SPIM power usage

[mosgaard]

Hi,

I have a project with nRF52840 where I uses 3xSPIM. 2 are connected to a real-time-clock and accelerometer. The third is connected to an SD-card.

I realized that the idle power consumption is ~1mA when the SPIM modules is not closed between communication. It seems the HFCLK continues to run.

The RTC and accelerometer is easy to shut down and is only sampled with 20Hz.

However the SD-card cannot be shut down without closing the file-handle and do a reinitialization each time.

I am writing to the sd-card every 20 second and I am unsure if a sd-card can handle being reinitialized so many times (lifetime of product is 10 years).

Are there anyway to shut down the HFCLK or reduce idle power of the SPIM modules or what is the normal way of doing this?

Regards,

Morten

[Kazi Afroza Sultana]

Hello Morten, 

This is from our documentation:

''To ensure lowest possible power consumption when the peripheral is not needed stop and disable SPIM.

The STOP task may not be always needed (the peripheral might already be stopped), but if it is sent, software shall wait until the STOPPED event was received as a response before disabling the peripheral through the ENABLE register.''

Nordic SDK 15.3 and SoftDevice 6.1.1 seems very old. 

You have to rewrite the driver so that SD shuts down in between transfers when it does not need to be used. Have you ever thought of migrate to NCS?