hold a continuous connection

[Gil]

Hi,

I am programming nRF52840 dev kit (SDK16) as a peripheral with S140. Smartphone is central.

data needs to be transferred between both. 

I need the dev kit to consume as less power as possible.

My question is: 

1. If i use a continuous connection between peripheral and central, can connect more than a single centrals to this peripheral? If yes, what's the limit?

2. which option has less power consumption in the peripheral: is it a continuous connection or is it an advertising (no connection)?

Thanks,

Gil

[Karl Ylvisaker]

Hello Gil,

data needs to be transferred between both. 

How much and how often will the data need to be transferred? What security / guarantee for packet reception is required?

1. If i use a continuous connection between peripheral and central, can connect more than a single centrals to this peripheral? If yes, what's the limit?

Yes. Have you seen the experimental BLE Multiperipheral example? It demonstrates exactly this. 
The maximal limit for concurrent connection for the S140 is 20, but this will depend on your chosen connection parameters.

2. which option has less power consumption in the peripheral: is it a continuous connection or is it an advertising (no connection)?

This depends on your chosen connection parameters. To reduce power consumption you would like to limit your active radio time. So, for example, if you had a connection interval of 7.5 ms against an advertising interval of 100 ms, you would use less radio time(and thus less power) on the advertising. However, the range of possible connection intervals is larger than possible advertising intervals. You may also make use of the slave-latency feature, to avoid sending empty packets from the peripheral, which will also decrease power consumption in the event that there is not data that needs transmitting at the next connection interval(s).
You can see the range of the different connection parameters here. You will also need to ensure that your peripheral device supports the chosen connection parameters.
To play around with the different connection parameters and see how they affect your active radio time and current consumption, I recommend taking a look at the Online Power Profiler. Keep in mind that the online power profiler does not give accurate estimates of application's power consumption, only the radio's power consumption.


Best regards.
Karl