How to put nrf52832 in sleep mode?

[swetha Paladugu]

Hi,

I am using nrf52832 DK.

SDK 17.0.2 softdevice S132.

I am using freertos and running nrf52832 as a peripheral.

I want to put nrf52832 in sleep mode.

I am new to this Sleep concepts. Firstly what are the different sleep modes available and how to use them in the application?

My requirement is, I want to keep the nrf52832 in ultra deep sleep to consume power as less as possible. But it should be always advertising and nrf52832 should wake up for any gpio interrupt.

How to do this? Is there any example project available? Can anyone help me to achieve my requirement? 

[Simonr]

In the nRF52832 product specification the various sleep modes are mentioned under the current consumption scenarios labeled as "Ultra-low power". In general, there are two "main" sleep modes. System ON (when the CPU is idle in its least power consuming state) and system OFF (when the CPU shuts off completely). There are pros and cons to both of these. The system ON mode will consume somewhat more current than system OFF mode but will be able to keep I.E. a timer running so you can wake it up after X amount of time. System OFF mode will provide the absolute lowest power consumption, but will require an external source to wake it up, like a button or NFC field for instance.

As for the "always advertising" part of your question, the radio peripheral will be off when the CPU is asleep, as it is consuming quite a lot of current by itself, so this won't be possible. You can make it wake up and advertise for a set amount of time each time it receives a GPIO interrupt, but it won't be advertising while sleeping. 

Check out the sleep_mode_enter() function in our SDK (present in most example projects) for system OFF mode sleep mode, and idle_state_handle() function in our SDK (present in most example projects) for the system ON mode sleep mode.

Best regards,

Simon

[swetha Paladugu]

Hi,

My application needs the BLE to be always advertising, so that my central device can connect to it at any point of the time and send data.

I cannot wake up with a gpio interrupt and advertise for a certain time as u suggested.

So there is no way i can keep my device in low power mode?

Thanks,

Swetha.