XIAO BLE Sense in deep sleep mode

[AdamM68]

Getting lower power consumption on Seeed XIAO nRF52840

I found good hints on this topic page XIAO BLE Sense in deep sleep mode. But many of the code snippets I saw in the thread were not working as I expected. I dug into the arduino core try to understand the underlying implementation. Based on my digging, I developed the below sketch. The arduino loop runs at 3uA (with a major caveat). It demonstrates system_off sleep with wake up on gpio interrupt, system_on sleep, and a low latency Arduino main loop. More info on my findings below the sketch. (I …

[Gordy7]

Here is a rough demo program that draws approx 1uA when idle.
Seeed XIAO nRF52840 (not sense).
LEDs a turned on after a couple of push button switches are polled in Setup after switch interrupts.
Program needs an expert to comment and tidy up.

[NRF52]

Hi !
Thank you for your advice.
My project uses a bare nRF52840 chip (there is no spi flash on the board and there is no microphone and there is no sense module).
But the current in sleep mode is still 8 µA.

[Gordy7]

Here are a couple my of tests and current results following NRF52 simple code for shutdown:

// Basic_Shutdown_20230522_01.ino
// 3.2 volts on 3V3 to GND
// current 21.2 uA during Delay
// current 18.0 uA after Delay
//
void setup()
{
delay(10000);
NRF_POWER->SYSTEMOFF = 1;
}
void loop()
{
}

// Basic_Shutdown_20230522_02.ino
// 3.2 volts on 3V3 to GND
// current 4.4 uA during Delay.
// Current 1.1 uA after Delay
//
#include <bluefruit.h>
#include <Adafruit_FlashTransport.h>
//
void setup()
{
//
Adafruit_FlashTransport_QSPI flashTransport;
Bluefruit.begin();
flashTransport.begin();
flashTransport.runCommand(0xB9);
flashTransport.end();
//
delay(10000);
NRF_POWER->SYSTEMOFF = 1;
}
void loop()
{
}

[NRF52]

Thank you very much!
I 'll check it tonight !

[NRF52]

AdamM68, Gordy7 !

Thank you very much for your help !
Everything worked out, the current is less than 1 µA!

[Philipp_W]

@Gordy7

// Basic_Shutdown_20230522_02.ino
// 3.2 volts on 3V3 to GND
// current 4.4 uA during Delay.
// Current 1.1 uA after Delay
//
#include <bluefruit.h>
#include <Adafruit_FlashTransport.h>
//
void setup()
{
//
Adafruit_FlashTransport_QSPI flashTransport;
Bluefruit.begin();
flashTransport.begin();
flashTransport.runCommand(0xB9);
flashTransport.end();
//
delay(10000);
NRF_POWER->SYSTEMOFF = 1;
}
void loop()
{
}

When I run this, I get 733.77uA during the delay and 731.69uA After. Any Idea what I might be missing? Nothing else is attached.

[Gordy7]

I am not familiar with the Data Logger you are using.
I used a DMM on the uA range connected between the 3.2v battery and the 3V3 terminal on the XIAO nRF.
I was careful to make sure that the USB connection to the XIAO was removed.

[hobbya]

Some questions regarding your set up but not sure if these will help:

1. You have applied 4.097V but Gordy7 only applied 3.2V
2. Gordy7 applied the voltage across 3V3 and GND pins

The Xiao board can only accept voltage > 3.6V at the battery pins, if you apply 4.097V at 3V3 pin you will be stressing your board.

[AdamM68]

Has anyone checked this issue ? :

• how do You connect xiao for making measurements ?
  Maybe there is an issue when You power the xiao board via different paths
  1: USB port with 5v
  2: battery port with 3,6 - 4,2 v
  3: 3v3 pin