MPU6050 values constantly at 0/-0

Other Hardware Sensors
1

Using an MPU6050 with an ESP8266 nodemcu for a wearable fall-detection device but the output values will only display 0 or -0 for the six axes and the temperature will also not change in value.

Here is the code that I used:
#include <Wire.h>

// MPU6050 Slave Device Address
const uint8_t MPU6050SlaveAddress = 0x68;

// Select SDA and SCL pins for I2C communication
const uint8_t SCL_PIN = D6;
const uint8_t SDA_PIN = D7;

// sensitivity scale factor respective to full scale setting provided in datasheet
const uint16_t AccelScaleFactor = 16384;
const uint16_t GyroScaleFactor = 131;

// MPU6050 few configuration register addresses
const uint8_t MPU6050_REGISTER_SMPLRT_DIV = 0x19;
const uint8_t MPU6050_REGISTER_USER_CTRL = 0x6A;
const uint8_t MPU6050_REGISTER_PWR_MGMT_1 = 0x6B;
const uint8_t MPU6050_REGISTER_PWR_MGMT_2 = 0x6C;
const uint8_t MPU6050_REGISTER_CONFIG = 0x1A;
const uint8_t MPU6050_REGISTER_GYRO_CONFIG = 0x1B;
const uint8_t MPU6050_REGISTER_ACCEL_CONFIG = 0x1C;
const uint8_t MPU6050_REGISTER_FIFO_EN = 0x23;
const uint8_t MPU6050_REGISTER_INT_ENABLE = 0x38;
const uint8_t MPU6050_REGISTER_ACCEL_XOUT_H = 0x3B;
const uint8_t MPU6050_REGISTER_SIGNAL_PATH_RESET = 0x69;

int16_t AccelX, AccelY, AccelZ, Temperature, GyroX, GyroY, GyroZ;

void setup() {
Serial.begin(19200);
Wire.begin(SDA, SCL);
Wire.write(0x6B);
Wire.write(0);
MPU6050_Init();
}

void loop() {
double Ax, Ay, Az, T, Gx, Gy, Gz;
Wire.endTransmission(false);

Read_RawValue(MPU6050SlaveAddress, MPU6050_REGISTER_ACCEL_XOUT_H);

//divide each with their sensitivity scale factor
Ax = (double)AccelX/AccelScaleFactor;
Ay = (double)AccelY/AccelScaleFactor;
Az = (double)AccelZ/AccelScaleFactor;
T = (double)Temperature/340+36.53; //temperature formula
Gx = (double)GyroX/GyroScaleFactor;
Gy = (double)GyroY/GyroScaleFactor;
Gz = (double)GyroZ/GyroScaleFactor;

Serial.print("Ax: "); Serial.print(Ax);
Serial.print(" Ay: "); Serial.print(Ay);
Serial.print(" Az: "); Serial.print(Az);
Serial.print(" T: "); Serial.print(T);
Serial.print(" Gx: "); Serial.print(Gx);
Serial.print(" Gy: "); Serial.print(Gy);
Serial.print(" Gz: "); Serial.println(Gz);

delay(50);
}

void I2C_Write(uint8_t deviceAddress, uint8_t regAddress, uint8_t data){
Wire.beginTransmission(deviceAddress);
Wire.write(regAddress);
Wire.write(data);
Wire.endTransmission();
}

// read all 14 register
void Read_RawValue(uint8_t deviceAddress, uint8_t regAddress){
Wire.beginTransmission(deviceAddress);
Wire.write(regAddress);
Wire.endTransmission();
Wire.requestFrom(deviceAddress, (uint8_t)14);
AccelX = (((int16_t)Wire.read()<<8) | Wire.read());
AccelY = (((int16_t)Wire.read()<<8) | Wire.read());
AccelZ = (((int16_t)Wire.read()<<8) | Wire.read());
Temperature = (((int16_t)Wire.read()<<8) | Wire.read());
GyroX = (((int16_t)Wire.read()<<8) | Wire.read());
GyroY = (((int16_t)Wire.read()<<8) | Wire.read());
GyroZ = (((int16_t)Wire.read()<<8) | Wire.read());
}

