One bad temp reading causes failed print

[north90ty]

I had some trouble with prints failing because the temperature was dropping. I guess it is caused by a bad temperature reading, triggering this code in Sprinter.pde:
#ifdef MINTEMP
if(current_raw <= minttemp)
target_raw=0;
#endif

If instead of setting the target_raw to 0 the heater_pin can be set low, so if the next reading of the temperature sensor is ok the printer keeps on managing the heater.

I changed Sprinter.pde by moving #ifdef MINTEMP to where the heater pin is managed:

if (TEMP_0_PIN > -1) || defined (HEATER_USES_MAX6675) || defined (HEATER_USES_AD595)

#ifdef PIDTEMP
  error = target_raw - current_raw;
  pTerm = (PID_PGAIN * error) / 100;
  temp_iState += error;
  temp_iState = constrain(temp_iState, temp_iState_min, temp_iState_max);
  iTerm = (PID_IGAIN * temp_iState) / 100;
  dTerm = (PID_DGAIN * (current_raw - temp_dState)) / 100;
  temp_dState = current_raw;
  analogWrite(HEATER_0_PIN, constrain(pTerm + iTerm - dTerm, 0, PID_MAX));
#else
  if(current_raw >= target_raw)
  {
    WRITE(HEATER_0_PIN,LOW);
    #if LED_PIN>-1
        WRITE(LED_PIN,LOW);
    #endif
  }
  else 
  {
    WRITE(HEATER_0_PIN,HIGH);
    #if LED_PIN > -1
        WRITE(LED_PIN,HIGH);
    #endif
  }

// ----------------------------------------------------
// if bad temp reading turn heater off for now
//--
#ifdef MINTEMP
if(current_raw <= minttemp) {
WRITE(HEATER_0_PIN,LOW);
#if LED_PIN>-1
WRITE(LED_PIN,LOW);
#endif
}
#endif
//---------------------------------
#endif

Thanks,
Frank

[marcopiraccini]

I have the very same problem...his fix has been pulled?