How to optimize the power consumption of a simple Broadcaster ?

[Sylvain]

Hello  Nordic support team,

I broadcast data each 1 second and I use the following function (as used in many examples) to manage the power consumption.

while (1){
    power_manage();
}

Unfortunately, I measure a consumption of 3mA between each data packet transmitted. I expected that the sd_app_evt_wait() function manage correctly the power, but apparently not.

Do I need to activate the RTC or LFCLK between the packet emission ? If I try to do that, it the data will be yet transmitted ?

In summary, I would like to go in system ON mode between two radio transmission and then get a wake up on the broadcast transmission event.

Kind regards,
Sylvain.

Specifications:
- nRF52840
- SDK 14.2
- SoftDevice S140 5.0
- Segger Embedded Studio

[cbd]

Which processor and SDK are you using?

[Sylvain]

edited on the first post.

[Einar Thorsrud]

Hi,

You do not need to do anything other than calling sd_app_evt_wait() in the main loop, which I assume you do. In that case, the SoftDevice will only keep the 32 kHz clock and RTC active, so you should see a current consumption of approximately 2 μA. However, the SoftDevice will not disable any clocks or peripherals the application has enabled, so if you use other peripherals or have UART logging enabled, you will see a much higher current consumption. Still 3 mA is a bit high, though. Do you have any other components on your PCB that could cause a high current consumption, such as a LED?

[Sylvain]

Hi Einar,

For now,  I use the PCA10056 and for the current measurement I put the board in nRF only mode. In debug mode, I see that all the ram are activated maybe it's the problem.

I haven't activated any other peripheral ... I'm asking myself if the softdevice power management works in my code

[Einar Thorsrud]

The sd_app_evt_wait() function is quite simple, so I do not see how it can fail. However, the state of the device is of great importance. The current consumption could indicate that the CPU is active, so perhaps something causes immediate and repeated wake up after you have called sd_app_evt_wait(). Can you upload your code here?