Due i2c Serial conflict

Hardware Arduino Due
1

I have another board sending 3-byte packets of data to the Due Serial1 port at about 100 packets/second. I also am reading an IMU via i2c at about 200/sec. This always crashes after a few seconds. The crashes only occur when data is being received on the serial port. I have similar results on the Serial2 port. Here is a code snippit that give this result:

#include <Wire.h>
#include <LSM6.h>

#define ADDRESS 0b1101011
#define OUTX_L_G 0x22
#define OUTX_L_XL 0x28

 
LSM6 lsm6;
int z = 0;

void setup() {
  Serial1.begin(115200);    // UP Board
  Serial.begin(115200);
  
  pinMode(13,OUTPUT);  // Status LED, also blue LED
  Wire.begin();
  if (!lsm6.init())   Serial.println("IMU initialize failed!"); 

  lsm6.enableDefault();
  lsm6.writeReg(LSM6::INT1_CTRL, 0X02); // Accel data ready on INT1
  lsm6.writeReg(LSM6::INT2_CTRL, 0X01); // Gyro data ready on INT2
  lsm6.writeReg(LSM6::CTRL2_G, 0X5C);   // Gyro 2000fs, 208hz
  lsm6.writeReg(LSM6::CTRL1_XL, 0X50);  // Accel 2g, 208hz

} // end setup()


void loop() { //Main Loop
  static unsigned int tRead = 0;
  while(true) {
    
    while (Serial1.available()) {
      byte b = Serial1.read();
      Serial.print(b); Serial.print(" ");
      if (b == 0) Serial.println();
     }
     
      unsigned int  t = micros();
      if (t > tRead) {
        tRead = t + 5000;
        readGyro();
        readAcc();
        Serial.println(z);
     }
  }

} // End loop().  



void readGyro(void)
{
  Wire.beginTransmission(ADDRESS);
  Wire.write(OUTX_L_G);
  Wire.endTransmission();
  Wire.requestFrom(ADDRESS, (uint8_t)6);
  while (Wire.available() < 6) ;
  uint8_t xlg = Wire.read();
  uint8_t xhg = Wire.read();
  uint8_t ylg = Wire.read();
  uint8_t yhg = Wire.read();
  uint8_t zlg = Wire.read();
  uint8_t zhg = Wire.read();

  // combine high and low bytes
  z = (int16_t)(zhg << 8 | zlg);
}


void readAcc(void)
{
  Wire.beginTransmission(ADDRESS);
  Wire.write(OUTX_L_XL);
  Wire.endTransmission();
  Wire.requestFrom(ADDRESS, (uint8_t)6);

  while (Wire.available() < 6) ;
  
  uint8_t xla = Wire.read();
  uint8_t xha = Wire.read();
  uint8_t yla = Wire.read();
  uint8_t yha = Wire.read();
  uint8_t zla = Wire.read();
  uint8_t zha = Wire.read();
}

the output looks like this:

151 48 0 
151 48 0 
151 48 0 
-18
151 48 0 
151 48 0 
-20
151 48 0 
151 48 0 
151 48 0 
-20
151 48 0 
151 48 0 
-18
151 48 0 
151 48 0 
151 48 0 
-19
151 48 0 
151 48 0 
-21
151 48 0 
151 48 0 
151 48 0

Any ideas? It sure feels like a library bug to me. Should I file a bug report?

2

Hello there!

Have you tried getting each library to work independently? That would be the best way to identify if there is a clash between the two.

3

Yes. Both libraries work just fine by themselves. I have recently discovered a previous post, I2C interference by serial communication, that may be relevant. I will pursue that and post an update.

4

Hi
I have a gps connected to the serial2 port on a Due and an I2C LCD from Robotshop that is supposed to work with the Due. The GPS data crashes and LCD hangs after a short period 5 to 20 seconds. I saw a solution on a 2015 post suggesting 330 ohm resisters in series on the I2C inputs. Can anyone confirm that this will work
Thanks

5

I can't confirm that this will work, but adding a resistor in serie will not harm the uc but will smooth the signal in order to reduce EMI spikes on the bus.

6

Thanks for your response. I will try it out
regards