safe to remove power led from ds3231 clock module?

Hi All,

I'm sorry if this isn't the proper place to ask this question but none of the other were too :D Got this DS3231 AT24C32 IIC module from Ebay (http://www.ebay.com.au/itm/DS3231-AT24C32-IIC-Memory-Module-Arduino-Module-High-Precision-Clock-3-3-5-5V-/271302733176?ssPageName=ADME:L:OC:US:3160).

Long story short: trying to keep power consumption to a bare minimum.

I'm powering the module with D4 in series with a 220 ohm resistor (that line is also capped to gnd via a 0.1uF cap). D4 is set to HIGH whenever I need to power up the clock. In this case every time the module's INT/SQW pin goes low (by setting an alarm) it fires a low level interrupt on D2 to wake up the micro-controller and do whatever it needs to. After that I set D4 to LOW and power off the module. I have the module's INT/SQW pin pulled up to 5V with a 10k resistor. Everything works smoothly except that the power led on the module remains lit after setting D4 to LOW, albeit very dimly. Didn't expect to get that led lit via the INT/SQW line... XD Since it's draining power my question is if it's safe to remove the power led from the module - or if anyone else has done it too.

Here's the relevant code (loop fx) btw:

    // WORK SECTION
    // power up clock chip
    digitalWrite (CLOCK_POWER, HIGH);
    pinMode (CLOCK_POWER, OUTPUT);

    // activate I2C
    Wire.begin();

    if (DS3231_triggered_a2()) {
        Serial.println(" -> alarm2 has been triggered");
        set_next_alarm();
        // clear a2 alarm flag and let INT go into hi-z
        DS3231_clear_a2f();
    }

    Serial.println("I'm awake...");

    struct ts t;
    DS3231_get(&t);
    Serial.print(t.hour);
    Serial.print(":");
    Serial.println(t.min);
    delay(1000);


    // finished with clock
    pinMode (CLOCK_POWER, INPUT);
    digitalWrite (CLOCK_POWER, LOW);


    // SLEEP SECTION
    // power down everything we don't need

    // turn off I2C
    TWCR &= ~(_BV(TWEN) | _BV(TWIE) | _BV(TWEA));
    // turn off I2C pull-ups
    digitalWrite (A4, LOW);
    digitalWrite (A5, LOW);

    // disable ADC
    ADCSRA = 0;

    set_sleep_mode (SLEEP_MODE_PWR_DOWN);
    sleep_enable();
    // Do not interrupt before we go to sleep, or the
    // ISR will detach interrupts and we won't wake.
    noInterrupts ();
    // will be called when pin D2 goes low
    attachInterrupt (0, clockWake, LOW);
    // turn off brown-out enable in software
    // BODS must be set to one and BODSE must be set to zero within four clock cycles
    MCUCR = bit (BODS) | bit (BODSE);
    // The BODS bit is automatically cleared after three clock cycles
    MCUCR = bit (BODS);
    // We are guaranteed that the sleep_cpu call will be done
    // as the processor executes the next instruction after
    // interrupts are turned on.
    interrupts (); // one cycle
    sleep_cpu (); // one cycle

    // WAKES UP HERE

TIA, Pedro

Looking in detail at the image and yes it looks like you can just remove the LED (or the 102 resistor next to it)

Riva: Looking in detail at the image and yes it looks like you can just remove the LED (or the 102 resistor next to it)

Thanks Riva for looking into it :) Karma be upon you ;)

pdoriam: Everything works smoothly except that the power led on the module remains lit after setting D4 to LOW, albeit very dimly. Didn't expect to get that led lit via the INT/SQW line... XD Since it's draining power my question is if it's safe to remove the power led from the module - or if anyone else has done it too.

TIA, Pedro

Hi Pedro, but you tell that you disconnect VCC from RTC pin your RTC still working? An still power led is powered? If i disconnect VCC from RTC it's running with battery but only for keep correct time, alarms, led, etc don't work it's all down except timing.

I need alarms even when running on battery power. You know how to do it?