Bool reverting value with no input

Projects General Guidance
1

Hi,

I've got some strange behaviour on my project where a boolean value is reverting back to an initial state with no input, but stranger still, this doesn't happen when a 'Serial.print(Val)' is called about the value in question.

Project is Arduino Mego Pro, High Altitude balloon tracker. Receives data over LoRa and displays on a LCD.

Inside my Setup code I have this:

//============================SD Card===========================//

  if (!sd.begin(13, SPI_FULL_SPEED)){
    SD_present = false;
    Serial.println(F("SD card not detected..."));
  }
  else{
    SD_present = true;
    SD_Header();
    Serial.println(F("SD OK"));
  }

The value SD_present lets me know if there is an SD card in the slot during boot up. This value is initialised as: bool SD_present; before setup.

Here is my setup;

void setup() {

  Setup_code();

  Serial.println(SD_present);
  Serial.println(F("Setup complete"));
}

This is the output on the serial monitor:

Setup Started..
MPU Started
Compass Started
LoRa radio init OK!
SD OK
1
Setup complete

The '1' is in reference to the SD_present. It accurate displays whether there is an SD card in the slot. No issues so far...

In my main loop, I detect a button push, and this will start or stop data logging to the SD card on each press.
The issue I've been having is that when I run the code, it returns a '1' for SD_present, then in the main loop it's as if SD_present has reverted back to false and the datalogging isn't happening because it thinks there is no SD card.

BUT.... if I include

 Serial.println(SD_present);

in the main loop, then SD_present doesn't revert back to false and the code runs perfectly.

Main loop code;

void loop() {

  if(digitalRead(46) && millis() - Lastbutton1 > 600){
    Lastbutton1 = millis();
    screen++;
    lcd.clear();
    if(screen >= 4) screen = 1;
  }

  if((millis() - DisplayFinT) >= 900 && first_packet){
    DisplayFinT = millis();
    
    if(screen == 1) Display1();
    if(screen == 2) Display2();
    if(screen == 3) Display3();

    //Serial.println(SD_present);   /// THIS STATEMENT MAKES IT RUN FLAWLESSLY
  }

  if(digitalRead(31) && millis() - Lastbutton2 > 1000){
    Lastbutton2 = millis();
    DisplayFinT = millis();

    lcd.clear();
    lcd.setCursor(0, 2);
    
    if(SD_present){
      if(!recording){
        lcd.print("SD Recording Started");
        Serial.println("SD Recording Started");
      }
      else{
        lcd.print("SD Recording Stopped");
        Serial.println("SD Recording Stopped");
      }
      recording = !recording;
    }
    else{
      lcd.print("No SD card detected");
    }
    delay(15);
  }

  GPS();
  LoRa();
  
} //End of main loop

Why would a 'Serial.print' make the code run with no issues?

SD_present is called in the setup then never assigned a value again. It is just checked in the main loop to see if it is there.

I'm very confused...! TIA

IMG_4415
IMG_44151719×1284 210 KB

2

Not clear from the code snippet you posted.
Mybe you are overwriting the variable with another ( a pointer, an array out of bounds... )?
Try adding a dummy variable before and after the definition of SD_present

P.S.
If you have an hardware debugger try setting a data breakpoint on the variable.

1 Like
3

Please post a full sketch that illustrates the problem instead of bits and pieces of code that have to be stitched together. As it is we are left guessing how variables are declared and what their scope is

2 Likes
4

I've cut this down a bit to reduce how much is pasted here, but the code below has the exact same bug as mentioned.

#include <Wire.h>
#include <QMC5883LCompass.h>
#include <NMEAGPS.h>
#include <LiquidCrystal_I2C.h>
#include <SPI.h>
#include <RH_RF95.h>
#include <SdFat.h>
#include <EEPROM.h>

#define gpsPort Serial1
#define RFM95_CS 53
#define RFM95_RST 2
#define RFM95_INT 3
#define RF95_FREQ 433.0

SdFat sd;
SdFile myFile;

const int MPU_Address = 0x68;   // I2C address of the MPU-6050
const int Mag_Address = 0x0D;   // I2C address of the MPU-6050
static NMEAGPS  gps;            
LiquidCrystal_I2C lcd(0x27,20,4);
RH_RF95 rf95(RFM95_CS, RFM95_INT);
QMC5883LCompass compass;        // Compass

int32_t Lat_GPS_raw, Long_GPS_raw, Last_packet, Lastbutton1, Lastbutton2, DisplayFinT;
bool first_packet = false, recording = false, SD_present, SD_display = false;
byte screen = 1, reply = 1;
char filename[16];


struct payload{
  uint32_t Secs_since_launch;
  float Lat;
  float Long;
  float GPS_Alt;
  float GPS_Speed;
  float VS;
  float Temp_in;
  float Temp_out;
  float V_batt;
  float Max_Alt;
  uint8_t SF;
};
payload Data;


void setup() {

  Setup_code();

