Abnormal power consumption with NRF9160 when CONFIG_SHELL_BACKEND_RTT=y is enabled

[Leo]

hi,

   I am using nrf9160+NCS v2.6.1.When the CONFIG_SHELL_BACKEND_RTT feature is enabled, the power consumption increases by 80uA. After investigation, I found that the default value of CONFIG_SHELL_RTT_RX_POLL_PERIOD is 10ms, and reducing it to 500ms lowers the power consumption. I understand that increasing the CONFIG_SHELL_RTT_RX_POLL_PERIOD can reduce power consumption. However, on the nRF52840, enabling CONFIG_SHELL_BACKEND_RTT with CONFIG_SHELL_RTT_RX_POLL_PERIOD = 10ms does not cause abnormal power consumption. What is the reason behind this difference?

[dejans]

Hi,

When the CONFIG_SHELL_BACKEND_RTT feature is enabled, the power consumption increases by 80uA.

What is power consumption when CONFIG_SHELL_BACKEND_RTT is disabled/enabled?

I found that the default value of CONFIG_SHELL_RTT_RX_POLL_PERIOD is 10ms, and reducing it to 500ms lowers the power consumption.

Did you mean reducing poll period to 500 us? How much does this reduce power consumption? What are initial and lowered values for power consumption?

However, on the nRF52840, enabling CONFIG_SHELL_BACKEND_RTT with CONFIG_SHELL_RTT_RX_POLL_PERIOD = 10ms does not cause abnormal power consumption.

What are power consumption values which you observed when using nrf52840 with and without CONFIG_SHELL_BACKEND_RTT?

Best regards,
Dejan

[Leo]

1.For the nRF9160, when CONFIG_SHELL_BACKEND_RTT is disabled, the power consumption is around 40µA, but when CONFIG_SHELL_BACKEND_RTT is enabled, the power consumption increases to approximately 120µA.

2.For the nRF9160, when CONFIG_SHELL_RTT_RX_POLL_PERIOD is set to 10 milliseconds, the power consumption is around 120µA. However, when the CONFIG_SHELL_RTT_RX_POLL_PERIOD is set to 500 milliseconds, the power consumption decreases to approximately 40µA.

3.For the nRF52840,When CONFIG_SHELL_BACKEND_RTT is either enabled or disabled, the power consumption is in the range of around 30 to 40µA.

[dejans]

Hi,

There is a guide on power optimization in the documentation. For example, have you disabled all peripherals and serial logging?

Can you provide more information about your application on nrf52840 and nf9160?

Is it that you are not concerned with power consumption values but only with the difference between the values on nrf52840 and nrf9160 with regard to mentioned Kconfig options? Can you elaborate on this?

Best regards,
Dejan