sl-uwb 82cc223fb8 feat: Add AT+PEER_RANGE= command for inter-anchor calibration (Issue #602)
- peer_range_once(): DS-TWR initiator role toward a peer anchor
  (POLL → RESP → FINAL, one-sided range estimate Ra - Da/2)
- AT+PEER_RANGE=<id>: returns +PEER_RANGE:<my>,<peer>,<mm>,<rssi>
  or +PEER_RANGE:ERR,<peer>,TIMEOUT

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-03-14 15:06:29 -04:00

543 lines
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/*
* uwb_anchor — SaltyBot ESP32 UWB Pro anchor firmware (TWR responder)
* Issue #544
*
* Hardware: Makerfabs ESP32 UWB Pro (DW3000 chip)
*
* Role
* ────
* Anchor sits on SaltyBot body, USB-connected to Jetson Orin.
* Two anchors per robot (anchor-0 port side, anchor-1 starboard).
* Person-worn tags initiate ranging; anchors respond.
*
* Protocol: Double-Sided TWR (DS-TWR)
* ────────────────────────────────────
* Tag → Anchor POLL (msg_type 0x01)
* Anchor → Tag RESP (msg_type 0x02, payload: T_poll_rx, T_resp_tx)
* Tag → Anchor FINAL (msg_type 0x03, payload: Ra, Da, Db timestamps)
* Anchor computes range via DS-TWR formula, emits +RANGE on Serial.
*
* Serial output (115200 8N1, USB-CDC to Jetson)
* ──────────────────────────────────────────────
* +RANGE:<anchor_id>,<range_mm>,<rssi_dbm>\r\n (on each successful range)
*
* AT commands (host → anchor)
* ───────────────────────────
* AT+RANGE? → returns last buffered +RANGE line
* AT+RANGE_ADDR=<hex_addr> → pair with specific tag (filter others)
* AT+RANGE_ADDR= → clear pairing (accept all tags)
* AT+ID? → returns +ID:<anchor_id>
* AT+PEER_RANGE=<id> → inter-anchor DS-TWR (for auto-calibration)
* → +PEER_RANGE:<my>,<peer>,<mm>,<rssi>
*
* Pin mapping — Makerfabs ESP32 UWB Pro
* ──────────────────────────────────────
* SPI SCK 18 SPI MISO 19 SPI MOSI 23
* DW CS 21 DW RST 27 DW IRQ 34
*
* Build
* ──────
* pio run -e anchor0 --target upload (port side)
* pio run -e anchor1 --target upload (starboard)
*/
#include <Arduino.h>
#include <SPI.h>
#include <math.h>
#include "dw3000.h" // Makerfabs MaUWB_DW3000 library
/* ── Configurable ───────────────────────────────────────────────── */
#ifndef ANCHOR_ID
# define ANCHOR_ID 0 /* 0 = port, 1 = starboard */
#endif
#define SERIAL_BAUD 115200
/* ── Pin map (Makerfabs ESP32 UWB Pro) ─────────────────────────── */
#define PIN_SCK 18
#define PIN_MISO 19
#define PIN_MOSI 23
#define PIN_CS 21
#define PIN_RST 27
#define PIN_IRQ 34
/* ── DW3000 channel / PHY config ───────────────────────────────── */
static dwt_config_t dw_cfg = {
5, /* channel 5 (6.5 GHz, best penetration) */
DWT_PLEN_128, /* preamble length */
DWT_PAC8, /* PAC size */
9, /* TX preamble code */
9, /* RX preamble code */
1, /* SFD type (IEEE 802.15.4z) */
DWT_BR_6M8, /* data rate 6.8 Mbps */
DWT_PHR_MODE_STD, /* standard PHR */
DWT_PHR_RATE_DATA,
(129 + 8 - 8), /* SFD timeout */
DWT_STS_MODE_OFF, /* STS off — standard TWR */
DWT_STS_LEN_64,
DWT_PDOA_M0, /* no PDoA */
};
/* ── Frame format ──────────────────────────────────────────────── */
/* Byte layout for all frames:
* [0] frame_type (FTYPE_*)
* [1] src_id (tag 8-bit addr, or ANCHOR_ID)
* [2] dst_id
* [3..] payload
* (FCS appended automatically by DW3000 — 2 bytes)
*/
#define FTYPE_POLL 0x01
#define FTYPE_RESP 0x02
#define FTYPE_FINAL 0x03
#define FRAME_HDR 3
#define FCS_LEN 2
/* RESP payload: T_poll_rx(5 B) + T_resp_tx(5 B) */
#define RESP_PAYLOAD 10
#define RESP_FRAME_LEN (FRAME_HDR + RESP_PAYLOAD + FCS_LEN)
/* FINAL payload: Ra(5 B) + Da(5 B) + Db(5 B) */
#define FINAL_PAYLOAD 15
#define FINAL_FRAME_LEN (FRAME_HDR + FINAL_PAYLOAD + FCS_LEN)
/* ── Timing ────────────────────────────────────────────────────── */
/* Turnaround delay: anchor waits 500 µs after poll_rx before tx_resp.
