MKR Zero uA sleep current

[LDBM]

Hi,

I am looking at what is achievable in terms of sleep current with a MKR Zero. On the MKRWAN1310 forum it looks like ~ 100uA is achievable. As posted there I can only get to ~ 600uA. I am re-posting my code below.

I am using a MKR Zero, powered via the J2 pin with a 3.7 Lipo batt. I measure the current with a CurrentRanger.

I started from the RTC example, tried both the rtc.standbyMode() and LowPower.deepSleep() calls : same result.

Any help appreciated. Thx.

#include <RTCZero.h>
#include <ArduinoLowPower.h>

/* Create an rtc object */
RTCZero rtc;

/* Change these values to set the current initial time */
const byte seconds = 0;
const byte minutes = 00;
const byte hours = 17;

/* Change these values to set the current initial date */
const byte day = 24;
const byte month = 11;
const byte year = 20;

void setup()
{
   // Set digital pins to input  to save on current drain
 for (int i=0; i < 15; i++) 
 {
   pinMode(i, INPUT_PULLUP);
 }
  
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, LOW);

  rtc.begin();

  rtc.setTime(hours, minutes, seconds);
  rtc.setDate(day, month, year);

  rtc.setAlarmTime(17, 00, 20);
  rtc.enableAlarm(rtc.MATCH_HHMMSS);

  rtc.attachInterrupt(alarmMatch);

  // detach USB so chip is asleep
  USBDevice.detach();
  rtc.standbyMode();
}

void loop()
{
  //rtc.standbyMode();    // Sleep until next alarm match
  LowPower.deepSleep();
}

void alarmMatch()
{
  digitalWrite(LED_BUILTIN, HIGH);
  USBDevice.attach();
}

[LDBM]

Resolved: see this thread. , MKR Zero sleep with ~ 65uA

[sslupsky]

FYI, the link does not work.

I would expect you could achieve much lower current with a MKR Zero than 65uA. To do so however would require that you bypass the power supply on the zero. Arduino power supplies are not particularly power efficient.

[LDBM]

Thx for the heads-up updated link : How can I achieve the 104µA power consumption? - #25 by LDBM

some of the images were lost since the forum changed.

I am not ready to burn things on the board as what to knock off may change depending on the type of board and I am not super dialed on how to do this cleanly.
L.

[sslupsky]

I have a custom SAMD21 board that sleeps at about 18uA. With some tweaks you can get the MKR WAN 1310 to sleep at about 18uA as well.

[LDBM]

Good to know. Did you replace the power supply chips from the original design, or just sw settings? Thx.