Ground Station Code

/*
   GROUND STATION: ALL-DATA + VOLTAGE FIX
   - Fixed: GS Battery now reads correctly from Pin A0.
   - Top:   Signal | Rocket Volts | Rocket %
   - Line2: Rocket Charge Time Est.
   - Bot:   Status | Ground Station Volts | Ground Station %
   - Logs:  "flight.csv" (Persistent)
*/

#include <Arduino.h>
#include <SPI.h>
#include <Wire.h>
#include <RadioLib.h>
#include <U8g2lib.h>
#include <Adafruit_LittleFS.h>
#include <InternalFileSystem.h>

using namespace Adafruit_LittleFS_Namespace;

// --- PINS (XIAO nRF52840) ---
const int PIN_LORA_SCK  = 30; 
const int PIN_LORA_MISO = 3;  
const int PIN_LORA_MOSI = 28; 
const int PIN_LORA_CS   = 46; 
const int PIN_LORA_DIO1 = 7;  
const int PIN_LORA_RST  = 39; 
const int PIN_LORA_BUSY = 42; 

const int PIN_OLED_SCL  = 5;  
const int PIN_OLED_SDA  = 6;  
const int PIN_BUZZER    = 32; 

// --- BATTERY FIX: Use A0 for Expansion Board ---
const int PIN_GS_BAT_READ = A0; 

// Display Driver
U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE, PIN_OLED_SCL, PIN_OLED_SDA);

SX1262 radio = new Module(PIN_LORA_CS, PIN_LORA_DIO1, PIN_LORA_RST, PIN_LORA_BUSY);

// Logic Variables
bool hasAlerted = false;
float startAlt = -1000.0; 
bool isAscending = false;

// --- HELPER: Read Ground Station Battery (FIXED) ---
float readGSBattery() {
  // The Expansion board has a simple voltage divider on A0
  // No enable pin needed.
  int val = analogRead(PIN_GS_BAT_READ);
  
  // Math: (ADC / 1023) * 3.3V_Ref * Divider_Correction
  // The expansion board usually uses a 1/2 divider, so we multiply by ~1.51 to 2.0
  // We use 1.51 multiplier for XIAO logic (experimentally tuned for nRF52)
  float voltage = (val / 1023.0) * 3.3 * 1.51; 
  
  // If reading is too low (USB powered only), clamp it
  if (voltage < 0.1) return 0.0;
  
  // Correction: If it reads low (like 2.4V) when full, change 1.51 to 2.0
  // Try 2.0 first if it's a standard divider
  return (val / 1023.0) * 3.3 * 2.0; 
}

// --- HELPER: Map Float to % ---
int getPercent(float volts) {
  int pct = map((long)(volts * 100), 360, 420, 0, 100);
  return constrain(pct, 0, 100);
}

// --- HELPER: Estimate Charge Time ---
String getChargeTime(float volts) {
  if (volts >= 4.15) return "Full";
  float voltageNeeded = 4.20 - volts;
  float hoursLeft = voltageNeeded * 10.0; 
  return "~" + String(hoursLeft, 1) + "h";
}

void setup() {
  Serial.begin(115200);
  pinMode(PIN_BUZZER, OUTPUT);
  digitalWrite(PIN_BUZZER, LOW);
  
  // FIX: Expansion board uses A0
  pinMode(PIN_GS_BAT_READ, INPUT);
  analogReadResolution(10); 

  // 1. ROBUST FILESYSTEM
  if (!InternalFS.begin()) {
    InternalFS.format(); 
    InternalFS.begin();
  }
  
  // Persistent Log Header
  File f = InternalFS.open("/flight.csv", FILE_O_WRITE);
  if(f) { 
    f.seek(f.size()); 
    f.println(); f.println("--- RESTART ---"); 
    if (f.size() < 20) f.println("TimeMS,Callsign,Lat,Lon,Alt,Speed,Volts,Pop");
    f.close(); 
  }

  // 2. Init Screen
  Wire.setPins(PIN_OLED_SDA, PIN_OLED_SCL);
  u8g2.setI2CAddress(0x3D * 2);             
  u8g2.begin();
  
