Adafruit MPU-6050 and adafruit I2C Multiplexer

Question

I have 3 adafruit MPUs hooked up to adafruit I2c Multiplexer. All of which is hooked up to a Arduino uno. Attached is also my code.

/* Assign a unique ID to this sensor at the same time */

/*Adafruit_HMC5883_Unified mpu1 = Adafruit_HMC5883_Unified(1);
Adafruit_HMC5883_Unified mpu2 = Adafruit_HMC5883_Unified(2);*/

#define TCAADDR 0x70

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
Adafruit_MPU6050 mpu1 = Adafruit_MPU6050();
Adafruit_MPU6050 mpu2 = Adafruit_MPU6050();
Adafruit_MPU6050 mpu3 = Adafruit_MPU6050();

void displaySensorDetails(Adafruit_MPU6050 *mpu)
{
sensor_t sensor;
mpu->getGyroSensor();
Serial.println("------------------------------------");
Serial.print ("Sensor: "); Serial.println(sensor.name);
Serial.print ("Driver Ver: "); Serial.println(sensor.version);
Serial.print ("Unique ID: "); Serial.println(sensor.sensor_id);
Serial.print ("Max Value: "); Serial.print(sensor.max_value); Serial.println(" uT");
Serial.print ("Min Value: "); Serial.print(sensor.min_value); Serial.println(" uT");
Serial.print ("Resolution: "); Serial.print(sensor.resolution); Serial.println(" uT");
Serial.println("------------------------------------");
Serial.println("");
delay(500);
}

void setUpMPU(Adafruit_MPU6050 *mpu)
{
  mpu->setAccelerometerRange(MPU6050_RANGE_8_G);
  Serial.print("Accelerometer range set to: ");
  switch (mpu->getAccelerometerRange()) {
  case MPU6050_RANGE_2_G:
    Serial.println("+-2G");
    break;
  case MPU6050_RANGE_4_G:
    Serial.println("+-4G");
    break;
  case MPU6050_RANGE_8_G:
    Serial.println("+-8G");
    break;
  case MPU6050_RANGE_16_G:
    Serial.println("+-16G");
    break;
  }
  mpu->setGyroRange(MPU6050_RANGE_500_DEG);
  Serial.print("Gyro range set to: ");
  switch (mpu->getGyroRange()) {
  case MPU6050_RANGE_250_DEG:
    Serial.println("+- 250 deg/s");
    break;
  case MPU6050_RANGE_500_DEG:
    Serial.println("+- 500 deg/s");
    break;
  case MPU6050_RANGE_1000_DEG:
    Serial.println("+- 1000 deg/s");
    break;
  case MPU6050_RANGE_2000_DEG:
    Serial.println("+- 2000 deg/s");
    break;
  }
  
  mpu->setFilterBandwidth(MPU6050_BAND_21_HZ);
  Serial.print("Filter bandwidth set to: ");
  switch (mpu->getFilterBandwidth()) {
  case MPU6050_BAND_260_HZ:
    Serial.println("260 Hz");
    break;
  case MPU6050_BAND_184_HZ:
    Serial.println("184 Hz");
    break;
  case MPU6050_BAND_94_HZ:
    Serial.println("94 Hz");
    break;
  case MPU6050_BAND_44_HZ:
    Serial.println("44 Hz");
    break;
  case MPU6050_BAND_21_HZ:
    Serial.println("21 Hz");
    break;
  case MPU6050_BAND_10_HZ:
    Serial.println("10 Hz");
    break;
  case MPU6050_BAND_5_HZ:
    Serial.println("5 Hz");
    break;
} 
}

void tcaselect(uint8_t i) {
if (i > 7) return;
Wire.beginTransmission(TCAADDR);
Wire.write(1 << i);
Wire.endTransmission();
}

void setup(void)
{
while (!Serial)
    delay(10); // will pause Zero, Leonardo, etc until serial console opens
Serial.begin(115200);
Serial.println("HMC5883 Magnetometer Test"); Serial.println("");
Serial.println("HMC5883 Magnetometer Test"); Serial.println("");

