Some questions about power management and advertising

[gercer]

Hello!

I'm currently using a nRF52832 with the SDK15 blinky_app_project and Segger Embedded Studio. What I am aiming to do is program where it goes to sleep after some seconds of advertising and if I press the button it wakes up and start advertising again for a few seconds and go back to sleep after that.

What i have understand so far is that the function sd_ble_gap_adv_start starts the advertising and nrf_pwr_mgmt_run will put the device to sleep mode. 

I have a few questions about this. 

1. If i call adversting_start() the device wakes up to advertise or it stays in sleep mode?

2. when the device is in sleep mode, is it posible to disable everything except one port for the wake up? If possible, how to achieve this? I wanna save as much energy as possible when it's not advertising or connected.

3. How low is the current of the nRF52832 when it is in sleep mode?

 Thank you very much.

[Martin Lesund]

Hi Gercer,

  I would recommend you to look at the "ble_app_uart" example and use that as reference since it is implemented just like you are aiming to program.

If you set #define APP_ADV_DURATION 1000, it will advertise in 10 seconds before it goes to sleep and wake up when you push a button.

 

1. No,you have to wake up the device before you can start to advertise. (Look at "ble_app_uart")

2. When the device is in "System OFF" mode, it will disable everything but not the wake-up source. I recommend you to play around with the Power Management Example.

3. This can be found in the Documentation:

- 0.3 μA at 3 V in System OFF mode
- 0.7 μA at 3 V in System OFF mode with full 64 kB RAM retention
- 1.9 μA at 3 V in System ON mode, no RAM retention, wake on RTC

 

[gercer]

Thanks for the answer!

I was looking at the uart demo and i noticed they use ble_advertising_start instead of sd_ble_gap_adv_start which is used in the ble_app_blinky demo. Could you explain my the main differences between them and which one is recommended?

[Martin Lesund]

Hi Gercer,

ble_advertising_start() is a function for starting advertising, and it is from the Advertising Module.

sd_ble_gap_adv_start() is a Softdevice API call to start advertising.

So if you look into the "ble_advertising_start()" in "ble_advertising.c" you can see that "sd_ble_gap_adv_start()" is actually called inside that function.

> I recommend using the Advertising Module