  Serial.println(SD_present);
  Serial.println(F("Setup complete"));
}


void loop() {

  if(digitalRead(46) && millis() - Lastbutton1 > 600){
    Lastbutton1 = millis();
    screen++;
    lcd.clear();
    if(screen >= 4) screen = 1;
  }

  if((millis() - DisplayFinT) >= 900 && first_packet){
    DisplayFinT = millis();

    if(SD_display){
      lcd.clear();
      SD_display = false;
    } 
    
    if(screen == 1) Display1();

    //Serial.print(SD_present);
    //Serial.println(recording);
  }

  if(digitalRead(31) && millis() - Lastbutton2 > 1000){
    Lastbutton2 = millis();
    DisplayFinT = millis();

    lcd.clear();
    lcd.setCursor(0, 2);
    
    if(SD_present){
      if(!recording){
        lcd.print("SD Recording Started");
        //Serial.println("SD Recording Started");
      }
      else{
        lcd.print("SD Recording Stopped");
        //Serial.println("SD Recording Stopped");
      }
      recording = !recording;
    }
    else{
      lcd.print("No SD card detected");
    }
    delay(15);
    SD_display = true;
  }

  LoRa();
  
} //End of main loop

//Angle Calculation

float Angle_Calc(){
  
  static int16_t Accel_X_offset = -150, Accel_Y_offset = 50, Accel_Z_offset = -100;

  int counter = 0;

  I2C_Read(MPU_Address, 0x3B, 6);                            // I2C Reading function
  while (Wire.available() < 6){
    counter++;
    if (counter > 5) break;
  } 
  int16_t Accel_X = Wire.read()<<8 | Wire.read();
  int16_t Accel_Y = Wire.read()<<8 | Wire.read();
  int16_t Accel_Z = Wire.read()<<8 | Wire.read();


  if (Accel_Z > (32767 + Accel_Z_offset)){                   //Stops Accel_Z over flowing
      Accel_Z = 32767 + Accel_Z_offset;
  }

  Accel_X -= Accel_X_offset;
  Accel_Y -= Accel_Y_offset;
  Accel_Z -= Accel_Z_offset;  
    
  float AccelXg = float(Accel_X) / 16384.0;                         // converted to g
  float AccelYg = float(Accel_Y) / 16384.0;
  float AccelZg = float(Accel_Z) / 16384.0;

  //// Accelerometer angle calculations ////
  float Acc_Resultant = sqrt((AccelYg * AccelYg) + (AccelZg * AccelZg));
  if (Acc_Resultant == 0) Acc_Resultant = 0.001;
  if (AccelZg == 0) AccelZg = 0.001;
  float Acc_Angle_X = atan(AccelYg / AccelZg ) * 57.30;
  float Acc_Angle_Y = atan(-AccelXg / Acc_Resultant ) * 57.30; 

  float pitch_rads = Acc_Angle_Y / 57.3;
  float roll_rads  = Acc_Angle_X / -57.3;


  ////////////////// Get magnatometer data //////////////////
  compass.read();
  int Mag_X = compass.getX();
  int Mag_Y = compass.getY();
  int Mag_Z = compass.getZ();

  float y = Mag_X;
  float x = Mag_Y;
  float z = Mag_Z;
  
  float sinRoll = sin(roll_rads);
  float cosRoll = cos(roll_rads);
  float sinPitch = sin(pitch_rads);
  float cosPitch = cos(pitch_rads);

  float LHS = -x*cosPitch + y*sinPitch*sinRoll + z*sinPitch*cosRoll;
  float RHS = z*sinRoll - y*cosRoll;
  
  float bearing = atan2(-LHS, RHS) * 57.3;
  bearing += 90;
  if(bearing < 0) bearing += 360;

  return bearing;
  
}


void Display1(){

  //==================Heading Formula Calculation================//

  float Lat = Lat_GPS_raw / 10000000.0;
  float Long = Long_GPS_raw / 10000000.0;

  float Lat_int_target = Data.Lat * 10000000;
  float Long_int_target = Data.Long * 10000000;

  float teta1 = radians(Lat);
  float teta2 = radians(Data.Lat);
  float delta2 = radians(Data.Long-Long);

  float y = sin(delta2) * cos(teta2);
  float x = cos(teta1)*sin(teta2) - sin(teta1)*cos(teta2)*cos(delta2);
  float bearing2object = atan2(y,x);
  bearing2object = degrees(bearing2object);// radians to degrees
  bearing2object = ( ((int)bearing2object + 360) % 360 );

  float True_HDG = Angle_Calc() + 1;

  int bearing = bearing2object - True_HDG;

  bearing = ((bearing + 360) % 360);


