SPI/SPIS power consumption

[Scarlet]

Hi, I am developing an BLE application using nRF51822.

This question is from my previous question: devzone.nordicsemi.com/.../question-about-adc-power-consumption

For my application, it will communicate with other device through SPIS all the time. Since other device (SPI master) will transmit 256 bytes data uniformly per second, that is, CSN pin will be setting low every 4ms.

As the product specification 8.3 says, SPIS need "HFCLK + 1V2" and this will consume more 1 mA of current.

I want to know about the power consupmtion of SPIS When CSN is high, will the "HFCLK + 1V2" always active and consume 1mA of current?

If yes, is there any suggestion to reduce the power consumption? Thanks.

[Håkon Alseth]

Hi,

The SPIS only requests the 1V2+HFCLK when CSN is asserted. This means that you can go into sleep with a good conscience :-)

I did a quick test with the "spi_slave_example" in the SDK, and confirmed that it's drawing ~2.3 uA when in sleep (w/ NRF_SPIS1->ENABLE set)

Best regards Håkon

[Scarlet]

Thank you so much!! It really helps!!

For my further application, it may connect with another sensor through TWI.

I want to know the more general conclusion: For SPI/SPIS, TWI (communicate with other devices)

Are these peripherals consume more 1 mA of current only when they are working?

That is, these peripherals would consume very low power when they are sleeping (enabled but idle).

Since I've read the GPIOTE configuration has the power consumption problem. (PAN 2.0, 39, GPIOTE: 1V2 + HFCLK are requested always when the GPIOTE task is configured.) I want to make sure the power consumption problem only happens in GPIOTE.

Thanks agein!

[Håkon Alseth]

Hi,

SPI Slave is only active (and requesting 1V2+HFCLK) when CSN is asserted. TWI and SPI master will always request 1V2+HFCLK when it's enabled. You can clear the ENABLE bit in the peripheral to ensure low current consumption.

Best regards Håkon

[Scarlet]

Thank you so much! I will think how to reduce the power while using TWI :)