/* Initialise the 1st sensor */
tcaselect(0);
mpu1.setAccelerometerRange(MPU6050_RANGE_8_G);
Serial.print("Accelerometer range set to: ");
switch(mpu1.getAccelerometerRange()) {
case MPU6050_RANGE_2_G:
  Serial.println("+-2G");
  break;
case MPU6050_RANGE_4_G:
  Serial.println("+-4G");
  break;
case MPU6050_RANGE_8_G:
  Serial.println("+-8G");
  break;
case MPU6050_RANGE_16_G:
 Serial.println("+-16G");
  break;
}
mpu1.setGyroRange(MPU6050_RANGE_500_DEG);
Serial.print("Gyro range set to: ");
switch (mpu1.getGyroRange()) {
case MPU6050_RANGE_250_DEG:
  Serial.println("+- 250 deg/s");
  break;
case MPU6050_RANGE_500_DEG:
  Serial.println("+- 500 deg/s");
  break;
case MPU6050_RANGE_1000_DEG:
  Serial.println("+- 1000 deg/s");
  break;
case MPU6050_RANGE_2000_DEG:
  Serial.println("+- 2000 deg/s");
  break;
}
mpu1.setFilterBandwidth(MPU6050_BAND_21_HZ);
Serial.print("Filter bandwidth set to: ");
switch (mpu1.getFilterBandwidth()) {
case MPU6050_BAND_260_HZ:
  Serial.println("260 Hz");
  break;
case MPU6050_BAND_184_HZ:
  Serial.println("184 Hz");
  break;
case MPU6050_BAND_94_HZ:
  Serial.println("94 Hz");
  break;
case MPU6050_BAND_44_HZ:
  Serial.println("44 Hz");
  break;
case MPU6050_BAND_21_HZ:
  Serial.println("21 Hz");
  break;
case MPU6050_BAND_10_HZ:
  Serial.println("10 Hz");
  break;
case MPU6050_BAND_5_HZ:
  Serial.println("5 Hz");
  break;
}

/* Initialise the 2 sensor */
tcaselect(1);
mpu2.setAccelerometerRange(MPU6050_RANGE_8_G);
Serial.print("Accelerometer range set to: ");
switch(mpu1.getAccelerometerRange()) {
case MPU6050_RANGE_2_G:
  Serial.println("+-2G");
  break;
case MPU6050_RANGE_4_G:
  Serial.println("+-4G");
  break;
case MPU6050_RANGE_8_G:
  Serial.println("+-8G");
  break;
case MPU6050_RANGE_16_G:
 Serial.println("+-16G");
  break;
}
mpu2.setGyroRange(MPU6050_RANGE_500_DEG);
Serial.print("Gyro range set to: ");
switch (mpu1.getGyroRange()) {
case MPU6050_RANGE_250_DEG:
  Serial.println("+- 250 deg/s");
  break;
case MPU6050_RANGE_500_DEG:
  Serial.println("+- 500 deg/s");
  break;
case MPU6050_RANGE_1000_DEG:
  Serial.println("+- 1000 deg/s");
  break;
case MPU6050_RANGE_2000_DEG:
  Serial.println("+- 2000 deg/s");
  break;
}
mpu2.setFilterBandwidth(MPU6050_BAND_21_HZ);
Serial.print("Filter bandwidth set to: ");
switch (mpu1.getFilterBandwidth()) {
case MPU6050_BAND_260_HZ:
  Serial.println("260 Hz");
  break;
case MPU6050_BAND_184_HZ:
  Serial.println("184 Hz");
  break;
case MPU6050_BAND_94_HZ:
  Serial.println("94 Hz");
  break;
case MPU6050_BAND_44_HZ:
  Serial.println("44 Hz");
  break;
case MPU6050_BAND_21_HZ:
  Serial.println("21 Hz");
  break;
case MPU6050_BAND_10_HZ:
  Serial.println("10 Hz");
  break;
case MPU6050_BAND_5_HZ:
  Serial.println("5 Hz");
  break;
}

/* Initialise the 3rd sensor */
tcaselect(2);
mpu3.setAccelerometerRange(MPU6050_RANGE_8_G);
Serial.print("Accelerometer range set to: ");
switch(mpu1.getAccelerometerRange()) {
case MPU6050_RANGE_2_G:
  Serial.println("+-2G");
  break;
case MPU6050_RANGE_4_G:
  Serial.println("+-4G");
  break;
case MPU6050_RANGE_8_G:
  Serial.println("+-8G");
  break;
case MPU6050_RANGE_16_G:
 Serial.println("+-16G");
  break;
}
mpu3.setGyroRange(MPU6050_RANGE_500_DEG);
Serial.print("Gyro range set to: ");
switch (mpu1.getGyroRange()) {
case MPU6050_RANGE_250_DEG:
  Serial.println("+- 250 deg/s");
  break;
case MPU6050_RANGE_500_DEG:
  Serial.println("+- 500 deg/s");
  break;
case MPU6050_RANGE_1000_DEG:
  Serial.println("+- 1000 deg/s");
  break;
case MPU6050_RANGE_2000_DEG:
  Serial.println("+- 2000 deg/s");
  break;
}
mpu3.setFilterBandwidth(MPU6050_BAND_21_HZ);
Serial.print("Filter bandwidth set to: ");
switch (mpu1.getFilterBandwidth()) {
case MPU6050_BAND_260_HZ:
  Serial.println("260 Hz");
  break;
case MPU6050_BAND_184_HZ:
  Serial.println("184 Hz");
  break;
case MPU6050_BAND_94_HZ:
  Serial.println("94 Hz");
  break;
case MPU6050_BAND_44_HZ:
  Serial.println("44 Hz");
  break;
case MPU6050_BAND_21_HZ:
  Serial.println("21 Hz");
  break;
case MPU6050_BAND_10_HZ:
  Serial.println("10 Hz");
  break;
case MPU6050_BAND_5_HZ:
  Serial.println("5 Hz");
  break;
}