* DW3000 tick = 1/(128×499.2e6) ≈ 15.65 ps → 500 µs = ~31.95M ticks.
* Stored as uint32 shifted right 8 bits for dwt_setdelayedtrxtime. */
#define RESP_TX_DLY_US 500UL
#define DWT_TICKS_PER_US 63898UL /* 1µs in DW3000 ticks (×8 prescaler) */
#define RESP_TX_DLY_TICKS (RESP_TX_DLY_US * DWT_TICKS_PER_US)
/* How long anchor listens for FINAL after sending RESP */
#define FINAL_RX_TIMEOUT_US 3000
/* Speed of light (m/s) */
#define SPEED_OF_LIGHT 299702547.0
/* DW3000 40-bit timestamp mask */
#define DWT_TS_MASK 0xFFFFFFFFFFULL
/* Antenna delay (factory default; calibrate per unit for best accuracy) */
#define ANT_DELAY 16385
/* ── Interrupt flags (set in ISR, polled in main) ──────────────── */
static volatile bool g_rx_ok = false;
static volatile bool g_tx_done = false;
static volatile bool g_rx_err = false;
static volatile bool g_rx_to = false;
static uint8_t g_rx_buf[128];
static uint32_t g_rx_len = 0;
/* ── State ──────────────────────────────────────────────────────── */
/* Last successful range (serves AT+RANGE? queries) */
static int32_t g_last_range_mm = -1;
static char g_last_range_line[72] = {};
/* Optional tag pairing: 0 = accept all tags */
static uint8_t g_paired_tag_id = 0;
/* ── DW3000 ISR callbacks ───────────────────────────────────────── */
static void cb_tx_done(const dwt_cb_data_t *) { g_tx_done = true; }
static void cb_rx_ok(const dwt_cb_data_t *d) {
g_rx_len = d->datalength;
if (g_rx_len > sizeof(g_rx_buf)) g_rx_len = sizeof(g_rx_buf);
dwt_readrxdata(g_rx_buf, g_rx_len, 0);
g_rx_ok = true;
}
static void cb_rx_err(const dwt_cb_data_t *) { g_rx_err = true; }
static void cb_rx_to(const dwt_cb_data_t *) { g_rx_to = true; }
/* ── Timestamp helpers ──────────────────────────────────────────── */
static uint64_t ts_read(const uint8_t *p) {
uint64_t v = 0;
for (int i = 4; i >= 0; i--) v = (v << 8) | p[i];
return v;
}
static void ts_write(uint8_t *p, uint64_t v) {
for (int i = 0; i < 5; i++, v >>= 8) p[i] = (uint8_t)(v & 0xFF);
}
static inline uint64_t ts_diff(uint64_t later, uint64_t earlier) {
return (later - earlier) & DWT_TS_MASK;
}
static inline double ticks_to_s(uint64_t t) {
return (double)t / (128.0 * 499200000.0);
}
/* Estimate receive power from CIR diagnostics (dBm) */
static float rx_power_dbm(void) {
dwt_rxdiag_t d;
dwt_readdiagnostics(&d);
if (d.maxGrowthCIR == 0 || d.rxPreamCount == 0) return 0.0f;
float f = (float)d.maxGrowthCIR;
float n = (float)d.rxPreamCount;
return 10.0f * log10f((f * f) / (n * n)) - 121.74f;
}
/* ── Peer-anchor ranging (initiator role, for auto-calibration) ─── */
/* Timeout waiting for peer's RESP during inter-anchor ranging */
#define PEER_RX_RESP_TIMEOUT_US 3500
/* Block up to this many ms waiting for the interrupt flags */
#define PEER_WAIT_MS 20
/* Initiate a single DS-TWR exchange toward peer anchor `peer_id`.
