TS_IDX], final_tx_ts);
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/* Write and send final message. See NOTE 7 below. */
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tx_final_msg[ALL_MSG_SN_IDX] = frame_seq_nb;
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dwt_writetxdata(sizeof(tx_final_msg), tx_final_msg, 0);//½«·¢ËÍÊý¾ÝдÈëDW1000
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dwt_writetxfctrl(sizeof(tx_final_msg), 0);//É趨·¢ËÍÊý¾Ý³¤¶È
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dwt_starttx(DWT_START_TX_DELAYED);//É趨ΪÑÓ³Ù·¢ËÍ
|
|
//ÕâÀïΪ´®¿ÚÊä³ö
|
// if (GPIO_ReadInputDataBit(GPIOA, SW2) != RESET) //ͨ¹ý²¦Â뿪¹ØÅжÏÊý¾ÝÊä³ö¸ñʽ
|
// {
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// dID = TAG_ID;
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// printf("TAG_ID: %2.0f ", dID);
|
// dID = ANCHOR_ID;
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// printf("ANCHOR_ID: %2.0f ", dID);
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// printf("Distance: %5.0f cm\n", (double)dist[TAG_ID]);
|
// }
|
// else
|
// {
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// send[2] = ANCHOR_ID;
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// send[3] = TAG_ID;
|
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// memcpy(&send[4], &dist[TAG_ID], 2);
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// check = Checksum_u16(&send[2], 6);
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// memcpy(&send[8], &check, 2);
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// USART_puts(send, 10);
|
// }
|
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/* Poll DW1000 until TX frame sent event set. See NOTE 8 below. */
|
while (!(dwt_read32bitreg(SYS_STATUS_ID) & SYS_STATUS_TXFRS))//²»¶Ï²éѯоƬ״ֱ̬µ½·¢ËÍÍê³É
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{ };
|
|
/* Clear TXFRS event. */
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dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_TXFRS);//Çå³ý±ê־λ
|
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/* Increment frame sequence number after transmission of the final message (modulo 256). */
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frame_seq_nb++;
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random_delay_tim = 0;
|
}
|
else
|
{
|
random_delay_tim = DFT_RAND_DLY_TIM_MS; //Èç¹ûͨѶʧ°Ü£¬½«¼ä¸ôʱ¼äÔö¼Ó5ms£¬±Ü¿ªÒòΪ¶à±êǩͬʱ·¢ËÍÒýÆðµÄ³åÍ»¡£
|
}
|
}
|
else
|
{
|
/* Clear RX error events in the DW1000 status register. */
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dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_ALL_RX_ERR);
|
random_delay_tim = DFT_RAND_DLY_TIM_MS;
|
}
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LED0_BLINK;
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/* Execute a delay between ranging exchanges. */
|
deca_sleep(RNG_DELAY_MS + random_delay_tim); //ÐÝÃ߹̶¨Ê±¼ä
|
}
|
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void Anchor_App(void)
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{
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uint32 frame_len;
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uint32 resp_tx_time;
|
|
/* Clear reception timeout to start next ranging process. */
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dwt_setrxtimeout(0);//É趨½ÓÊÕ³¬Ê±Ê±¼ä£¬0λûÓг¬Ê±Ê±¼ä
|
|
/* Activate reception immediately. */
|
dwt_rxenable(0);//´ò¿ª½ÓÊÕ
|
|
/* Poll for reception of a frame or error/timeout. See NOTE 7 below. */
|
while (!((status_reg = dwt_read32bitreg(SYS_STATUS_ID)) & (SYS_STATUS_RXFCG | SYS_STATUS_ALL_RX_ERR)))//²»¶Ï²éѯоƬ״ֱ̬µ½½ÓÊճɹ¦»òÕß³öÏÖ´íÎó
|
{ };
|
|
if (status_reg & SYS_STATUS_RXFCG)//³É¹¦½ÓÊÕ
|
{
|
/* Clear good RX frame event in the DW1000 status register. */
|
dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_RXFCG);//Çå³ý±ê־λ
|
|
/* A frame has been received, read it into the local buffer. */
|
frame_len = dwt_read32bitreg(RX_FINFO_ID) & RX_FINFO_RXFL_MASK_1023;//»ñµÃ½ÓÊÕÊý¾Ý³¤¶È
|
|
dwt_readrxdata(rx_buffer, frame_len, 0);//¶ÁÈ¡½ÓÊÕÊý¾Ý
|
|
|
/* 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;
|
|
//½«ÊÕµ½µÄtag_id·Ö±ðдÈë¸÷´ÎͨѶµÄ°üÖУ¬Îª¶à±êǩͨѶ·þÎñ£¬·ÀÖ¹Ò»´ÎͨѶÖнÓÊÕµ½²»Í¬ID±êÇ©µÄÊý¾Ý
|
