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Topic: MKRFox lowpower.sleep not working (Read 3779 times) previous topic - next topic



I can't get the lowpower to work... The board goes to sleep indefinitely. Replacing sleep with delay works fine.

Anybody an idea what can cause this? Simple setup with a onewire temperature sensor.

Here's the code. I'm new at this so probably some stupid mistake. Any help is appreciated.

#include <SigFox.h>
#include <ArduinoLowPower.h>
#include <OneWire.h>
#include <DallasTemperature.h>

#define UINT16_t_MAX  65536
#define INT16_t_MAX   UINT16_t_MAX/2

// Set debug to false to enable continuous mode
// and disable serial prints
int debug = false;
#define ONE_WIRE_BUS 2
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

typedef struct __attribute__ ((packed)) sigfox_message {
  uint8_t status;
  int16_t moduleTemperature;
  int16_t ExtTemperature1;
  int16_t ExtTemperature2;
  uint8_t lastMessageStatus;
} SigfoxMessage;

int16_t convertoFloatToInt16(float value, long max, long min) {
  float conversionFactor = (float) (INT16_t_MAX) / (float)(max - min);
  return (int16_t)(value * conversionFactor);

// stub for message which will be sent
SigfoxMessage msg;

void setup() {

  if (debug == true) {

    while (!Serial) {}

  if (!SigFox.begin()) {
    //something is really wrong, try rebooting

  //Send module to standby until we need to send a message

  //if (debug == true) {
    // Enable debug prints and LED indication if we are testing
 // }
  // start sensors

void loop()
 msg.status = 1;
  // if we get here it means that an event was received

  // lees temperaturen uit
  sensors.requestTemperatures(); // Send the command to get temperature readings
  float temperature1 = sensors.getTempCByIndex(0);
  float temperature2 = sensors.getTempCByIndex(1);
  msg.ExtTemperature1 = convertoFloatToInt16(temperature1, 60, -60);
  msg.ExtTemperature2 = convertoFloatToInt16(temperature2, 60, -60);


  // interne temperatuur bordje
  float temperature = SigFox.internalTemperature();
  msg.moduleTemperature = convertoFloatToInt16(temperature, 60, -60);

  if (debug == true) {
    Serial.println("temp1: " + String(temperature1));
    Serial.println("temp2: " + String(temperature2));
   Serial.println("Internal temp: " + String(temperature));
  // Clears all pending interrupts

  SigFox.write((uint8_t*)&msg, 12);

  msg.lastMessageStatus = SigFox.endPacket();

  if (debug == true) {
    Serial.println("Status: " + String(msg.lastMessageStatus));


  if (debug == true) {
    // spin forever, so we can test that the backend is behaving correctly
    while (1) {}

  //Sleep for 15 minutes
  LowPower.sleep(15 * 60 * 1000);


void reboot() {
  while (1);


Try to add this line to your setup function :
LowPower.attachInterruptWakeup(RTC_ALARM_WAKEUP, dummy, CHANGE);


Sorry for replying so late but this won't compile
   LowPower.attachInterruptWakeup(RTC_ALARM_WAKEUP, dummy, CHANGE);
exit status 1
'dummy' was not declared in this scope

Thanks for the tip, I keep on looking


OK... noob error

You have to add the dummy function in your sketch

void dummy() {
  // This function will be called once on device wakeup
  // You can do some little operations here (like changing variables which will be used in the loop)
  // Remember to avoid calling delay() and long running functions since this functions executes in interrupt context


what do you have to put in the dummy function ? a reboot / reset operation ? or keep empty like this and it'll start auto the loop void ?


what do you have to put in the dummy function ? a reboot / reset operation ? or keep empty like this and it'll start auto the loop void ?
it could be any simple thing. Just declare a variable there. Something like:

void dummy() {
  volatile int aaa=0;



I've had the same problem with the waking up from lowpower.sleep().

It seems that you have to use Serial1 (connected to pins 13&14, which are the TX & RX connectors) instead of the normal USB connector as the USB port may get confused during wakeup.  
I just ordered this FTDI- Adapter and hope that it will allow me serial print out. Otherwise, I will just connect the mkr fox to a battery and not have ANY SERIAL connection, thus sending the data directly to SigFox.
Another thing I also read is that you may have problems with the computer recognizing the port, then you may need to install the correct driver for the FT232RL driver.

I got this information from the Author Antine de Chassey and the Video. I hope my conclusion is right and will keep you posted :)


So I connected the FTDI - USB and installed the corresponding driver. The Port shows on Arduino 1.8.13. However, I was not able to communicate with my Arduino at all (need to verify if maybe the driver is not working correctly/ was the wrong one/ connected the pins wrong).
Consequently, I quit the serial communication and send the data directly to SigFox after the Arudino woke up from deepSleep() and made the measurements it successfully transmitted the data to SigFox. I had the code running for 24h just to verify if any hick-ups occurred.

Strangely when using the Sigfox commands the power consumption in deepSleep rose from 13uA to 60uA. Any one knows, why this might happen?
Kind regards,

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