/* Display some basic information on this sensor */
tcaselect(0);
displaySensorDetails(&mpu1);
tcaselect(1);
displaySensorDetails(&mpu2);
tcaselect(2);
displaySensorDetails(&mpu2);
}

void loop(void)
{
/* Get a new sensor event */
sensors_event_t a, g, temp;
tcaselect(0);
mpu1.getEvent(&a, &g, &temp);
/* Display the results (magnetic vector values are in micro-Tesla (uT)) */
Serial.print("Sensor #1 - ");
//Serial.print("X: "); Serial.print(event.magnetic.x); Serial.print(" ");
//Serial.print("Y: "); Serial.print(event.magnetic.y); Serial.print(" ");
//Serial.print("Z: "); Serial.print(event.magnetic.z); Serial.print(" ");Serial.println("uT");
Serial.print("Acceleration X: ");
Serial.print(a.acceleration.x);
Serial.print(", Y: ");
Serial.print(a.acceleration.y);
Serial.print(", Z: ");
Serial.print(a.acceleration.z);
Serial.println(" m/s^2");

tcaselect(2);
mpu2.getEvent(&a, &g, &temp);
/* Display the results (magnetic vector values are in micro-Tesla (uT)) */
Serial.print("Sensor #2 - ");
Serial.print("X: "); Serial.print(event.magnetic.x); Serial.print(" ");
Serial.print("Y: "); Serial.print(event.magnetic.y); Serial.print(" ");
Serial.print("Z: "); Serial.print(event.magnetic.z); Serial.print(" ");Serial.println("uT");
Serial.print("Acceleration X: ");
Serial.print(a.acceleration.x);
Serial.print(", Y: ");
Serial.print(a.acceleration.y);
Serial.print(", Z: ");
Serial.print(a.acceleration.z);
Serial.println(" m/s^2");
delay(500);
}

In this configuration All of my mpu sensors are sending back unreasonable numbers for acceleration and temperature. Am I initializing my mpus correctly in my code?

timemage · Accepted Answer · 2021-09-20 18:07:32Z

It seems like you would need to call .begin() on your Adafruit_MPU6050 instances, like the examples do.

So, following the pattern, in setup() you would need to:

 tcaselect(0);
 if (!mpu1.begin()) {
    Serial.println(F("Failed to find MPU6050 chip 1"));
    while (1) {
      delay(10);
    }
 }

 tcaselect(1);
 if (!mpu2.begin()) {
    Serial.println(F("Failed to find MPU6050 chip 2"));
    while (1) {
      delay(10);
    }
 }

 tcaselect(2);
 if (!mpu3.begin()) {
    Serial.println(F("Failed to find MPU6050 chip 3"));
    while (1) {
      delay(10);
    }
 }

I see you're removing some repetition with functions. I'm guessing you just haven't gotten to doing that with the repeated switch statements for printing frequencies and such. You may want to put your mcu1/mcu2/mcu3 into an array instead for similar reasons.

An array of Adafruit_MPU6050:

Adafruit_MPU6050 mpus[3];

The code for calling begin() could look something like:

size_t index = 0;
for (auto &an_mpu: mpus) {
  tcaselect(index);
  if (!an_mpu.begin()) {
    Serial.print(F("Failed to find MPU6050 chip, mpu["));
    Serial.print(index);
    Serial.println(']');
    Serial.println(F("Halting..."));
    while (1) {
      delay(10);
    }
  }

  ++index;
}

Thanks for the nice and helpful answer :), usually people are pretty condescending — cch, Sep 24, 2021 at 15:03

starship15 · Accepted Answer · 2021-09-22 14:10:34Z

You don't need the I2C multiplexors at all - I currently have seven MPU6050 modules being managed by one Teensy 3.5 chip. Four MPU6050's are on one of the T3.5's I2C busses, and the remaining three are on another. I could run them all from just one I2C bus, but I split them just for wiring convenience. The 'trick' is to replace the I2C address of each MPU6050 in turn in the setup() routine, as shown by the code associated with the blog post referenced below

See this post and related ones on my blog site 'Paynter's Palace'.

