Power Consumption - Scanning and Advertising at same time - S140

[Pegaze]

Hi,

I'm working on a project using BLE via s140, everything works fine until I look more seriously at the current draw of the device.

Simply, my project starts a Scan which lasts X milliseconds and which repeats every 20seconds. In parallel, the device advertises at interval Y milliseconds.

I use Power Profiler in order to obtain average consumption values and here are the results for different configurations.

(Note : Scan_Interval = 100ms and Scan_window = 50ms)

Scan duration  = 1s / Adv Interval = 100ms

So we have:

• Average = 273,31uA
• Scan + Adv = 2,44mA
• Adv = 134,93uA

Scan duration  = 1s / Adv Interval = 3s

So we have:

• Average = 293,99uA
• Scan + Adv = 5,74mA
• Adv = 11,78uA

My question is therefore: why when I increase the advertising interval, during Scan + Advertising, I get a significantly higher consumption ?

thanks for your support

[Simonr]

Hi

Okay, thank you for explaining. I understand what you mean, unfortunately this is not something you can control in the app as it is part of the BLE specification and is expected to happen from time to time. Since there is a randomized delay of 0-10ms between advertisements there will always be a chance of this happening when doing both scanning and advertising, and the scanning will then request a new timeslot and do it on the next possible opportunity instead.

Best regards,

Simon

[Pegaze]

Hi,

If I understood your answer correctly, I have no reason to be worried about the loss of one or more scan windows because the softdevice should make up for the losses in the next free time. Isn't it ?

Best regards,