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

Seems like the CPU is running idly inbetween advertisements, which is why the current is so high. When the advertising interval is this big, I think it will be better to go to sleep between advertisements so the CPU is turned off/down to reduce current consumption here.

Best regards,

Simon

[Pegaze]

Hi Simonr,

Thank you for your rely !

I understand what you are suggesting and I agree with you. But, I feel like i'm sleeping inbetween advertisements (11uA cf. pic 4 with adv interval = 3s).

What I don't understand is the behavior during the Scan. Why in example 1 the device entres sleep:

While we have an advertising interval of 100ms and when we increase this interval to 3000ms (therefore leaving more time to sleep) we observe an increase in consumption.