  //=========Distance to target Calculation========================//
  
  float Lat_dist = abs(Lat_GPS_raw - Lat_int_target) * 0.0111111;
  float Long_scale = radians(Lat);
  float Long_dist = abs(Long_GPS_raw - Long_int_target) * sin(Long_scale) * 0.0111111;
  float Distance_calc = sqrt((Lat_dist * Lat_dist) + (Long_dist * Long_dist));

  float VS = Data.VS;
  float Alt = Data.GPS_Alt;


  //========Display================================================//

  //Lat/Long
  lcd.setCursor(1, 0);
  lcd.print(Data.Lat, 5);
  lcd.print(F("   "));
  lcd.println(Data.Long, 5);


  //Alt
  lcd.setCursor(0, 1);
  lcd.print(F("Alt "));
  if (Alt >= 10000){
    lcd.setCursor(4,1);
  } 
  if (Alt >= 1000 && Alt < 10000 || Alt <= -100){
    lcd.print(F(" "));
    lcd.setCursor(5,1); 
  } 
  if (Alt < 1000 && Alt >= 100 || Alt <= -10 && Alt > -100){
    lcd.print(F("  "));
    lcd.setCursor(6,1);
  } 
  if (Alt < 100 && Alt >= 10 || Alt < 0 && Alt > -10){
    lcd.print(F("   "));
    lcd.setCursor(7,1);
  } 
  if (Alt < 10 && Alt >= 0){
    lcd.print(F("    "));
    lcd.setCursor(8,1);
  }
  lcd.print((int)Alt);
  lcd.print(F("m"));


  //VS
  lcd.setCursor(11, 1);
  lcd.print(F("VS "));
  if (VS <= -10) lcd.setCursor(13, 1);
  else if (VS > -10 && VS < 0 || VS >= 10) lcd.setCursor(14, 1);
  else if( VS >= 0 && VS < 10){
    lcd.setCursor(14, 1);
    lcd.print(F(" "));
  }
  lcd.print(VS,1);
  lcd.write(byte(1));
  lcd.write(byte(2));


  //Distance
  lcd.setCursor(0, 2);
  lcd.print(F("Dist        ")); // Originally 8 spaces

  if(Distance_calc >= 100000){
    lcd.setCursor(6,2);
    lcd.print(Distance_calc / 1000,0);
    lcd.print(F("km "));
  }
  else if(Distance_calc > 20000){
    lcd.setCursor(7,2);
    lcd.print(Distance_calc / 1000,0);
    lcd.print(F("km "));
  }
  else if(Distance_calc >= 10000){
    lcd.setCursor(5,2);
    lcd.print(Distance_calc / 1000,1);
    lcd.print(F("km "));
  }
  else if(Distance_calc >= 1000){
    lcd.setCursor(6,2);
    lcd.print(Distance_calc / 1000,1);
    lcd.print(F("km "));
  }
  else if(Distance_calc >=100){
    lcd.setCursor(6,2);
    lcd.print((int)Distance_calc);
    lcd.print(F("m "));
  }
  else if(Distance_calc > 10){
    lcd.setCursor(7,2);
    lcd.print((int)Distance_calc);
    lcd.print(F("m "));
  }
  else{
    lcd.setCursor(8,2);
    lcd.print((int)Distance_calc);
    lcd.print(F("m "));
  }


  // Bearing
  lcd.setCursor(12, 2);
  lcd.print(F("Brg "));
  if (bearing < 100) lcd.print(F("0"));
  if (bearing < 10)  lcd.print(F("0"));
  lcd.print((int)bearing);
  lcd.write(byte(0));

  // Speed
  lcd.setCursor(0, 3);
  lcd.print(F("Spd   "));
  
  if( Data.GPS_Speed < 10){
    lcd.setCursor(6,3);
  }
  else if(Data.GPS_Speed >= 10 && Data.GPS_Speed < 100){
    lcd.setCursor(5,3);
  }
  else if(Data.GPS_Speed >= 100){
    lcd.setCursor(4,3);
  }
  lcd.print(Data.GPS_Speed,0);
  lcd.write(byte(1));
  lcd.write(byte(2));