* Returns range in mm (>=0) on success, or -1 on timeout/error.
* RSSI is stored in *rssi_out if non-null.
*
* Exchange:
* This anchor → peer POLL
* peer → This RESP (carries T_poll_rx, T_resp_tx)
* This anchor → peer FINAL (carries Ra, Da)
* This side computes its own range estimate from Ra/Da.
*/
static int32_t peer_range_once(uint8_t peer_id, float *rssi_out) {
/* ── Reset interrupt flags ── */
g_tx_done = g_rx_ok = g_rx_err = g_rx_to = false;
/* ── Build POLL frame ── */
uint8_t poll_buf[FRAME_HDR + FCS_LEN] = {
FTYPE_POLL,
(uint8_t)ANCHOR_ID,
peer_id,
};
dwt_writetxdata(sizeof(poll_buf), poll_buf, 0);
dwt_writetxfctrl(sizeof(poll_buf), 0, 1);
dwt_setrxtimeout(PEER_RX_RESP_TIMEOUT_US);
dwt_rxenable(DWT_START_RX_IMMEDIATE);
if (dwt_starttx(DWT_START_TX_IMMEDIATE | DWT_RESPONSE_EXPECTED) != DWT_SUCCESS)
return -1;
/* Wait for TX done */
uint32_t t0 = millis();
while (!g_tx_done && !g_rx_err && !g_rx_to) {
if (millis() - t0 > (uint32_t)PEER_WAIT_MS) return -1;
}
if (g_rx_err || g_rx_to) return -1;
g_tx_done = false;
/* Capture T_poll_tx */
uint64_t T_poll_tx;
dwt_readtxtimestamp((uint8_t *)&T_poll_tx);
T_poll_tx &= DWT_TS_MASK;
/* Wait for RESP */
t0 = millis();
while (!g_rx_ok && !g_rx_err && !g_rx_to) {
if (millis() - t0 > (uint32_t)PEER_WAIT_MS) return -1;
}
if (!g_rx_ok) return -1;
/* Validate RESP */
if (g_rx_len < (uint32_t)(FRAME_HDR + RESP_PAYLOAD + FCS_LEN)) return -1;
if (g_rx_buf[0] != FTYPE_RESP) return -1;
if (g_rx_buf[1] != peer_id) return -1;
if (g_rx_buf[2] != (uint8_t)ANCHOR_ID) return -1;
uint64_t T_resp_rx;
dwt_readrxtimestamp((uint8_t *)&T_resp_rx);
T_resp_rx &= DWT_TS_MASK;
/* Extract peer timestamps from RESP payload */
const uint8_t *pl = g_rx_buf + FRAME_HDR;
uint64_t T_poll_rx_peer = ts_read(pl);
uint64_t T_resp_tx_peer = ts_read(pl + 5);
/* DS-TWR Ra, Da */
uint64_t Ra = ts_diff(T_resp_rx, T_poll_tx);
uint64_t Da = ts_diff(T_resp_tx_peer, T_poll_rx_peer);
g_rx_ok = g_rx_err = g_rx_to = false;
/* ── Build FINAL frame ── */
uint8_t final_buf[FRAME_HDR + FINAL_PAYLOAD + FCS_LEN];
final_buf[0] = FTYPE_FINAL;
final_buf[1] = (uint8_t)ANCHOR_ID;
final_buf[2] = peer_id;
ts_write(final_buf + FRAME_HDR, Ra);
ts_write(final_buf + FRAME_HDR + 5, Da);
ts_write(final_buf + FRAME_HDR + 10, (uint64_t)0); /* Db placeholder */
dwt_setrxtimeout(0);
dwt_writetxdata(sizeof(final_buf), final_buf, 0);
dwt_writetxfctrl(sizeof(final_buf), 0, 1);
if (dwt_starttx(DWT_START_TX_IMMEDIATE) != DWT_SUCCESS) return -1;