tag_id_recv = rx_buffer[5];
|
tx_resp_msg[5] = tag_id_recv;
|
|
|
if (rx_buffer[9] == 0x21) //ÅжÏÊÇ·ñÊÇpoll°üÊý¾Ý
|
{
|
/* Retrieve poll reception timestamp. */
|
poll_rx_ts = get_rx_timestamp_u64();//»ñµÃPoll°ü½ÓÊÕʱ¼äT2
|
|
/* Set send time for response. See NOTE 8 below. */
|
resp_tx_time = (poll_rx_ts + (POLL_RX_TO_RESP_TX_DLY_UUS * UUS_TO_DWT_TIME)) >> 8;//¼ÆËãResponse·¢ËÍʱ¼äT3¡£
|
dwt_setdelayedtrxtime(resp_tx_time);//ÉèÖÃResponse·¢ËÍʱ¼äT3
|
|
/* Set expected delay and timeout for final message reception. */
|
dwt_setrxaftertxdelay(RESP_TX_TO_FINAL_RX_DLY_UUS);//ÉèÖ÷¢ËÍÍê³Éºó¿ªÆô½ÓÊÕÑÓ³Ùʱ¼ä
|
dwt_setrxtimeout(FINAL_RX_TIMEOUT_UUS);//½ÓÊÕ³¬Ê±Ê±¼ä
|
|
/* Write and send the response message. See NOTE 9 below.*/
|
memcpy(&tx_resp_msg[11], &anchor_dist_last_frm[tag_id_recv], 2);
|
tx_resp_msg[ALL_MSG_SN_IDX] = frame_seq_nb;
|
dwt_writetxdata(sizeof(tx_resp_msg), tx_resp_msg, 0);//дÈë·¢ËÍÊý¾Ý
|
dwt_writetxfctrl(sizeof(tx_resp_msg), 0);//É趨·¢Ëͳ¤¶È
|
dwt_starttx(DWT_START_TX_DELAYED | DWT_RESPONSE_EXPECTED);//ÑÓ³Ù·¢ËÍ£¬µÈ´ý½ÓÊÕ
|
|
/* We assume that the transmission is achieved correctly, now poll for reception of expected "final" frame or error/timeout.
|
* See NOTE 7 below. */
|
while (!((status_reg = dwt_read32bitreg(SYS_STATUS_ID)) & (SYS_STATUS_RXFCG | SYS_STATUS_ALL_RX_ERR)))///²»¶Ï²éѯоƬ״ֱ̬µ½½ÓÊճɹ¦»òÕß³öÏÖ´íÎó
|
{ };
|
|
/* Increment frame sequence number after transmission of the response message (modulo 256). */
|
frame_seq_nb++;
|
|
if (status_reg & SYS_STATUS_RXFCG)//½ÓÊճɹ¦
|
{
|
/* Clear good RX frame event and TX frame sent in the DW1000 status register. */
|
dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_RXFCG | SYS_STATUS_TXFRS);//Çå³þ±ê־λ
|
|
/* A frame has been received, read it into the local buffer. */
|
frame_len = dwt_read32bitreg(RX_FINFO_ID) & RX_FINFO_RXFLEN_MASK;//Êý¾Ý³¤¶È
|
|
dwt_readrxdata(rx_buffer, frame_len, 0);//¶ÁÈ¡½ÓÊÕÊý¾Ý
|
|
|
/* 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[9] == 0x23) //ÅжÏÊÇ·ñΪFinal°ü
|
{
|
uint32 poll_tx_ts, resp_rx_ts, final_tx_ts;
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uint32 poll_rx_ts_32, resp_tx_ts_32, final_rx_ts_32;
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double Ra, Rb, Da, Db;
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int64_t tof_dtu;
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/* Retrieve response transmission and final reception timestamps. */
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resp_tx_ts = get_tx_timestamp_u64();//»ñµÃresponse·¢ËÍʱ¼äT3
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final_rx_ts = get_rx_timestamp_u64();//»ñµÃfinal½ÓÊÕʱ¼äT6
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/* Get timestamps embedded in the final message. */
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final_msg_get_ts(&rx_buffer[FINAL_MSG_POLL_TX_TS_IDX], &poll_tx_ts);//´Ó½ÓÊÕÊý¾ÝÖжÁÈ¡T1£¬T4£¬T5
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final_msg_get_ts(&rx_buffer[FINAL_MSG_RESP_RX_TS_IDX], &resp_rx_ts);
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final_msg_get_ts(&rx_buffer[FINAL_MSG_FINAL_TX_TS_IDX], &final_tx_ts);
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/* Compute time of flight. 32-bit subtractions give correct answers even if clock has wrapped. See NOTE 10 below. */
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poll_rx_ts_32 = (uint32)poll_rx_ts;//ʹÓÃ32λÊý¾Ý¼ÆËã
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resp_tx_ts_32 = (uint32)resp_tx_ts;
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final_rx_ts_32 = (uint32)final_rx_ts;
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Ra = (double)(resp_rx_ts - poll_tx_ts);//Tround1 = T4 - T1
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Rb = (double)(final_rx_ts_32 - resp_tx_ts_32);//Tround2 = T6 - T3
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Da = (double)(final_tx_ts - resp_rx_ts);//Treply2 = T5 - T4
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Db = (double)(resp_tx_ts_32 - poll_rx_ts_32);//Treply1 = T3 - T2
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tof_dtu = (int64)((Ra * Rb - Da * Db) / (Ra + Rb + Da + Db));//¼ÆË㹫ʽ
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tof = tof_dtu * DWT_TIME_UNITS;
