Techniques for SD Card power consumption reducing

[ALope.1]

Hello everyone,

I have a complete developed board for audio recording by an attached MEMs microphone at 32KHz and using an SD CARD. Although the microphone is not supposed to be on all the time, there are some periods where it needs a continuous audio recording that is directly stored into an SD Card in real-time (otherwise, there would be no space in memory to save all the audio data).

The system is working with no problems, but now we realize that the system is consuming 5 times more energy than the supposed, due to SD Card presence. We also verify that the consume varies with different SD card models.

There is someone who can give us tips about how we can lead with this problem? We aim to achieve the lowest power system possible.

Some of the solutions that we have been proposing:

• use DMA for SD card recording data
• Add an EEPROM or other external memory which could store audio data allowing less SD card writes per time unit.
• Change SD Card

Any of them could make sense?

Thank you!

[ChahinezC]

Hello @ALope.1​,

Can you please precise the chip you are working with?

We recommend you having a look at STM32 Ultra Low Power MCUs, they might help with your problem, they implement several low-power modes, you can refer to the 4.section of AN4621 to know more about the choice of the one to work with.

Several tips & tricks to minimize power consumption while increasing performance for STM32L4 devices as example are also described in AN4746. 

As for the solutions proposed, the use of the DMA might be the best option as it allows to avoid waking the CPU up for moving the data, that's role of the DMA. It is as well mentioned in the 6.2 section of the AN4746.

Chahinez.