Build Me Device That Uses Wifi To Scan

#include <Arduino.h>
#include <WiFi.h>
#include <WiFiManager.h>
#include <esp_wifi.h>
#include <SPI.h>
#include <SD.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_ILI9341.h>
#include <Adafruit_BNO055.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_MAX17048.h>

// Handheld CSI environmental-sensing receiver for ESP32-C6.
// CSI is a measurement of received Wi-Fi channel change, not an object camera.

// Forward declarations
void csiCallback(void *, wifi_csi_info_t *info);
void enableCsi();
void drawStaticScreen();
void drawReadings();
void createLog();
void generateTraffic();
void updateImu();
void calibrateStep();
void updateMeasurement();
void handleButtons();

static constexpr int TFT_CS = 21;
static constexpr int TFT_DC = 10;
static constexpr int TFT_RST = 11;
static constexpr int TFT_BACKLIGHT = 1;
static constexpr int SD_CS = 3;
static constexpr int I2C_SDA = 23;
static constexpr int I2C_SCL = 22;
static constexpr int SCAN_BUTTON = 6;
static constexpr int CAL_BUTTON = 7;

Adafruit_ILI9341 tft(TFT_CS, TFT_DC, TFT_RST);
Adafruit_BNO055 bno(55, 0x28, &Wire);
Adafruit_MAX17048 gauge;
WiFiManager wifiManager;

volatile uint32_t csiSamples = 0;
volatile float latestAmplitude = 0.0f;
volatile int latestSubcarriers = 0;
float baselineAmplitude = 0.0f;
float disturbance = 0.0f;
float imuMotion = 0.0f;
bool calibrating = false;
bool sensing = true;
bool sdReady = false;
bool imuReady = false;
bool gaugeReady = false;
uint32_t calibrationStart = 0;
uint32_t calibrationCount = 0;
float calibrationSum = 0.0f;
uint32_t lastScreen = 0;
uint32_t lastTraffic = 0;
uint32_t lastLog = 0;
uint32_t lastButtons = 0;

void csiCallback(void *, wifi_csi_info_t *info) {
  if (info == nullptr || info->buf == nullptr || info->len < 2) return;
  const int8_t *iq = info->buf;
  uint32_t sum = 0;
  int pairs = info->len / 2;
  for (int i = 0; i < pairs; ++i) {
    int16_t iPart = iq[i * 2];
    int16_t qPart = iq[i * 2 + 1];
    sum += (uint32_t)(iPart * iPart + qPart * qPart);
  }
  latestAmplitude = sqrtf((float)sum / pairs);
  latestSubcarriers = pairs;
  csiSamples++;
}

void enableCsi() {
  wifi_csi_config_t config = {};
  config.lltf_en = true;
  config.htltf_en = true;
  config.stbc_htltf2_en = true;
  config.ltf_merge_en = true;
  config.channel_filter_en = true;
  config.manu_scale = false;
  config.shift = false;
  esp_wifi_set_csi_rx_cb(csiCallback, nullptr);
  esp_wifi_set_csi_config(&config);
  esp_wifi_set_csi(true);
}

void drawStaticScreen() {
  tft.fillScreen(ILI9341_BLACK);
  tft.setTextWrap(false);
  tft.setTextSize(2);
  tft.setTextColor(ILI9341_CYAN);
  tft.setCursor(12, 10);
  tft.print("CSI ENVIRONMENT");
  tft.drawFastHLine(10, 34, 220, ILI9341_DARKCYAN);
  tft.setTextSize(1);
  tft.setTextColor(ILI9341_LIGHTGREY);
  tft.setCursor(12, 215);
  tft.print("SCAN: start/stop logging");
  tft.setCursor(12, 228);
  tft.print("CAL: hold still, set baseline");
}

void drawReadings() {
  tft.fillRect(10, 45, 220, 158, ILI9341_BLACK);
  tft.setTextSize(2);
  tft.setTextColor(WiFi.status() == WL_CONNECTED ? ILI9341_GREEN : ILI9341_RED);
  tft.setCursor(12, 48);
  tft.print(WiFi.status() == WL_CONNECTED ? "Wi-Fi linked" : "Wi-Fi offline");

  tft.setTextColor(ILI9341_WHITE);
  tft.setCursor(12, 76);
  tft.printf("CSI: %lu", (unsigned long)csiSamples);
  tft.setCursor(12, 100);
  tft.printf("Bins: %d", latestSubcarriers);
  tft.setCursor(12, 124);
  tft.printf("Change: %.1f%%", disturbance);

  uint16_t color = disturbance > 18.0f ? ILI9341_RED : (disturbance > 7.0f ? ILI9341_YELLOW : ILI9341_GREEN);
  tft.setTextColor(color);
  tft.setCursor(12, 150);
  if (!sensing) tft.print("PAUSED");
  else if (disturbance > 18.0f && imuMotion < 1.2f) tft.print("POSSIBLE PRESENCE");
  else if (disturbance > 7.0f) tft.print("RF DISTURBANCE");
  else tft.print("ENVIRONMENT QUIET");

