power efficiency in transferring data

[Reza papi]

hello all,

I am trying to find the best power efficiency to transferring a pack of data(30 byte each time) from one nrf52 to another nrf52. I have a 80 uA in average power budget. so, what is your suggestion for me about this project?

[haakonsh]

How often do you need to send it?
What are your range requirements?

[Reza papi]

I want to send data every 5-10 seconds.actually the range has not been decided but consider 10 m. 

[haakonsh]

Then you have quite a lot of options actually. 

I suggest you create a full BLE connection with 5-10 seconds connection interval, and use 2mbps PHY. At 2mbps you reduce the on-air time of the radio and thus its current consumption. 

I also suggest that you use Data Length Extention with an LL MTU size of at least 30 bytes. This will ensure that your 30byte payload is transmitted in a single packet instead of multiple ones, thus reducing the on-air time of the radio. The standard LL MTU size is 27 bytes

You can optionally reduce the tx power if you find that you have more range than required, this will reduce the current consumption somewhat. 

I suggest you use and external LF crystal instead of the internal LF RC oscillator as you will likely spend a lot of time in sleep and the LF crystal has a lower current consumption than the RC oscillator. 

The DCDC converter will also reduce the current consumption a fair bit. 

I don't know what else you will be doing with the microctontroller, but the BLE connection whould only require ~3.5µA with your requirements. Though you will be using a bit more current to establish a connection.

You can play around with the Online Power Profiler in order to optimize further: https://devzone.nordicsemi.com/nordic/power/w/opp/2/online-power-profiler-for-bluetooth-le 

[Reza papi]

Thank you very much for all these information. Do you suggest any sdk examples which match to create this full BLE connection as you said? 

[haakonsh]

Check out the UART/Serial Port Emulation over BLE example, you'll have both central and peripheral examples.

[Reza papi]

Thank you, haakonsh. I will go through this example.