XIAO BLE Sense in deep sleep mode

[Matthieu_Charbonnier]

@AdamM68

#include <Arduino.h>
#include <Adafruit_TinyUSB.h> // for Serial
#include <bluefruit.h>

/* SoftwareTimer is a helper class that uses FreeRTOS software timer
 * to invoke callback. Its periodic timing is flexible as opposed to
 * hardware timer and cannot be faster than rtos's tick which is configured
 * at  ~1 ms interval.
 *
 * If you need an strict interval timing, or faster frequency, check out
 * the hw_systick sketch example that use hardware systick timer.
 *
 * http://www.freertos.org/RTOS-software-timer.html
 */
SoftwareTimer blinkTimer;

void setup()
{
  Serial.begin(115200);
  Bluefruit.begin();          // Sleep functions need the softdevice to be active.
  sd_power_mode_set(NRF_POWER_MODE_LOWPWR); 
  pinMode(LED_BUILTIN, OUTPUT);  // initialize digital pin LED_BUILTIN as an output.
  blinkTimer.begin(1000, blink_timer_callback);  // Configure the timer with 1000 ms interval, with our callback
  blinkTimer.start();  // Start the timer

  suspendLoop(); // Suspend Loop() to save power, since we didn't have any code there
}

void loop()
{
  // do nothing here , loop is already suspended, CPU will not run loop() at all
}

/**
 * Software Timer callback is invoked via a built-in FreeRTOS thread with
 * minimal stack size. Therefore it should be as simple as possible. If
 * a periodically heavy task is needed, please use Scheduler.startLoop() to
 * create a dedicated task for it.
 *
 * More information http://www.freertos.org/RTOS-software-timer.html
 */
void blink_timer_callback(TimerHandle_t xTimerID)
{
  // freeRTOS timer ID, ignored if not used
  (void) xTimerID;
  Serial.print("timer callback at - ");
  Serial.println(millis());
  digitalToggle(LED_BUILTIN);
  sd_app_evt_wait(); // puts the nrf52 to sleep when there is nothing to do
}

23µA when the LED is off.
However, if you turn the QSPIFlash Off, I measured 4.2µA like with my script.

[AdamM68]

in short …so far I learned that :

• in deep sleep (power off) You can not wake up the device using timer .
• in power on sleep ( sd_app_evt_wait() ) You can use timers to wake up the device

… The only way to wake up the nRF is with one of a few specific external wakeup signals (GPIO, LPCOMP, NFC or pin reset). A wakeup from system off is always in form of a reset…

[Jimmy]

Thank you, Adam. You are right, it is not possible to use the time in “deep sleep” mode. However, using the "sd_app_evt_wait() " function, I could achieve a low power consumption, which is very suitable for my application.

Thank you very much for the contributions!

[PJ_Glasso]

Jimmy ,
Yes I wanted also to use a timer, would be preferred. However NOT available to or in both Board versions and weather or not the BLE and IMU function properly with sd_power_mode_set(NRF_POWER_MODE_LOWPWR); functions AFAIK, other views are welcome.
I’m pretty sure that’s why SEEED Licensing put the RTC on the expansion board. RTC interrupt WAY more reliable. and there original If you want to call it “engineering” choices where the wrong ones. Mbed, no mbed either way it’s “HALF” a loaf. just like the battery reading shenanigans’
On my board I added the RTC just to overcome and enhance the capabilities.

Rev 2.0 board all mostly SMD parts, NO RTC (found out about NO low power support with BLE and IMU, or reliable battery reading.

Rev 3.1 with RTC , Serial1 port and a display interface connector and a buzzer.

HTH
GL

[AdamM68]

wow ! looks great

Do You know any other nrf52840 boards that are “full” like yours ? … and can support proper system-on sleep with BLE use ?

Reading your post I understand that I will not get proper system-on sleep during BLE using ?
Maybe it is a matter of what kind of system-on sleep I will use … thete are a few options of the mode :

[daCoder]

I published a sketch and a rewritten arduino interrupt module under this topic Getting lower power consumption on Seeed XIAO nRF52840. The sketch demonstrates an arduino loop() that operates at 3uA with gpio interrupts and no delay() calls using system_on sleep mode. It also demonstrates system_off and wake from system off.

