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

Can you export the PPK trace of Case 2 and upload it here on DevZone in a .zip file so we can do a review. Or alternatively zoom in on the events between the data logging events so we can get a better look at them to determine if it's just random noise or BLE events (which it looks like).

My guess is that the slave latency is affected by the connection interval changing, and that this causes more BLE activity than you bargain for. Are any other parameters affected by the changed connection intervals?

Best regards,

Simon

[Ankush]

I have uploaded the trace of cases 1 and 2 separately as well as combinedly
Trace_1_2_1+2.zip

Simonr said:

Are any other parameters affected by the changed connection intervals?

Yea, you'll notice that in case 2 the BLE peripheral automatically stops logging after 3 logs, which is not the case in case 1. Kindly explain the reason behind this as well.