effect of connection interval on peripheral power consumption

[Eliot Stock]

I have a custom board using the nRF51822 as a peripheral with the S110 SoftDevice. The centrals are mobile apps, both Android and iOS. The device spends a lot of time in a BLE connection and I'd like to optimise for power consumption.

Attached are screenshots of two Wireshark logs. In one, the min/max connection interval are 0.5s/1.0s. In the other, they're 4.0s/4.0s. I've measured the current at 3.7V in both cases and seen no difference: whichever min and max connection interval I specify, I still use 0.8mA. Shouldn't the slower connection interval use less current? Can we be sure this is really the interval in use?

screenshot_wireshark_slow_conn.png

screenshot_wireshark_fast_conn.png

[John]

I suspect that your current consumption isn't due to the connection intervals. 0.8mA is about what you would expect to see if a peripheral that used the 1V2 regulator and the 16MHz oscillator was enabled. I'd check to see what peripherals you have enabled vs. table 28 (Section 8.3) of the nRF51822 product specification.

[Eliot Stock]

From table 8.3 I'm only using the radio directly.