  //Packet time
  lcd.setCursor(10, 3);
  lcd.print(F(" Pkt "));
  static char tBuf[20];
  long Value = (millis() - Last_packet) / 1000;
  
  if (Value < 3600){
    byte Seconds = Value % 60;
    byte minutes = (Value/60)%60;
    sprintf(tBuf,"%02um%02u",minutes, Seconds);
    lcd.print(tBuf);
  }
  else{
    byte minutes = (Value/60)%60;
    byte hours = (Value/3600)%24;
    sprintf(tBuf,"%02u:%02u", hours, minutes);
    lcd.print(tBuf);
  }

}
  



void LoRa(){

  if (rf95.available())
  {
    // Should be a message for us now   
    uint8_t buf[RH_RF95_MAX_MESSAGE_LEN];
    uint8_t len = sizeof(buf);
    
    if (rf95.recv((uint8_t*)&Data, &len))
    {
      first_packet = true;
      Last_packet = millis();


      // Send a reply
      rf95.waitPacketSent();
      rf95.send((uint8_t *)&reply, sizeof(reply));
      
  
    }
  }
}



void I2C_Read(int Address, int Register, int Bytes){              // Function to read I2C values
  
    Wire.beginTransmission(Address);
    Wire.write(Register);
    Wire.endTransmission();
    Wire.requestFrom(Address,Bytes);
    
}



void SD_Header(){


  int file_count = EEPROM.read(1);            // Read from EEPROM location 1
  if (file_count > 99 || file_count == 0){    // If number is 0 or more than 100 make it 1
    file_count = 1;
  }
  
  sprintf(filename, "File_%02d.csv", file_count);


  if (!myFile.open(filename, O_RDWR | O_CREAT | O_AT_END)) {}
  String header = "Time (S), Lat, Long, GPS_Alt (m), GPS_Speed (m/s), VS (m/s), Temp_in (C), Temp_out (C), Vbatt (V), SF";
  myFile.println(header);
  myFile.close();

  EEPROM.write(1, file_count + 1);       // Increment EEPROM value by 1
    
}


void Setup_code(){

  pinMode(4, INPUT);
  Wire.begin();
  Serial.begin(115200);
  //while(!Serial){}
  delay(500);
  Serial.println("Setup Started..");
  

  //======================MPU6050=====================//

  byte GFS_SEL = 8; // creates binary 0b00001000, this makes gyro sensitivity 500 degs/sec. 65.536 LSBs/deg/sec
// for 250degs/sec use 0.Would need to change comp. filter calcs too.

  // Valid at 22 degs C
  int16_t Gyro_X_offset = -157; 
  int16_t Gyro_Y_offset = 102; 
  int16_t Gyro_Z_offset = -210; 

  Wire.beginTransmission(MPU_Address);
  if(Wire.endTransmission() != 0){
    Serial.println("MPU failed");
  }
      //Fail_Test++; 


  Wire.beginTransmission(MPU_Address);
  Wire.write(0x6B), Wire.write(0x00); // sends 0's to PWR MNGMT register 0x68 resetting it. 
  Wire.endTransmission();
  Wire.beginTransmission(MPU_Address);
  Wire.write(0x1B), Wire.write(GFS_SEL); // 0x1B register sets gyro scale, 
  Wire.endTransmission();

  Serial.println("MPU Started");
  
  int16_t(Gyro_X_offset1) = float(-0.5) * float(Gyro_X_offset);
  int16_t(Gyro_Y_offset1) = float(-0.5) * float(Gyro_Y_offset);
  int16_t(Gyro_Z_offset1) = float(-0.5) * float(Gyro_Z_offset);

  byte Gyro_X_H = highByte(Gyro_X_offset1); byte Gyro_X_L = lowByte(Gyro_X_offset1);
  byte Gyro_Y_H = highByte(Gyro_Y_offset1); byte Gyro_Y_L = lowByte(Gyro_Y_offset1);
  byte Gyro_Z_H = highByte(Gyro_Z_offset1); byte Gyro_Z_L = lowByte(Gyro_Z_offset1);

  Wire.beginTransmission(MPU_Address);
  Wire.write(0x13), Wire.write(Gyro_X_H); // 0x13 register sets gyro_X offset, upper byte 
  Wire.endTransmission();
  Wire.beginTransmission(MPU_Address);
  Wire.write(0x14), Wire.write(Gyro_X_L); // 0x14 register sets gyro_X offset, lower byte
  Wire.endTransmission();

