 
     // limit data rate
     if(delta >= DELAY_SLOW) {
-        // switch to precise reference (2.56V)
-        analogReference(INTERNAL);
-
         // analog inputs (battery)
         raw_bat0 = analogRead(A0);      // J4 (pin 1)
         raw_bat0 = analogRead(A0);      // J4 (pin 1)

#define ADC_INTERNAL_MV 2.483f      // manual calibration (was 2.502f)
#define ADC_DEFAULT_V 0.004887f     // uncalibrated
#define ADC_DEFAULT_MV 4.887f       // uncalibrated

#define LED_PIN 13


        report_indicators();

        
        // send timestamp
        Serial.print("$TIME,");
        Serial.println(time_env, DEC);
