Abrupt increase in the current readings Amidst Logs in Temperature Data Logger after connecting the peripheral while in the Advertising mode.

[Ankush]

Hi,
I am trying to implement a Data Logger using nRF52832. I am using a Temperature Sensor to get the Temp readings(logs) and a Flash Memory to store those logs.
The data logger functions first in the Advertising mode followed by the data logging mode and then Sleep mode. It wakes up in the advertising mode where the Central is connected to read the logs.

Case 1: When I am setting the following conn_params & Peripheral being connected to Central.

#define MIN_CONN_INTERVAL MSEC_TO_UNITS(7.5, UNIT_1_25_MS) /**< Minimum acceptable connection interval (0.5 seconds). */
#define MAX_CONN_INTERVAL MSEC_TO_UNITS(100, UNIT_1_25_MS) /**< Maximum acceptable connection interval (1 second). */

I can see no current peaks amidst the logs also the current consumption is between 2-3uA , as you can see in the pic below 

Case 2: With the following conn_params & the Peripheral is connected to Central.

#define MIN_CONN_INTERVAL MSEC_TO_UNITS(1000, UNIT_1_25_MS) /**< Minimum acceptable connection interval (0.5 seconds). */
#define MAX_CONN_INTERVAL MSEC_TO_UNITS(1000, UNIT_1_25_MS) /**< Maximum acceptable connection interval (1 second). */

So, in this case, there are current peaks as you can see in the pic below. Consequently, the current consumption has increased as well around 110uA.

Case 3: With the same conn_params as in Case 2 but here the Peripheral is not connected to the Central.

#define MIN_CONN_INTERVAL MSEC_TO_UNITS(1000, UNIT_1_25_MS) /**< Minimum acceptable connection interval (0.5 seconds). */
#define MAX_CONN_INTERVAL MSEC_TO_UNITS(1000, UNIT_1_25_MS) /**< Maximum acceptable connection interval (1 second). */

In this case there will be no peaks similar to the Case 1, and also the current consumption is similar i.e., around 2-3 uA which can be seen from the figure below


Kindly explain the reason why I am getting those peaks between the logs in Case 2 and why there are no peaks in Case 3.
Can I get similar current readings for Case 2 as was in Case 1? Is it possible? If so, kindly help.

Thanks.

[Simonr]

Hi

Thank you for the traces. It does not seem like this extra current is tied to a changed connection interval, and it seems like the spikes are consistently occurring every ~190ms so the most likely culprit is a timer somewhere that triggers and wakes the chip every 190ms. Can you provide some more details on what your application does exactly? Can you also explain how exactly you measure the current consumption. Do you measure the current on a DK or on a custom board, and do you measure the current of the entire board or just the nRF?

What do you mean by "stops logging after 3 logs" exactly? What is one log in this context, one BLE/connection event, or one set of data in I.E. a UART log? I would imagine it goes to sleep after these three logs, which is why it stops. Please check what other functions use the connection interval defines in their functions. You can also do a diff between to make sure that only the connection interval has been changed in the two applications.

Best regards,

Simon