  Wire.beginTransmission(MPU_Address);
  Wire.write(0x15), Wire.write(Gyro_Y_H); // 0x15 register sets gyro_Y offset, upper byte 
  Wire.endTransmission();
  Wire.beginTransmission(MPU_Address);
  Wire.write(0x16), Wire.write(Gyro_Y_L); // 0x16 register sets gyro_Y offset, lower byte
  Wire.endTransmission();

  Wire.beginTransmission(MPU_Address);
  Wire.write(0x17), Wire.write(Gyro_Z_H); // 0x17 register sets gyro_Z offset, upper byte 
  Wire.endTransmission();
  Wire.beginTransmission(MPU_Address);
  Wire.write(0x18), Wire.write(Gyro_Z_L); // 0x18 register sets gyro_Z offset, lower byte
  Wire.endTransmission();
  delay(500);

  ////////////// Compass ////////////////////////////

  Serial.println("Compass Started");

  compass.init();
  //compass.setCalibration(-1690, 1190, -1703, 1191, -1687, 1458);
  compass.setCalibrationOffsets(-174.00, -195.00, -147.00);
  compass.setCalibrationScales(1.00, 1.04, 0.96);
  ///// CALIBRATION TEST DATA ////// 

  gpsPort.begin(38400);

  //========================LoRa Init==============================//
  pinMode(RFM95_RST, OUTPUT);
  digitalWrite(RFM95_RST, HIGH);

  
  // manual reset
  digitalWrite(RFM95_RST, LOW);
  delay(10);
  digitalWrite(RFM95_RST, HIGH);
  delay(10);

  while (!rf95.init()) {
    Serial.println("LoRa radio init failed");
    while (1);
  }
  Serial.println("LoRa radio init OK!");

  // Defaults after init are 433.0MHz, modulation GFSK_Rb250Fd250, +13dbM
  if (!rf95.setFrequency(RF95_FREQ)) {
    while (1);
  }
  //Serial.print("Set Freq to: "); Serial.println(RF95_FREQ);

  // Defaults after init are 434.0MHz, 13dBm, Bw = 125 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on

  // The default transmitter power is 13dBm, using PA_BOOST.
  // If you are using RFM95/96/97/98 modules which uses the PA_BOOST transmitter pin, then 
  // you can set transmitter powers from 5 to 23 dBm:
  rf95.setTxPower(14, false);
  rf95.setSpreadingFactor(12);
  rf95.setSignalBandwidth(62500);

  //============================SD Card===========================//

  if (!sd.begin(13, SPI_FULL_SPEED)){
    SD_present = false;
    Serial.println(F("SD card not detected..."));
  }
  else{
    SD_present = true;
    SD_Header();
    Serial.println(F("SD OK"));
  }

  
  //============================LCD init==========================//

  uint8_t degrees2[8] = {0x1c,0x14,0x1c,0x0,0x0,0x0,0x0,0x0};
  uint8_t m_s_1[8] = {0xa,0x15,0x15,0x11,0x0,0x1,0x2,0x4};
  uint8_t m_s_2[8] = {0x1,0x2,0x4,0xb,0x14,0x2,0x1,0x6};
  
  lcd.init();                      // initialize the lcd 
  lcd.createChar(0, degrees2);
  lcd.createChar(1, m_s_1);
  lcd.createChar(2, m_s_2);
  lcd.clear();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("      Setup OK ");
  lcd.setCursor(0, 2);
  lcd.print(" Waiting for Packets");

  
}
5

Are you using tabs?

If that is all one reduced sketch, just post it. S'lotta work you leave for all of us to do otherwise.

No need to worry about posting what you may consider as a large amount of code.

a7

6

You neglected to call the begin method for the serial port monitor, or I can't see where you did.

Trust me that failing to do can make almost anything happen. It can be baffling.

a7

7

What happens if you set SD_present to true when it's declared?

bool first_packet = false, recording = false, SD_present = true, SD_display = false;
8

Are you using tabs?

Yeah I stick most things in their own tab for ease of use.

9

That was in the setup code.

void Setup_code(){

  pinMode(4, INPUT);
  Wire.begin();
  Serial.begin(115200);
  //while(!Serial){}
  delay(500);
  Serial.println("Setup Started..");
10

I joined all pieces together, set SD_present to true ( even if I have no sd ) and everytime i pull pin 31 high I get 'SD recording started/stopped' so it seems working to me

P.S.
clearly I don't have the varius periferals connected ( mpu, gps... ) so not sure what happen with these

11

So this works, not sure why.

Also of interest, I found out by swapping over:

GPS();
LoRa();

So that LoRa is first also does the trick. Any thoughts why? This is a strange one.

12

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