multiple mpu9250 using tca9548a with esp32

Question

I'm using ESP32 and 1 sensor mpu9250(only for test) with tca9548a, connections are:

TCA <-> ESP

VIN - VCC

GND - GND

SDA - GPIO21

SCL - GPIO22

TCA <-> MPU

SD2 - SDA

SC2 - SCL

VIN - VIN

GND - GND

And my code here:

#include <SparkFunMPU9250-DMP.h>
#include <Wire.h>
#define TCAADDR 0x70
void tcaselect(uint8_t i) {
 if (i > 7) return;
 
 Wire.beginTransmission(TCAADDR);
 Wire.write(1 << i);
 Wire.endTransmission(); 
}
MPU9250_DMP imu;
void setup() 
{
 Serial.begin(115200);
 Wire.begin();
 tcaselect(2);
 if (imu.begin() != INV_SUCCESS)
 {
 while (1)
 {
 Serial.println("Unable to communicate with MPU-9250");
 Serial.println("Check connections, and try again.");
 Serial.println();
 delay(5000);
 }
 }
 
 imu.dmpBegin(DMP_FEATURE_6X_LP_QUAT | // Enable 6-axis quat
 DMP_FEATURE_GYRO_CAL, // Use gyro calibration
 10); // Set DMP FIFO rate to 10 Hz
 delay(10000);
}
void loop() 
{
 tcaselect(2);
 imu.dmpUpdateFifo();
 float q0 = imu.calcQuat(imu.qw);
 float q1 = imu.calcQuat(imu.qx);
 float q2 = imu.calcQuat(imu.qy);
 float q3 = imu.calcQuat(imu.qz);
 Serial.println("Q: " + String(q0, 4) + ", " +
 String(q1, 4) + ", " + String(q2, 4) + 
 ", " + String(q3, 4));delay(10);
}

I need to get quaternions from the MPU sensor but I'm only getting zeros on the output.

enter image description here

Library that I used: https://github.com/rupin/SparkFun_MPU-9250-DMP_Arduino_Library

What could be wrong, my connection or library?

• Juraj: did you read the answer to this question? arduino.stackexchange.com/questions/70834/…
• chrisl: You could try adapting the I2C Scanner sketch to use the TCA9548a like you do. Then you can check if the MPU is really visible on the bus. I would think, that the Arduino cannot reach the MPUn thus giving only zeros
• TryHack Channel: @Juraj yes, I will try this method later. But now I'd like to figure out why my method doesn't work
• TryHack Channel: @chrisl It`s true, TCA scanner cannot find any addresses of MPU9250. Seems like clock stretching(idk). But now I use method of changing address of MPU that i use in 1 tick.

Answer 1

The solution is that I just removed the tca9548a from the circuit. Then I connected each AD0 pin to the corresponding GPIO ESP32 pins to turn on the sensor, I send a low signal to it, and a high signal to all the others. Thus, the library only works with a sensor whose address is 0x68.

There is example function from my sketch:

#include <SparkFunMPU9250-DMP.h>
/*INIT SENSORS*/
MPU9250_DMP imu;
MPU9250_DMP imu1;
const int sensor1 = 18;
const int sensor2 = 19;
String IMU_1Update(){
 String res;
 digitalWrite(sensor1, LOW); // 1st sensor enable - 0x68
 digitalWrite(sensor2, HIGH); // 2nd sensor disable - 0x69
 if ( imu1.fifoAvailable() ){
 if ( imu1.dmpUpdateFifo() == INV_SUCCESS){
 float q0 = imu1.calcQuat(imu1.qw);
 float q1 = imu1.calcQuat(imu1.qx);
 float q2 = imu1.calcQuat(imu1.qy);
 float q3 = imu1.calcQuat(imu1.qz);
 Serial.print("G1|");
 Serial.print(q0);
 Serial.print("|");
 Serial.print(q1);
 Serial.print("|");
 Serial.print(q2);
 Serial.print("|");
 Serial.print(q3);
 Serial.println("|");
 }
 }
 return res;
}