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Hi,

I am using Arduino 1.0.3, a Dorkbot Dorkboard minimal clone and a MCP23008 I2C expander port.

After some time, the I/O port stops updating while the rest of the program keeps running.  I've reduced the program to a port test program - sending a counter to I/O port driving LEDS.

Minimal code is

/*

Why does Wire functions stop working on the pump control design?

Experiments to work it out.


*/

#include <Wire.h>

const byte ADR23008 = 0x21;
const byte IOR = 0x00;
const byte GPIO = 0x09;

unsigned long reftime;
unsigned long nowtime;
unsigned long epoch = 1000;  //1 second

byte LEDS;

void setup() {
  Wire.begin();
  Wire.beginTransmission(ADR23008);
  Wire.write(IOR);
  Wire.write(0x00);  //set all outputs on i2c MCP23008
  Wire.endTransmission();
 
  LEDS = 0x00;
  reftime = millis();
}

void loop () {
  nowtime = millis();
  if (nowtime - reftime >= epoch)  {
    reftime = reftime + epoch;
   PumpControl();
  }
}

void PumpControl() {
  Wire.beginTransmission(ADR23008);
  Wire.write(GPIO);
  Wire.write(~LEDS);
  Wire.endTransmission(0);
  LEDS++;
}
 
At some time the I/O port just stops responding.

Anybody had a similar issue?

Best REgards

Barry