[AdamM68]

is this board for “xiao nrf52840” on the market ?

[mogul]

this one?

Seeed Studio XIAO nRF52840 - Supports Arduino / CircuitPython- Bluetooth5.0...

[hardhik]

I am working on a project which uses Li-Po 300mAH battery for powering up my seeed studio xiao nrf52840 ble sense board. I want to implement sleep mode in it so that my power consumption decreases, but it is important that my data stored is not lost when the device is in sleep mode as I will transmit it using ble later. It would be better if I can wake up my device from sleep mode when a external button is pressed. I have followed above code but unfortunately my board is getting bricked. Kindly let me know any resources to follow or look into.

Any help is appreciated. Thanks in advance

[AdamM68]

no.
I ask if this one is on the market

@PJ_Glasso

Rev 3.1 with RTC , Serial1 port and a display interface connector and a buzzer.

[AdamM68]

…what do You mean bricked ?
is it destroyed ?
… after deep sleep = “power off sleep” the device is waking up like after reset.
To keep some data on the device I think You should use “power_on sleep”

Look here

Getting lower power consumption on Seeed XIAO nRF52840

Optimizing Power On nrf52 Designs This Nordic page might be useful to solve power issues. This is what clued me in on the interrupt issue.

[hardhik]

Hey Adam,
Thanks for the reply
My serial port was not able to read the board, but thankfully I was able to reupload the bootloader hex file to reset the board.

Coming to power_on sleep I will test it out and get back to you with any update.

[PJ_Glasso]

LoL, No… its a roll your own.
I made it to address some of the poor design decisions by seeed imo.

Interrupts, rtc etc. I may mod it again to address the battery reading short-fall of the designs software hooliganism.

JLPCB is your friend.
GL ,PJ.

[AdamM68]

@PJ_Glasso

JLPCB

JLCPCB …never used this …long way ahead of me

[hardhik]

@AdamM68

“power_on sleep”

Update: To use power_on sleep I need to use softdevice which uses bluefruit library, but bluefruit library is compatible with v.1.0.0 for board manager. This version is toggling with the IMU sensor on the board. Can I have any other way to not use softdevice and put the device in system on sleep mode to save the data. Something similar to NRF_POWER->SYSTEMOFF = 1 command.

Thanks in Advance

[PJ_Glasso]

Hmmm, Not that I’m aware of maybe someone else can comment, I would think the QSPI flash is where you can store the data before a sleep and system reset as the only wakeup method? I use only Mbed afaik it’s the only way to get BLE and IMU together and patch or hack Battery reading and Sleep mode lameness.
I’m looking toward getting RTC low power INT generated and save data in Flash for my next push. The BLE IMU data notify and connectivity to the MIT AI2 is very good and reliable for me. It’s battery reading and sleep ALL or nothing that SUCK. Nordic has it figured out and so does adafruit, SEEED ?

HTH
GL
PJ

[hardhik]

Hey @PJ_Glasso ,
Thanks for a lead.

Tired to first test using a basic QSPI flash code present in SEEED_nRF52840_QSPI/QSPI_New.ino at main · PMCheetham/SEEED_nRF52840_QSPI · GitHub , got the expected output but unfortunately whenever I try to use flash of the seeed studio board it is getting bricked meaning I can’t detect the board on serial port anymore.

So i guess it’s a risk to toggle with flash memory of the board. Any other solutions or resources by yourself or anyone else is highly appreciated.

[NRF52]

Hi!
I wrote a very simple code to check the current in sleep mode, measured the current - 8 µa.
According to the manufacturer’s specification, you can get less current.
How to do this ?
Who was able to get a current of less than 8 µA ?

my test code:
void setup()
{
delay(10000);
NRF_POWER->SYSTEMOFF = 1;
}

void loop()
{

}

[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.