ATTiny441 Halts if AnalogRead present after few cycles

[kais58]

With this code, after a few dozen cycles I stop seeing anything on Serial

#include <Wire.h>

void setup() {
  Serial.begin(57600);
  Wire.begin(0x41);
  Serial.print("Hello world\n");

}

void loop() {
  int temp_y = analogRead(PIN_PB0);
  Serial.print(temp_y);
  Serial.print("loop\n");

}

Only changing it to this, it continues indefintely

#include <Wire.h>

void setup() {
  Serial.begin(57600);
  Wire.begin(0x41);
  Serial.print("Hello world\n");

}

void loop() {
  Serial.print("loop\n");

}

I've brought it down to this minimal case, but have no idea why this would be, any help?

[SpenceKonde]

What is the involvement of Serial here? I see you starting it up as slave, but I don't see anything else relating to it there...

[kais58]

The serial is there just for debugging, trying to figure out why it was stopping, though removing the Wire.begin makes it work, I'm trying to use it as a I2C slave device and send values it reads to the master

[kais58]

#include <Wire.h>

volatile byte i2c_reg = 0;  //stores last byte transmitted
volatile bool flag = 0;     //flag to set after y val sent
signed char x_pos = 0;  //stores x and y vals to be sent
signed char y_pos = 0;

void requestEvent() {
  switch (i2c_reg) {
    case 0x10:
      Wire.write(x_pos); //x val
      break;
    case 0x11:
      Wire.write(y_pos); //y val
      flag = 1;
      break;
    case 0x0F: //Ctrl 1 regester
      Wire.write(0b11110001);
      break;
    case 0xFF:
      Wire.write(0b00000000);
      break;
    case 0x0C:
      Wire.write(0x0C);
      break;
  }
}

void receiveEvent(int bytes) {
  while (Wire.available()) {
    i2c_reg = Wire.read();
  }
}



void setup() {
  //Serial.begin(57600);
  Wire.begin(0x41);                // join i2c bus with address 0x41 
  pinMode(PIN_PA4, INPUT);
  pinMode(PIN_PA6, INPUT_PULLUP);
  Wire.onReceive(receiveEvent);    // I2C events
  Wire.onRequest(requestEvent);
  pinMode(PIN_PA0, INPUT);
  pinMode(PIN_PB0, INPUT);
  //Serial.print("Hello world\n");
}


void loop() {
  int temp_x = analogRead(PIN_PA0); //map(analogRead(10), 1023, 0, -128, 127));  //scales analog inputs to correct size
  int temp_y = analogRead(PIN_PB0); //map(analogRead(0), 0, 1023, -128, 127));
  //Serial.print("loop\n");
  //Serial.print(temp_y);
  if (flag) {
    noInterrupts();
    flag = 0;
    x_pos = temp_x;
    y_pos = temp_y;
    interrupts();
  }
}

this is my original code, that I stripped out until I got the smallest case where it breaks as above

[SpenceKonde]

So is it hanging entirelty, or is just analogRead no longer happening? Like does it still respond to I2C?

[SpenceKonde]

Or is it holding the clock line low (clock stretching) indefinitely)?

[kais58]

Everything stops, I2C and Serial, will check if SCL is low

[kais58]

VCC 2.5V SCL 2.3V so still high