t0 = millis();
while (!g_tx_done && !g_rx_err) {
if (millis() - t0 > (uint32_t)PEER_WAIT_MS) return -1;
}
g_tx_done = false;
/* Simplified one-sided range estimate: tof = Ra - Da/2 */
double tof_s = ticks_to_s(Ra) - ticks_to_s(Da) / 2.0;
if (tof_s < 0.0) tof_s = 0.0;
int32_t range_mm = (int32_t)(tof_s * SPEED_OF_LIGHT * 1000.0);
if (rssi_out) *rssi_out = rx_power_dbm();
/* Re-enable normal RX for tag ranging */
dwt_setrxtimeout(0);
dwt_rxenable(DWT_START_RX_IMMEDIATE);
return range_mm;
}
/* ── AT command handler ─────────────────────────────────────────── */
static char g_at_buf[64];
static int g_at_idx = 0;
static void at_dispatch(const char *cmd) {
if (strcmp(cmd, "AT+RANGE?") == 0) {
if (g_last_range_mm >= 0)
Serial.println(g_last_range_line);
else
Serial.println("+RANGE:NO_DATA");
} else if (strcmp(cmd, "AT+ID?") == 0) {
Serial.printf("+ID:%d\r\n", ANCHOR_ID);
} else if (strncmp(cmd, "AT+RANGE_ADDR=", 14) == 0) {
const char *v = cmd + 14;
if (*v == '\0') {
g_paired_tag_id = 0;
Serial.println("+OK:UNPAIRED");
} else {
g_paired_tag_id = (uint8_t)strtoul(v, nullptr, 0);
Serial.printf("+OK:PAIRED=0x%02X\r\n", g_paired_tag_id);
}
} else if (strncmp(cmd, "AT+PEER_RANGE=", 14) == 0) {
/* Inter-anchor ranging for calibration.
* Usage: AT+PEER_RANGE=<peer_anchor_id>
* Response: +PEER_RANGE:<my_id>,<peer_id>,<range_mm>,<rssi_dbm>
* or: +PEER_RANGE:ERR,<peer_id>,TIMEOUT
*/
uint8_t peer_id = (uint8_t)strtoul(cmd + 14, nullptr, 0);
float rssi = 0.0f;
int32_t mm = peer_range_once(peer_id, &rssi);
if (mm >= 0) {
Serial.printf("+PEER_RANGE:%d,%d,%ld,%.1f\r\n",
ANCHOR_ID, peer_id, mm, (double)rssi);
} else {
Serial.printf("+PEER_RANGE:ERR,%d,TIMEOUT\r\n", peer_id);
}
} else {
Serial.println("+ERR:UNKNOWN_CMD");
}
}
static void serial_poll(void) {
while (Serial.available()) {
char c = (char)Serial.read();
if (c == '\r') continue;
if (c == '\n') {
g_at_buf[g_at_idx] = '\0';
if (g_at_idx > 0) at_dispatch(g_at_buf);
g_at_idx = 0;
} else if (g_at_idx < (int)(sizeof(g_at_buf) - 1)) {
g_at_buf[g_at_idx++] = c;
}
}
}
/* ── DS-TWR anchor state machine ────────────────────────────────── */
/*
* DS-TWR responder (one shot):
* 1. Wait for POLL from tag
* 2. Delayed-TX RESP (carry T_poll_rx + scheduled T_resp_tx)
* 3. Wait for FINAL from tag (tag embeds Ra, Da, Db)
* 4. Compute: Rb = T_final_rx T_resp_tx
* tof = (Ra·Rb Da·Db) / (Ra+Rb+Da+Db)
* range_m = tof × c
* 5. Print +RANGE line