//configure MPU6050
void MPU6050_Init(){
delay(150);
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_SMPLRT_DIV, 0x07);
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_PWR_MGMT_1, 0x00 );
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_PWR_MGMT_2, 0x00);
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_CONFIG, 0x00);
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_GYRO_CONFIG, 0x00);//set +/- 250 degree/second full scale
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_ACCEL_CONFIG, 0x00);// set +/- 2g full scale
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_FIFO_EN, 0x00);
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_INT_ENABLE, 0x01);
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_SIGNAL_PATH_RESET, 0x00);
I2C_Write(MPU6050SlaveAddress, MPU6050_REGISTER_USER_CTRL, 0x00);
}

The attached images are the results of the serial monitor. I'm not sure if there's anything wrong with the code or if it is a hardware problem? I'm positive the circuit is correct. Any corrections or suggestions would be much appreciated.

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2

Have you ran an I2C scanner to confirm the device I2C address and that the device is communication via the I2C bus?

// I2C scanner by Nick Gammon.  Thanks Nick.

#include <Wire.h>

void setup() {
  Serial.begin (115200); //*****  make sure serial monitor baud matches *****

  // Leonardo: wait for serial port to connect
  while (!Serial) 
    {
    }

  Serial.println ();
  Serial.println ("I2C scanner. Scanning ...");
  byte count = 0;
  
  Wire.begin();
  for (byte i = 1; i < 120; i++)
  {
    Wire.beginTransmission (i);
    if (Wire.endTransmission () == 0)
      {
      Serial.print ("Found address: ");
      Serial.print (i, DEC);
      Serial.print (" (0x");
      Serial.print (i, HEX);
      Serial.println (")");
      count++;
      delay (1);  // maybe unneeded?
      } // end of good response
  } // end of for loop
  Serial.println ("Done.");
  Serial.print ("Found ");
  Serial.print (count, DEC);
  Serial.println (" device(s).");
}  // end of setup

void loop() {}
3

You are not waking up the MPU in Setup(). (no begin and no end transmission)

Wire.beginTransmission(MPU_addr);
Wire.write(0x6B); // PWR_MGMT_1 register
Wire.write(0); // set to zero (wakes up the MPU-6050)
Wire.endTransmission(true);

In loop() you are missing out as well

Wire.beginTransmission(MPU_addr);
Wire.write(0x3B); // starting with register 0x3B (ACCEL_XOUT_H)
Wire.endTransmission(false);

And actually before reading you should check there is data available , but I expect not the cause of the issue
regards,
Paul

4

@OP

You may try the following sketch in your ESP-MPU setup only for Temperature measurement. It works for my case. My MPu's I2C address is 0x69. The ESP's I2C Bus: Wire.begin(4, 5); //SDA, SCL.

#include <Wire.h>
#include <MPU6050.h>
#define MPU_ADDRESS 0x69  //in my Library the address is coded as 0x69

MPU6050 mpu;   //device address 0x69 keyed in Librart AD0=LH

void setup()
{
  Wire.begin(4, 5); //SDA, SCL = D2, D1
  Serial.begin(115200);//9600);
  Serial.println("Initialize MPU6050");
  Serial1.begin(115200);//9600);

  while (!mpu.begin(MPU6050_SCALE_2000DPS, MPU6050_RANGE_2G))
  {
    Serial.println("Could not find a valid MPU6050 sensor, check wiring!");
    delay(1000);
  }
}

void loop()
{
  float temp = mpu.readTemperature();

  Serial.print(" Temp = ");
  Serial.print(temp, 2);
  Serial.println(" *C");
  //-------------------------
  
  delay(1000);
}

sm38.png

sm38.png