Description
Espruino implements some power saving on Bluetooth connections:
In 'high power' 7.5ms interval mode it draws around 600uA, but in low power 200ms mode it's 40uA
- If the connection is idle for ~2 minutes it drops into Low Power mode
- If there are two writes/reads within 2s (10 connection intervals) of each other , it enters high power mode
Code:
Espruino/targets/nrf5x/bluetooth.c
Lines 721 to 731 in 38bcf2c
Personally I feel like this could be improved, since calling jsble_peripheral_activity twice is enough to go to a high MTU. Just a single read+write in one connection interval could do it now.
There are some specific use cases:
- When typing in the REPL we'll have a data coming in to the Bangle in small packets, in quick succession - we want to enter high speed mode when there's apprecialble lag (but the odd character or two shouldn't trigger it)
- A Puck.js might be used as a sensor/HID button. Someone presses the button and maybe a press+release event are sent - we don't want to enter high power mode for the next 2 minutes
- For Bangle.js with a Gadgetbridge connection, we send health info every 10 minutes, and also receive notifications. We'd hope that neither of those would push us into a high speed connection mode (especially using big MTUs) but I think they could be.
Maybe it makes sense to have a rolling list of connection intervals/whether they are busy or not, and then maybe if 3 of the last 5 are busy we go into high power mode? Also maybe drop back down after 1 minute?