Low-power for nrf52

[Artur]

Hi,

I am trying to develop low power beacon on nrf52.

Which example should I base on?

I am trying example ble_app_blinky on PCA10040, and I am getting close to 1 mA, but I need something closer to 10uA.

In this example in main loop there is sd_app_evt_wait() so shouldnt it work?

Regards,

Artur

[AndreasF]

Hi.

Try the following steps:

1. Disable the logging by editing the following in sdk_config.h:

// <e> NRF_LOG_ENABLED - nrf_log - Logger
//==========================================================
#ifndef NRF_LOG_ENABLED
#define NRF_LOG_ENABLED 0
#endif

2. Enable the DC/DC regulatorby calling sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE)

3. Increase the advertising interval APP_ADV_INTERVAL

I hope this works for you.

Best regards,

Andreas

[Artur]

Thank You for quick reply but it lowers current to circa 640uA. Not there yet.

sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE) before main loop?

I am using s132 and SDK14.2.0 because I want to do final project on nrf52810. Can SD or SDK be a problem?

[Artur]

I am keep getting results near 700mA. I have been trying beacon and blinky examples.

I disabled log, set dcdc, increased interval etc. I am trying examples on PCA10040 not on my board to exclude hardware mistakes.

Have You got any more hints?

[AndreasF]

Hi.

Can you try this in order to check if there is any hardware faults:

1. Download this file: test.hex

2. Do nrfjprog -e.

3. Program only this .hex file (test.hex)

4. Measure the average.

This is what I got:

About 480 µA average. With only logging disabled.

Best regards,

Andreas

[Artur]

Hi,

2.5mA on average with oscilloscope. Handy multimeter showed results closer to 3mA.

Regards,

Antek

[AndreasF]

Hi again.

Are you sure that your measurement setup is correct?

Have you read the documentation on how to measure with a oscilloscope and a multimeter?

Best regards,

Andreas

[Artur]

Hi,

I may not measure exactly like in documentation but I have two PCBs to check.

I am testing softwares also on my beacon, and when I run my low power nrf51 code on nrf51 beacon I get 5uA between advertising, on beacon with nrf52 and nrf52 code I get 500uA.  

Should I change #define NRF_LOG_BACKEND_UART_ENABLED 1?

Should I do something with FPU unit?

Regards

[AndreasF]

Hi.

If you don't measure like the documentation, then I can't really compare my measurements to yours.

Which chip/DK are you using? Which pins are you using?

You do not need to change the define of NRF_LOG_BACKEND_UART_ENABLE nor do something with FPU unit.

[Artur]

Hi,

About my development PCB, is there possibility to enter low power mode (<10uA) without external oscillator?

Or maybe the problem is that I am using app_timers?

Can I pause my code in debugging and check some registers to be sure that low-power is enabled?

Regards

[Artur]

I am close to success today.

My problem was probably this:

On PCA10040 maybe wrong measurement.

On my PCB with no external clock I was choosing NRF_CLOCK_LF_SRC_SYNTH in Softdevice Clock Source (probably wont go this way into sleep at all). Correct setting is NRF_CLOCK_LF_SRC_RC (file sdk_config.h, line close to 5620) and some other small changes like post here:

devzone.nordicsemi.com/.../change-clock-source-nrf52832-app-beacon-example