Reading NRF52840 DK battery level

RE: Reading NRF52840 DK battery level

Jørgen Holmefjord — Thu, 22 Feb 2024 14:19:32 GMT

Hi,

Yes, please create a new ticket for these questions, as they are not related to the topic of this thread.

Best regards,
Jørgen

RE: Reading NRF52840 DK battery level

Adrian1504 — Thu, 22 Feb 2024 11:55:17 GMT

Hi Jørgen,

Thank you so much for your answer.

I will be trying this, but some other doubts came while working. I guess I will have to make another ticket for this:

How can i test the data transmission rate of the nrf52840?

Which is the best way of sending the data read from a sensor?

RE: Reading NRF52840 DK battery level

Jørgen Holmefjord — Fri, 09 Feb 2024 15:49:12 GMT

Hi Adrian,

[quote user="Adrian1504"]Is it in here where the Proximity application will be? Because with my current version I don't seem to find the sample. [/quote]

No, the proximity application is only available in nRF5 SDK (our old SDK in maintenance mode). If you are already using nRF Connect SDK (the new SDK variant that will support new features) you should stick with this and not try to use the examples from nRF5 SDK.

In nRF Connect SDK, I'm not aware of any simple example showing both battery measurements and the BLE battery service, but there is a battery sample that you can use as a starting point. You need to create an overlay file for the board you are using (for instance "nrf52840dk_nrf52840.overlay" placed in the root of the sample directory) and fill it with the "zephyr,user" node as described in the sample readme. By default, this sample does not support VDDHDIV5, only the standard VDD input, but you should be able to change this to SAADC_CH_PSELP_PSELP_VDDHDIV5 in the code. If you want to use BAS to transfer the battery level over BLE, it is quite simple to use this service in nRF Connect SDK, see for instance how it is done in the Peripheral HIDS: Keyboard sample (with dummy battery levels).

Best regards,
Jørgen

RE: Reading NRF52840 DK battery level

Adrian1504 — Thu, 08 Feb 2024 11:55:59 GMT

Hi Jørgen,

Thank you for your answer. I have the nRF Connect SDK v2.4.1, now that I entered the toolchain manager I see that there is a v2.5.2, Is it in here where the Proximity application will be? Because with my current version I don't seem to find the sample.

For measuring with the SAADC it means I have to read from

VDDHDIV5

0x0D

VDDH/5

It would be reading the analog value?

Sorry for the questions, I am literally starting in this embedded software world.

Thank you,

Adrian Lopez

RE: Reading NRF52840 DK battery level

Jørgen Holmefjord — Mon, 05 Feb 2024 15:02:14 GMT

Hi,

Which SDK variant are you using? Bluetooth BAS service does not sample battery level on its own, this needs to be handled in the application and supplied to the battery service to update the battery level over BLE.

In nRF5 SDK, there is an example, Proximity Application, that implements BAS along with actual battery level reading from the VDD input of the chip.

[quote user=""]Also, I saw some questions in the forum, from 3 years ago, and it is mentioned that it can not be read directly in the DK, but we need to do a voltage divisor to bring the voltage from the battery to a gpio port.[/quote]

The nRF52840 SAADC supports direct sampling of both VDD and VDDH/5 inputs, as mentioned in the input pin configuration register. If you are powering the chip in normal voltage mode directly from a small battery (for instance a 3V coin cell) or through high-voltage mode directly from a battery (for instance a 3.7V Li-Po battery), you should be able to measure battery voltage without any external circuitry. You will need to create a battery profile for the battery in use in your application, to convert the voltage to battery level.

Best regards,
Jørgen