SPIM current consumption is large

[talby]

Hi

I am evaluating nrf52832.
I implemented SPIM with reference to nRF5_SDK17.1.0.
It is working correctly, but the operating current during transfer is high.
The average current is about 1.6mA.
The expected value is about the sum of SPIM's Run current for SPIM, 2 Mbps 50uA and HFINT Run Current 60uA.
Does anyone know the cause?
Is it possible to improve it?

best regards!

[Jared]

Hi,

Average run current should be around 1µA. Are you only using the SPIM peripheral? How are you measuring the current? Did you remember to enable the DC/DC?

Is it possible to improve it?

If you want to get better average current then it would be smart to increase the frequency that the SPIM runs at, so that you quicker finish the transmission of data and can go to sleep longer,

regards

Jared 

[talby]

Thank you for your reply.

I am measuring by inserting an ammeter into the 3.3V power line.

With the same H/W, BLE advertising has the expected waveform. (attached)

I am using DC/DC. When DC/DC is turned off, the current increases.

Soft devices are valid for devices other than SPIM.

app_timer.c is also valid.

However, when not using SPI, it is less than 4uA, which is as expected.

I am using nrf_drv_spi.c as is.

best regards!

[Jared]

Hi,

Do you have logging enabled? Could you show me your code?

When you enable the SPIM you will have EasyDMA current + HFCLOCK will also be active during the transaction. 

regards

Jared

[talby]

Thank you for your reply.

No, Logging is disabled.

Sorry, we cannot release the source code.

Thank you for your cooperation.

best regards.

[Jared]

I see, well 1.6 mA is about the expected current when you run SPIM as the EasyDMA current itself is around 1 - 1.2 mA.

I think what you measure seems reasonable. To save power you need to disable the SPIM and go IDLE sleep after you've done with transaction. 

regards

Jared