  tft.setTextSize(1);
  tft.setTextColor(ILI9341_LIGHTGREY);
  tft.setCursor(12, 181);
  float percent = gaugeReady ? gauge.cellPercent() : -1.0f;
  if (percent >= 0) tft.printf("Battery %.0f%%  IMU %.2f", percent, imuMotion);
  else tft.printf("IMU %.2f", imuMotion);
  tft.setCursor(12, 194);
  tft.print(sdReady ? "microSD logging ready" : "microSD not found");
}

void createLog() {
  if (!sdReady || SD.exists("/csi.csv")) return;
  File log = SD.open("/csi.csv", FILE_WRITE);
  if (log) {
    log.println("ms,csi_samples,mean_iq_amplitude,baseline,disturbance_percent,imu_motion");
    log.close();
  }
}

void generateTraffic() {
  if (WiFi.status() != WL_CONNECTED) return;
  WiFiClient client;
  IPAddress gateway = WiFi.gatewayIP();
  if (gateway[0] == 0) return;
  // A short HTTP request encourages a response packet from the selected AP/router.
  // CSI is also captured from ordinary received Wi-Fi traffic.
  if (client.connect(gateway, 80)) {
    client.print("HEAD / HTTP/1.0\r\nHost: router\r\nConnection: close\r\n\r\n");
    delay(8);
    while (client.available()) client.read();
    client.stop();
  }
}

void updateImu() {
  if (!imuReady) return;
  sensors_event_t event;
  bno.getEvent(&event, Adafruit_BNO055::VECTOR_GYROSCOPE);
  float gyro = fabs(event.gyro.x) + fabs(event.gyro.y) + fabs(event.gyro.z);
  imuMotion = gyro;
}

void calibrateStep() {
  if (!calibrating) return;
  calibrationSum += latestAmplitude;
  calibrationCount++;
  if (millis() - calibrationStart >= 5000) {
    if (calibrationCount > 5) baselineAmplitude = calibrationSum / calibrationCount;
    calibrating = false;
    drawStaticScreen();
  }
}

void updateMeasurement() {
  if (baselineAmplitude <= 0.5f) baselineAmplitude = latestAmplitude;
  if (baselineAmplitude > 0.5f) {
    disturbance = fabs(latestAmplitude - baselineAmplitude) * 100.0f / baselineAmplitude;
  }
  if (sensing && !calibrating && sdReady && millis() - lastLog > 1000) {
    lastLog = millis();
    File log = SD.open("/csi.csv", FILE_APPEND);
    if (log) {
      log.printf("%lu,%lu,%.3f,%.3f,%.2f,%.3f\n", (unsigned long)millis(), (unsigned long)csiSamples, latestAmplitude, baselineAmplitude, disturbance, imuMotion);
      log.close();
    }
  }
}

void handleButtons() {
  if (millis() - lastButtons < 180) return;
  if (digitalRead(SCAN_BUTTON) == LOW) {
    sensing = !sensing;
    lastButtons = millis();
  }
  if (digitalRead(CAL_BUTTON) == LOW) {
    calibrating = true;
    calibrationStart = millis();
    calibrationCount = 0;
    calibrationSum = 0;
    lastButtons = millis();
  }
}

void setup() {
  pinMode(TFT_BACKLIGHT, OUTPUT);
  digitalWrite(TFT_BACKLIGHT, HIGH);
  pinMode(SCAN_BUTTON, INPUT_PULLUP);
  pinMode(CAL_BUTTON, INPUT_PULLUP);
  Serial.begin(115200);
  Wire.begin(I2C_SDA, I2C_SCL);
  SPI.begin(18, 19, 20);

  tft.begin();
  tft.setRotation(1);
  drawStaticScreen();
  tft.setTextSize(1);
  tft.setTextColor(ILI9341_WHITE);
  tft.setCursor(12, 45);
  tft.print("Starting sensors...");

  imuReady = bno.begin();
  if (imuReady) bno.setExtCrystalUse(true);
  gaugeReady = gauge.begin();
  sdReady = SD.begin(SD_CS, SPI, 8000000);
  createLog();

  wifiManager.setConfigPortalTimeout(180);
  tft.setCursor(12, 60);
  tft.print("Choose router in setup page");
  bool linked = wifiManager.autoConnect("CSI-Radar-Setup", "csi-radar-setup");
  if (linked) enableCsi();
  drawStaticScreen();
}

void loop() {
  handleButtons();
  if (WiFi.status() == WL_CONNECTED && millis() - lastTraffic > 650) {
    lastTraffic = millis();
    generateTraffic();
  }
  updateImu();
  calibrateStep();
  updateMeasurement();
  if (millis() - lastScreen > 300) {
    lastScreen = millis();
    drawReadings();
  }
}