What can prevent nRF52840 board to go into deep sleep mode?

[Aduka_27]

Hi guys, 

Using the PPK 2 board I have noticed that sometimes my device does not go into deep sleep mode between two tasks. I had to implement a lot of flash operations using Mesh configuration, saving some data before and after each task execution. Also, I added some parts with clocks and ADC. I have seen that sometimes, not very often, something prevent my device to go in the deep sleep state between two tasks, and now I am trying to find the possible answer for that. The timer is used to call a function, and ADC to measure the voltage before each task execution. I also send you two graphs which can maybe help you to understand my issue. I hope that somebody has a logical explanation for this behavior. 

Br,

Adnan. 

Prevent the deep sleep mode: 

Normal execution: 

[koniho]

Have you reviewed the chip errata's? There are quite a number of them that can intermittently prevent the chip from going to sleep. I would review the nrf52840 errata and associated SDK release notes to determine which workarounds you may need to implement.

[Aduka_27]

No, I have not, but for sure I will try to find the answer there. I am using nRF52840 (PCA10056 2.0.1), and there are 5 different revisions on the Nordic website. Also, I am using nRF5 SDK for Mesh v.4.2.0. Is there any specific website or correlation between the revision of board and version of development kit?? 

Br,

Adnan.

[JONATHAN LL]

Link to errata: https://infocenter.nordicsemi.com/topic/struct_nrf52/struct/nrf52840_errata.html?cp=4_0_1 

Mesh v4.2.0: https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.meshsdk.v4.2.0/md_RELEASE_NOTES.html?cp=8_6_0_0_0 

We don't have a list of the that shows what issues is related to what SDK and HW combination. 

Regards,
Jonathan