Guidance Needed for Measuring nRF52805 Current Consumption (Sleep, TX, RX Modes)

[PKG]

Hello,

I need to measure current consumption on the nRF52805 in sleep, TX, and RX modes. Which sample applications are recommended for each of these measurements? Additionally, please advise if there are any specific considerations or precautions I should keep in mind to ensure accurate current measurements.

Thanks,

PKG

[PKG]

Hi Samruddhi,

Thanks for sharing the link. I’ve made some progress on my side. I’m measuring the sleep current with the system in System OFF mode [sample: System Off ] , and I’m seeing about 0.173 µA. However, the link shows that the expected sleep current for System OFF, no RAM retention, wake on reset is around 0.3 µA.

I’m not sure whether my code is currently using RAM retention or not. How can I configure the system to ensure RAM retention is disabled?

Also, I’m not certain whether the sample I’m using is configured for DCDC or LDO mode. How can I change this configuration in the code?

Sample :

.. zephyr:code-sample:: nrf_system_off
:name: System Off
:relevant-api: sys_poweroff subsys_pm_device

Use deep sleep on Nordic platforms.

My measurement.

Thanks,

PKG

[Samruddhi Jadhav]

Hi Praveen,

Here are some points and samples I would suggest you to take a look at:

1) For System ON Idle Sleep: It is like using Hello World with CONFIG_SERIAL disabled. 

2) System OFF Sleep: Take a look at: https://github.com/nrfconnect/sdk-zephyr/tree/ncs-v3.2.3/samples/boards/nordic/system_off

3) For TX, Take a look at: https://github.com/nrfconnect/sdk-zephyr/blob/ncs-v3.2.3/samples/bluetooth/beacon/src/main.c#L57-L58 (Here, remember to remove scan response and zoom in on each of the events)

4) For RX, Take a look at: https://github.com/nrfconnect/sdk-zephyr/tree/ncs-v3.2.3/samples/bluetooth/observer (Here, make sure that the scanning is passive. Also, 100% duty cycle)

Let me know if you have any further questions.

Best Regards,

Samruddhi

[PKG]

Hi Samrudhi,

For the sleep current, I was using the same sample that you shared.  https://github.com/nrfconnect/sdk-zephyr/tree/ncs-v3.2.3/samples/boards/nordic/system_off

The attached waveform was recorded during sleep mode. I’d like to understand what the larger spikes represent, as well as the smaller spikes that appear between them.

Also, do I need to modify any code for no RAM retention?

How to change the configuration from LDO to DCDC mode?

Thanks,

PKG

[Samruddhi Jadhav]

Hi Praveen,

I am looking into this and need some more time. Please note that there may be some delay in response time due to Easter. I will get back to you with an update by early next week. 

Best Regards,

Samruddhi

[PKG]

Hi Samruddhi,

Could you help clarify how to switch the configuration from LDO mode to DCDC mode? I’ve tried several approaches, but none of them seem to work on my setup.

Thanks,

PG

[Samruddhi Jadhav]

Hi Praveen,

Apologies for the delay. LDO is used for ultra low power on nRF52 devices. According to what is most efficient, the system will automatically switch mode and that shouldn't cause a difference in result. For reference, you can take a look: Power - Power supply.  In System OFF, RAM retention is not enabled. This is by default. Take a look at fields C-D in: POWER — Power supply. You mentioned observing 0.173 µA. This is quite low but it can also be due to certain factors affecting the measurement such as chip-to-chip variances and temperature. 

Best Regards,

Samruddhi