nRF52832 not able to go to low power mode

[SK]

Hi All,

I am developing an application in which i am interfacing the nRF52832 with an ADC via SPI. 

I am doing channel multiplexing (2 channels) such that when i get data from 2 sensors, i am putting the micro in low power mode for 2 seconds and the process repeats. 

Now, when i am just using single channel,  micro goes to low power mode as programmed. But, with 2 channels, it is not able to. Any idea on what can be causing the micro to wake up? For SPI, i am using SPI transaction manager.

Any leads will be useful. Thank you!

[Jørgen Holmefjord]

Hi,

Can you please post some code showing how you interface the SPI devices, and how you put the device into low power mode?

Uploading your entire project would also help to debug this issue.

Best regards,
Jørgen

[Jørgen Holmefjord]

Have you debugged the application to see if it is stuck in a loop somewhere? It looks like there is some cases in you application where power_manage()/sd_app_evt_wait() will not be called.

[SK]

Hi, 

Yes i did. Function change_mux_channel is the one causing the issue. Once i try to change ADC channel, it is not going to low power. Any thoughts if its related to how i am handling SPI? 

[Jørgen Holmefjord]

What exactly do you mean by "change_mux_channel is the one causing the issue"? Do the application get stuck in this function? If it does, on which exact line is is stuck? If not, do it enter the other states in your application where power_manage() is called after change_mux_channel is done?

[SK]

It doesn't get stuck anywhere actually.

change_mux_channel() is just sending commands to configure registers on ADC for channel switching. 

This is how the flow is supposed to be working: 

1. gets data from pH channel (default configuration)

2. Change channel to configure for Temperature

3. Go to low power mode till timer 2 is not expired 

4. gets data from temperature channel 

5. Change channel to configure for pH 

6. go to low power mode till timer 2 expires 

7. repeat 1-6

During this channel switching, problem lies. There is some event or INTR thats keeping it up and now allowing to go to low power mode.

[Jørgen Holmefjord]

Did you add the use of floats at the same time you added the change_mux_channel function? Have you added the workaround described in this errata to your project?

[SK]

Thanks, i included that in the project now. But it is throwing a compiler error 

I followed this forum afterwards to solve the issue: https://devzone.nordicsemi.com/f/nordic-q-a/29174/adding-arm-math-library-to-segger-s-nrf52-ble-projects---check-__fpu_present-compile-error

But, issue still remains. Could you help me resolve this issue as well? 

[SK]

Thank you, this worked. Error above that i was getting was because of usage of wrong function names (SILLY!!!)