I've been using this technique for quite a while now, so let me know if you have any additional questions.

22 Sept 21 edit:

Here's the function that handles address initialization for the four MPU6050's on the Wire2 I2C bus:

bool InitWire2Sensors()
{
  delay(1000);
  Serial.printf("Initializing VL53L0X Sensor Array Elements on Wire2\n");
  bool retval = true;

  //Put all sensors in reset mode by pulling XSHUT low
  digitalWrite(LF_XSHUT_PIN, LOW);
  digitalWrite(LC_XSHUT_PIN, LOW);
  digitalWrite(LR_XSHUT_PIN, LOW);
  digitalWrite(Rear_XSHUT_PIN, LOW);

  //left-front
  //input w/o pullups sets line to high impedance so XSHUT pullup to 3.3V takes over
  pinMode(LF_XSHUT_PIN, INPUT);
  delay(10);

  if (!lidar_LF.init())
  {
    Serial.println("Failed to detect and initialize LF sensor!");
    retval = false;
  }
  else
  {
    Serial.printf("lidar_LF successfully initialized at %x\n", lidar_LF.getAddress());
    lidar_LF.setMeasurementTimingBudget(20000);
    lidar_LF.startContinuous();


    lidar_LF.setAddress(DEFAULT_VL53L0X_ADDR + 4);
    Serial.printf("lidar_LF. address is now 0x%x\n", lidar_LF.getAddress());
  }


  //now bring lidar_LC only out of reset and set it's address
  //input w/o pullups sets line to high impedance so XSHUT pullup to 3.3V takes over
  pinMode(LC_XSHUT_PIN, INPUT);
  delay(10);

  if (!lidar_LC.init())
  {
    Serial.println("Failed to detect and initialize LC sensor!");
    retval = false;
  }
  else
  {
    Serial.printf("lidar_LC successfully initialized at %x\n", lidar_LC.getAddress());
    lidar_LC.setMeasurementTimingBudget(20000);
    lidar_LC.startContinuous();


    lidar_LC.setAddress(DEFAULT_VL53L0X_ADDR + 5);
    Serial.printf("lidar_LC. address is now 0x%x\n", lidar_LC.getAddress());
  }


  //now bring lidar_LR only out of reset and set it's address
  //input w/o pullups sets line to high impedance so XSHUT pullup to 3.3V takes over
  pinMode(LR_XSHUT_PIN, INPUT);
  delay(10);

  if (!lidar_LR.init())
  {
    Serial.println("Failed to detect and initialize LR sensor!");
    retval = false;
  }
  else
  {
    Serial.printf("lidar_LR successfully initialized at %x\n", lidar_LR.getAddress());
    lidar_LR.setMeasurementTimingBudget(20000);
    lidar_LR.startContinuous();


    lidar_LR.setAddress(DEFAULT_VL53L0X_ADDR + 6);
    Serial.printf("lidar_LR. address is now 0x%x\n", lidar_LR.getAddress());
  }

  //now bring lidar_Rear only out of reset and set it's address
  //input w/o pullups sets line to high impedance so XSHUT pullup to 3.3V takes over
  pinMode(Rear_XSHUT_PIN, INPUT);
  delay(10);

  if (!lidar_Rear.init())
  {
    Serial.println("Failed to detect and initialize Rear sensor!");
    retval = false;
  }
  else
  {
    Serial.printf("lidar_Rear successfully initialized at %x\n", lidar_Rear.getAddress());
    lidar_Rear.setMeasurementTimingBudget(20000);
    lidar_Rear.startContinuous();


    lidar_Rear.setAddress(DEFAULT_VL53L0X_ADDR + 7);
    Serial.printf("lidar_Rear. address is now 0x%x\n", lidar_Rear.getAddress());
  }
  //input w/o pullups sets line to high impedance so XSHUT pullup to 3.3V takes over
  pinMode(LR_XSHUT_PIN, INPUT);
  delay(10);

  if (!lidar_LR.init())
  {
    Serial.println("Failed to detect and initialize LR sensor!");
    retval = false;
  }
  else
  {
    Serial.printf("lidar_LR successfully initialized at %x\n", lidar_LR.getAddress());
    lidar_LR.setMeasurementTimingBudget(20000);
    lidar_LR.startContinuous();


    lidar_LR.setAddress(DEFAULT_VL53L0X_ADDR + 2);
    Serial.printf("lidar_LR. address is now 0x%x\n", lidar_LR.getAddress());
  }

  return retval;
}

Frank

Wow I was really confused about the Teensy 3.5 chip name, I thought you just meant a small chip. Thanks for the helpful answer :) — cch, Sep 24, 2021 at 15:05

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