*/
static void twr_cycle(void) {
/* --- 1. Listen for POLL --- */
dwt_setrxtimeout(0);
dwt_rxenable(DWT_START_RX_IMMEDIATE);
g_rx_ok = g_rx_err = false;
uint32_t deadline = millis() + 2000;
while (!g_rx_ok && !g_rx_err) {
serial_poll();
if (millis() > deadline) {
/* restart RX if we've been stuck */
dwt_rxenable(DWT_START_RX_IMMEDIATE);
deadline = millis() + 2000;
}
yield();
}
if (!g_rx_ok || g_rx_len < FRAME_HDR) return;
/* validate POLL */
if (g_rx_buf[0] != FTYPE_POLL) return;
uint8_t tag_id = g_rx_buf[1];
if (g_paired_tag_id != 0 && tag_id != g_paired_tag_id) return;
/* --- 2. Record T_poll_rx --- */
uint8_t poll_rx_raw[5];
dwt_readrxtimestamp(poll_rx_raw);
uint64_t T_poll_rx = ts_read(poll_rx_raw);
/* Compute delayed TX time: poll_rx + turnaround, aligned to 512-tick grid */
uint64_t resp_tx_sched = (T_poll_rx + RESP_TX_DLY_TICKS) & ~0x1FFULL;
/* Build RESP frame */
uint8_t resp[RESP_FRAME_LEN];
resp[0] = FTYPE_RESP;
resp[1] = ANCHOR_ID;
resp[2] = tag_id;
ts_write(&resp[3], T_poll_rx); /* T_poll_rx (tag uses this) */
ts_write(&resp[8], resp_tx_sched); /* scheduled T_resp_tx */
dwt_writetxdata(RESP_FRAME_LEN - FCS_LEN, resp, 0);
dwt_writetxfctrl(RESP_FRAME_LEN, 0, 1 /*ranging*/);
dwt_setdelayedtrxtime((uint32_t)(resp_tx_sched >> 8));
/* Enable RX after TX to receive FINAL */
dwt_setrxaftertxdelay(300);
dwt_setrxtimeout(FINAL_RX_TIMEOUT_US);
/* Fire delayed TX */
g_tx_done = g_rx_ok = g_rx_err = g_rx_to = false;
if (dwt_starttx(DWT_START_TX_DELAYED | DWT_RESPONSE_EXPECTED) != DWT_SUCCESS) {
dwt_forcetrxoff();
return; /* TX window missed — try next cycle */
}
/* Wait for TX done (short wait, ISR fires fast) */
uint32_t t0 = millis();
while (!g_tx_done && millis() - t0 < 15) { yield(); }
/* Read actual T_resp_tx */
uint8_t resp_tx_raw[5];
dwt_readtxtimestamp(resp_tx_raw);
uint64_t T_resp_tx = ts_read(resp_tx_raw);
/* --- 3. Wait for FINAL --- */
t0 = millis();
while (!g_rx_ok && !g_rx_err && !g_rx_to && millis() - t0 < 60) {
serial_poll();
yield();
}
if (!g_rx_ok || g_rx_len < FRAME_HDR + FINAL_PAYLOAD) return;
if (g_rx_buf[0] != FTYPE_FINAL) return;
if (g_rx_buf[1] != tag_id) return;
/* Extract DS-TWR timestamps from FINAL payload */
uint64_t Ra = ts_read(&g_rx_buf[3]); /* tag: T_resp_rx T_poll_tx */
uint64_t Da = ts_read(&g_rx_buf[8]); /* tag: T_final_tx T_resp_rx */
/* g_rx_buf[13..17] = Db from tag (cross-check, unused here) */
/* T_final_rx */
uint8_t final_rx_raw[5];
