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

Is the connection interval the only thing you change between cases 1 and 2? From the consistent activity I would think this was the nRF reading data from a sensor for example, or using some other peripheral continuously. You're using a PPK2 to do all these measurements, correct? Are the sampling parameters set to the same value in case 1 and 2? I see that they're not in cases 2 and 3 for instance. Can you confirm that the device actually communicates with the central in case 1, doing this data logging at all? Also, what device is this central device?

Best regards,

Simon

[Ankush]

Hi there!
Your quick response is appreciated,

Simonr said:

Is the connection interval the only thing you change between cases 1 and 2?

Yes!

I am using STTS751 Temperature Sensor and W25Q16 Flash Memory.

Simonr said:

You're using a PPK2 to do all these measurements, correct?

Yes!

Simonr said:

Are the sampling parameters set to the same value in case 1 and 2?

Yes! they're the same for cases 1 and 2.
For the 3rd instance, I am attaching an image below with similar sampling parameters

Simonr said:

Also, what device is this central device?

I am using nRF Connect Android app on my smartphone.

Simonr said:

Can you confirm that the device actually communicates with the central in case 1, doing this data logging at all?

Like I said:
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.
So, in cases 1 and 2, I am connecting the Logger in the Advertising mode, but in case 3, I am putting the Logger directly into the data-logging mode without firstly connecting it in the advertising mode.