MeshForge
Smart Factory Wireless Mesh

/* ESP32-C6 Zigbee sensor node — 58s deep sleep, 2s active window
   Publishes: temperature, humidity, CO2, energy_wh, motion event  */

#include "esp_zigbee_core.h"
#include "esp_sleep.h"
#include "scd41_driver.h"
#include "cs5490_driver.h"

#define SLEEP_DURATION_US   (58 * 1000 * 1000)
#define ZIGBEE_CHANNEL      15

typedef struct {
    int16_t  temp_cdC;        /* °C × 100  */
    uint16_t humidity_pc;     /* % × 100   */
    uint16_t co2_ppm;
    uint32_t energy_wh;       /* cumulative */
    uint8_t  motion;
    uint8_t  battery_pc;
} node_report_t;

void app_main(void) {
    /* Woke from deep sleep — collect and transmit in <2s */
    node_report_t report = {0};

    scd41_wake_and_read(&report.temp_cdC, &report.humidity_pc, &report.co2_ppm);
    cs5490_read_energy(&report.energy_wh);
    report.motion     = pir_read();
    report.battery_pc = adc_read_battery_pct();

    /* Join Zigbee network (already paired — fast rejoin <150ms) */
    esp_zb_init(&cfg);
    esp_zb_set_primary_network_channel_set(1 << ZIGBEE_CHANNEL);
    zigbee_transmit_report(&report);

    /* Schedule next UWB ranging if coordinator requests it */
    if (rtc_mem_read_uwb_flag()) {
        uwb_dw1000_range_and_report();
        rtc_mem_clear_uwb_flag();
    }

    /* Back to deep sleep — wake on timer OR motion PIR GPIO */
    esp_sleep_enable_timer_wakeup(SLEEP_DURATION_US);
    esp_sleep_enable_ext0_wakeup(GPIO_PIR_INT, 1);
    esp_deep_sleep_start();
}

/* Two-Way Ranging (TWR) with DW1000 UWB module via SPI
   Achieves <10cm RMS error in industrial metal-dense environment */

#define SPEED_OF_LIGHT  299702547.0    /* m/s in air */
#define DW_TIME_UNIT    (1.0/499200000/128)   /* ~15.65ps */

float uwb_measure_distance_m(uint8_t anchor_id) {
    uint64_t t_poll_tx, t_poll_rx,
              t_resp_tx, t_resp_rx,
              t_final_tx, t_final_rx;

    /* Phase 1: Tag sends POLL */
    dwt_writetxfctrl(12, 0, 1);
    dwt_starttx(DWT_START_TX_IMMEDIATE);
    t_poll_tx = dwt_readtxtimestamp();

    /* Phase 2: Wait for anchor RESPONSE (timeout 5ms) */
    if (!dwt_wait_rx(5000)) return -1.0f;
    t_resp_rx = dwt_readrxtimestamp();

    /* Phase 3: Tag sends FINAL */
    dwt_writetxdata(&final_msg, sizeof(final_msg), 0);
    dwt_starttx(DWT_START_TX_IMMEDIATE);
    t_final_tx = dwt_readtxtimestamp();

    /* Receive RESULT from anchor (contains its timestamps) */
    if (!dwt_wait_rx(5000)) return -1.0f;
    dwt_readrxdata(&result, sizeof(result), 0);
    t_poll_rx  = result.t_poll_rx;
    t_resp_tx  = result.t_resp_tx;
    t_final_rx = result.t_final_rx;

    /* Compute ToF using asymmetric double-sided TWR formula */
    double Ra = (double)(t_resp_rx - t_poll_tx);
    double Rb = (double)(t_final_rx - t_resp_tx);
    double Da = (double)(t_resp_tx  - t_poll_rx);
    double Db = (double)(t_final_tx - t_resp_rx);

    double tof_ticks = (Ra * Rb - Da * Db) / (Ra + Rb + Da + Db);
    return (float)(tof_ticks * DW_TIME_UNIT * SPEED_OF_LIGHT);
}