dwt_readrxtimestamp(final_rx_raw);
uint64_t T_final_rx = ts_read(final_rx_raw);
/* --- 4. DS-TWR formula --- */
uint64_t Rb = ts_diff(T_final_rx, T_resp_tx); /* anchor round-trip */
uint64_t Db = ts_diff(T_resp_tx, T_poll_rx); /* anchor turnaround */
double ra = ticks_to_s(Ra), rb = ticks_to_s(Rb);
double da = ticks_to_s(Da), db = ticks_to_s(Db);
double denom = ra + rb + da + db;
if (denom < 1e-15) return;
double tof = (ra * rb - da * db) / denom;
double range_m = tof * SPEED_OF_LIGHT;
/* Validity window: 0.1 m 130 m */
if (range_m < 0.1 || range_m > 130.0) return;
int32_t range_mm = (int32_t)(range_m * 1000.0 + 0.5);
float rssi = rx_power_dbm();
/* --- 5. Emit +RANGE --- */
snprintf(g_last_range_line, sizeof(g_last_range_line),
"+RANGE:%d,%ld,%.1f", ANCHOR_ID, (long)range_mm, rssi);
g_last_range_mm = range_mm;
Serial.println(g_last_range_line);
}
/* ── Arduino setup ──────────────────────────────────────────────── */
void setup(void) {
Serial.begin(SERIAL_BAUD);
delay(300);
Serial.printf("\r\n[uwb_anchor] anchor_id=%d starting\r\n", ANCHOR_ID);
SPI.begin(PIN_SCK, PIN_MISO, PIN_MOSI, PIN_CS);
/* Hardware reset */
pinMode(PIN_RST, OUTPUT);
digitalWrite(PIN_RST, LOW);
delay(2);
pinMode(PIN_RST, INPUT_PULLUP);
delay(5);
/* DW3000 probe + init (Makerfabs MaUWB_DW3000 library) */
if (dwt_probe((struct dwt_probe_s *)&dw3000_probe_interf)) {
Serial.println("[uwb_anchor] FATAL: DW3000 probe failed — check SPI wiring");
for (;;) delay(1000);
}
if (dwt_initialise(DWT_DW_INIT) != DWT_SUCCESS) {
Serial.println("[uwb_anchor] FATAL: dwt_initialise failed");
for (;;) delay(1000);
}
if (dwt_configure(&dw_cfg) != DWT_SUCCESS) {
Serial.println("[uwb_anchor] FATAL: dwt_configure failed");
for (;;) delay(1000);
}
dwt_setrxantennadelay(ANT_DELAY);
dwt_settxantennadelay(ANT_DELAY);
dwt_settxpower(0x0E080222UL); /* max TX power for 120 m range */
dwt_setcallbacks(cb_tx_done, cb_rx_ok, cb_rx_to, cb_rx_err,
nullptr, nullptr, nullptr);
dwt_setinterrupt(
DWT_INT_TXFRS | DWT_INT_RFCG | DWT_INT_RFTO |
DWT_INT_RFSL | DWT_INT_SFDT | DWT_INT_ARFE | DWT_INT_CPERR,
0, DWT_ENABLE_INT_ONLY);
attachInterrupt(digitalPinToInterrupt(PIN_IRQ),
[]() { dwt_isr(); }, RISING);
Serial.printf("[uwb_anchor] DW3000 ready ch=%d 6.8Mbps id=%d\r\n",
dw_cfg.chan, ANCHOR_ID);
Serial.println("[uwb_anchor] Listening for tags...");
}
/* ── Arduino loop ───────────────────────────────────────────────── */
void loop(void) {
serial_poll();
twr_cycle();
}