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distance = tof * SPEED_OF_LIGHT;//¾àÀë=¹âËÙ*·ÉÐÐʱ¼ä
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dist_no_bias = distance - dwt_getrangebias(config.chan, (float)distance, config.prf); //¾àÀë¼õÈ¥½ÃÕýϵÊý
|
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dist_cm = dist_no_bias * 100; //dis Ϊµ¥Î»ÎªcmµÄ¾àÀë
|
// dist[TAG_ID] = LP(dis, TAG_ID); //LP ΪµÍͨÂ˲¨Æ÷£¬ÈÃÊý¾Ý¸üÎȶ¨
|
|
LED0_BLINK; //ÿ³É¹¦Ò»´ÎͨѶÔòÉÁ˸һ´Î
|
//ÕâÀ﹩´®¿ÚÊä³ö
|
// if (GPIO_ReadInputDataBit(GPIOA, SW2) != RESET) //ͨ¹ý²¦Â뿪¹ØÅжÏÊý¾ÝÊä³ö¸ñʽ
|
// {
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// dID = TAG_ID;
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// printf("TAG_ID: %2.0f ", dID);
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// dID = ANCHOR_ID;
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// printf("ANCHOR_ID: %2.0f ", dID);
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// printf("Distance: %5.0f cm\n", (double)dist[TAG_ID]);
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// }
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// else
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// {
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// send[2] = ANCHOR_ID;
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// send[3] = TAG_ID;
|
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// memcpy(&send[4], &dist[TAG_ID], 2);
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// check = Checksum_u16(&send[2], 6);
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// memcpy(&send[8], &check, 2);
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// USART_puts(send, 10);
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// }
|
|
}
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}
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else
|
{
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/* Clear RX error events in the DW1000 status register. */
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dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_ALL_RX_ERR);
|
}
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}
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}
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else
|
{
|
/* Clear RX error events in the DW1000 status register. */
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dwt_write32bitreg(SYS_STATUS_ID, SYS_STATUS_ALL_RX_ERR);
|
}
|
}
|
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/*****************************************************************************************************************************************************
|
* NOTES:
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*
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* 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
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* 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.
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* - a response message sent by the responder allowing the initiator to go on with the process
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* - a final message sent by the initiator to complete the exchange and provide all information needed by the responder to compute the
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* time-of-flight (distance) estimate.
|
* The first 10 bytes of those frame are common and are composed of the following fields:
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* - byte 0/1: frame control (0x8841 to indicate a data frame using 16-bit addressing).
|
* - byte 2: sequence number, incremented for each new frame.
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* - byte 3/4: PAN TAG_ID (0xDECA).
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* - byte 5/6: destination address, see NOTE 3 below.
|
* - byte 7/8: source address, see NOTE 3 below.
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* - 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.
|
****************************************************************************************************************************************************/
|
