ANT Forum

Hello,

I'm trying to determine exactly how low power mode work when SoftDevice is in use. I've read through the nRF51 Series Reference manual, but it's not quite clear on what is still running in low power mode. I've also gone through the SoftDevice specifications which again is brief and reiterates that power level management is managed through the API.

The SoC library API provides the nrf_power_ API() function which can set either the NRF_POWER_MODE_CONSTLAT or NRF_POWER_MODE_LOWPWR.

In my use case, I want to periodically (every 5 seconds) perform channel scanning for one second. In this time I want to pickup any broadcast messages in the area. Is it possible to be in low power mode and do the channel scanning? If I start a channel scan and put the device in low power mode will that just kill the scan?

Are there any additional documents I can refer to for more information?

Any help would be appreciated.

Cheers,
Marko
     

“Is it possible to be in low power mode and do the channel scanning?”

Great question. Yes, you are able to. I ran a quick test and can confirm that I was able to open a continuous scanning channel in both Constant Latency mode and Low Power mode . In both modes I was able to receive broadcast transmissions.

“If I start a channel scan and put the device in low power mode will that just kill the scan?”

No. I ran another test where I placed the device into Constant Latency mode, opened a continuous scanning channel, confirmed I could receive transmissions and then placed the device into Low Power mode. After being placed into Low Power mode, the device continued receiving transmissions on its continuous scanning channel. I then placed the device back into Constant Latency mode and was still able to receive transmissions.

“Are there any additional documents I can refer to for more information?”

Unknown. You will have to contact Nordic to see if any additional documentation exists beside what can be found at:
http://www.nordicsemi.com/eng/Products/ANT/nRF51422

Regarding your use case, will you require transmitting or receiving any other data during the 1 second period where the continuous scanning channel is opened? If so, it is recommended that you use a background scanning channel. Continuous scanning mode uses the entire radio and does not allow the ANT device to send or receive transmissions on any of the other channels. Background scanning allows you to synchronously receive transmissions from other nodes on the same network and frequency while also leaving the other channels open for use.

A comparison between the two modes can be found at:
http://www.thisisant.com/developer/resources/tech-faq/what-is-the-difference-between-a-background-scanning-channel-and-continuous/

For more detailed information about background scanning, please refer to section 8 of the “AN11 ANT Channel Search and Background Scanning Channel” document, available on the Downloads area of the website.
http://www.thisisant.com/developer/resources/downloads/#documents_tab


Cheers,
Chris      

Thanks for the reply, much appreciated.

My device will never need to transmit data, it will always looking for beacon transmissions. I think continuous scanning will be ideal for my use case.

Again thanks for the help

Cheers,
Marko