  // 3. Init Radio
  SPI.setPins(PIN_LORA_MISO, PIN_LORA_SCK, PIN_LORA_MOSI);
  SPI.begin();
  radio.begin(915.0);
  radio.setSpreadingFactor(10); radio.setBandwidth(250.0); radio.setCodingRate(7); radio.setOutputPower(22);      
}

void loop() {
  if(Serial.available()) {
     String cmd = Serial.readStringUntil('\n');
     if(cmd.indexOf("dump") >= 0) {
        Serial.println("\n--- DUMP ---");
        File f = InternalFS.open("/flight.csv", FILE_O_READ);
        if(f) { while(f.available()) Serial.write(f.read()); f.close(); }
        Serial.println("\n--- END ---");
     }
  }

  String str;
  int state = radio.receive(str);

 // Insert your callsign, then delete this comment  if (state == RADIOLIB_ERR_NONE && str.indexOf("Your_Callsign_Here") >= 0) {
     Serial.println(str);
     
     // Log
     File f = InternalFS.open("/flight.csv", FILE_O_WRITE);
     if(f) { f.seek(f.size()); f.println(String(millis()) + "," + str); f.close(); }

     bool dropDetected = str.endsWith(",1");

     // --- ALARM ---
     if (dropDetected && !hasAlerted) {
         u8g2.clearBuffer();
         u8g2.setFont(u8g2_font_helvB10_tr); u8g2.drawStr(0, 25, "Chute Deployment!");
         u8g2.setFont(u8g2_font_ncenB08_tr); u8g2.drawStr(0, 45, "Continuity Break!");
         u8g2.sendBuffer();
         unsigned long s = millis();
         while(millis() - s < 3000) { tone(PIN_BUZZER, 4000); delay(200); noTone(PIN_BUZZER); delay(100); }
         hasAlerted = true;
     }
     if (!dropDetected) hasAlerted = false;

     // --- PARSING ---
     int c1 = str.indexOf(',');
     int c2 = str.indexOf(',', c1+1);
     int c3 = str.indexOf(',', c2+1);
     int c4 = str.indexOf(',', c3+1);
     int c5 = str.indexOf(',', c4+1); 
     int c6 = str.indexOf(',', c5+1); 
     
     String coords = str.substring(c1+1, c3);
     String altStr = str.substring(c3+1, c4);
     String spd = str.substring(c4+1, c5);
     float rktVolts = str.substring(c5+1, c6).toFloat();
     
     float currentAlt = altStr.toFloat();
     if (startAlt == -1000.0 && currentAlt > 0) startAlt = currentAlt; 
     if (startAlt != -1000.0 && currentAlt > (startAlt + 50)) isAscending = true;

     // --- DISPLAY UPDATE ---
     float gsVolts = readGSBattery();

     u8g2.clearBuffer();
     u8g2.setFont(u8g2_font_5x8_tr); 
     
     // LINE 1: Signal | Rkt Volts | Rkt %
     u8g2.setCursor(0, 8);
     u8g2.print("S:"); u8g2.print(radio.getRSSI());
     u8g2.print(" R:"); u8g2.print(rktVolts, 1); u8g2.print("V");
     u8g2.print(" "); u8g2.print(getPercent(rktVolts)); u8g2.print("%");
     
     // LINE 2: Charge Time Est
     u8g2.setCursor(0, 18); 
     u8g2.print("R-Chg: "); u8g2.print(getChargeTime(rktVolts));

     // LINE 3: Coords
     u8g2.setCursor(0, 28); u8g2.print(coords);
     
     // LINE 4: BIG DATA
     u8g2.setFont(u8g2_font_ncenB10_tr); 
     u8g2.setCursor(0, 44);
     u8g2.print(altStr); u8g2.print("ft "); 
     u8g2.print(spd); u8g2.print("mh");

     // LINE 5: Status | GS Info
     u8g2.setFont(u8g2_font_5x8_tr); 
     u8g2.setCursor(0, 58);
     if(hasAlerted) u8g2.print("DESCENDING");
     else if (isAscending) u8g2.print("ASCENDING ");
     else u8g2.print("READY       ");
     
     // GS Info (Bottom Right)
     u8g2.setCursor(65, 58);
     u8g2.print("G:"); u8g2.print(gsVolts, 1); u8g2.print("V ");
     u8g2.print(getPercent(gsVolts)); u8g2.print("%");
     
     u8g2.sendBuffer();
  }
}