RE: nrf sleep without losing connection, (Power efficiency)

Stian Røed Hafskjold — Thu, 10 Nov 2016 16:01:58 GMT

I assume that you are talking about System OFF mode when you say sleep mode.

No, the connection requires the chip to be running. However, you can keep the chip in System ON IDLE mode (consumes about 4uA) most of the time and set the connection interval to 4 seconds (maximum interval) to keep the connection alive. This would not require much current.
The connection will be lost. You could theoretically make the phone auto-connect to your device if you create your own app, but that would require the phone to be scanning all the time while it's not in connection, and that would consume a lot of current. Also, the nRF51 must be advertising.
When the device resumes from System OFF most of the peripheral registers are erased and need to be initialized again. You can turn on RAM retention on some of the RAM blocks to retain data while in system OFF, and then, when you wake up, you can check if the reset reason was "System OFF" (RESETREAS register), and then choose to not initialize the data already stored in RAM. What code do you have that you think you would not need to run when the chip starts up?
No, when in System OFF the chip is not running, and the Softdevice with BLE is definitely not running.