Power Management with NRF52833

[Thishon]

I am using NRF52833 Microcontroller to read data from the PCR based radar sensor. I am using NRF Connect SDK Version 2.6.1. I need help regarding reducing the power consumption. My Controller is consuming a current average of 40mA for one cycle (6s duration) whenever fetching the data from the sensor which is huge in terms as I am planning to power the device using battery. Power management is enabled already.

 This is my prj.conf contents:

# # Power Management

CONFIG_PM=y

CONFIG_PM_DEVICE=y

CONFIG_PM_DEVICE_RUNTIME=y

This is the inclusion I have done on my main src file

#include <zephyr/pm/pm.h>

I disabled all other unused pheripherals like uart, spi and i2c from the device tree. but still power consumption is high.

k_msleep(SLEEP_TIME_MS);

 

When using the above function, the device enters sleep mode and current consumption is limited but when fetching the data using my data_fetch() function.

I have used the power management function in the data_fetch() function

#ifdef CONFIG_PM_DEVICE

    pm_device_action_run(spi_dev, PM_DEVICE_ACTION_RESUME);

#endif

The current consumption is still more. Are there any solutions to reduce power consumption.

[Vidar Berg]

Hello,

What is the run current of the sensor itself, and what is the system idle current between samples? I wouldn't expect the system run current for the nRF52833 to be much higher than 4–5 mA, even if both the CPU and SPIM remain active throughout the sampling period.

Best regards,

Vidar

[Thishon]

As you can see the ideal current aerage for 10 s interval in sleep mode is 197uA

The average current consumption for one data read cycle is 43mA

[Vidar Berg]

As I indicated in my previous reply, the nRF52840 should not be able to draw this much current by itself. This is why I asked about the run current for your radar sensor.

[Thishon]

The radar sensor module I am using is an ultra-low power consumption package. According to the data sheet the average power consumption 0.2 mW at 0.1 Hz update rate, 3 mW at 10 Hz update rate and 20 mW at 100 Hz update rate with the supply voltage of 1.8V and current can reach upto the maximum of 100mA

I do know how to measure for the current drawn by the sensor as I am using a customized board.

[Vidar Berg]

It sounds like you may want to experiment with different sampling rates or other sensor configurations since the current consumption is primarily from the sensor and not the MCU.

[Thishon]

Yes. Working on that. Thanks for your insights

[Thishon]

The radar sensor which I was using has an enable and power enable pin for low power consumption modes. On disabling the enable pin and power enable pin during sleep mode and then enabling them when fetching data from the sensor I was able to reduce the power consumption.

Addition to that BLE was consuming some power when Advertising. Disabled BLE when entering sleep mode.

Which improved my power ratings and consumed <1.5uA when on sleep mode and 19mA for the data fetching and advertising cycle.