Hello,
I could use some guidance on where to look for a power draw that I am not understanding. I am not a hardware engineer but have been tasked with completing firmware for a custom board based on the nRF52832 chip. The system is built using SDK 16.0.0 with SD S132 v7.3.0. I am puzzled by the following power changes:
When the board boots and initializes the system, the power draw jumps from around 7mA to 10+mA after a call to sd_radio_request(). The power consumption remains at 10+mA until I begin advertising at which point it rises to around 11mA. Once I connect to the device, the power drops back down to 10+mA. Once connected, I write to a characteristic to begin sampling the ADC. The samples are acquired at 1KHz, buffered, and sent via BLE notification back to the central. During this time, the power consumption drops to 5mA (drops by 50%). When I disconnect, sampling stops. What is baffling to me is that the power draw remains at ~4.5mA post disconnect. The state of the device, at least from the top level firmware perspective, is the same as during the initial power-on scenario when the device was drawing 10+mA. What could possibly be occurring during and post connection to cause the sudden power savings?
The code was originally derived from the time-sync demo (https://github.com/nordic-auko/nRF5-ble-timesync-demo) and expanded from there to add ADC acquisition based on timers and PPI events.
I am not necessarily asking for solutions; but areas of possible SoftDevice / BLE configuration that could account for such a change in power consumption pre-initial connection, connection, and post connection. Once I am past the initial connection, the power draw never rises above 5mA. I see the same behavior on my PCA10040 DK board as well only the power consumption goes from 14mA at initial run down to ~8mA while acquiring and sending, and then down to ~1.2mA when disconnected.
Thanks for any advice and/or direction to take in my investigation.
-Mike
