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]

Okay, so when you set the scan duration to 100 by using the define in sdk_config.h the power consumption looks normal ~6mA. The only difference between the two configs (custom and default) I see now is the NRF_BLE_SCAN_BUFFER size (31 vs. 255) but I don't think that's what is hindering the scanning device from going to sleep between scans... Correct me if I'm wrong.

DEFAULT:

CUSTOM: 

Best regards,

Simon

[Pegaze]

Hi,

I don't have my setup at hand but during my tests, I seem to remember that when I configured .scan_phy = BLE_GAP_PHY_1MBPS and not .scan_phy = (BLE_GAP_PHY_1MBPS | BLE_GAP_PHY_CODED), the consumption profile was correct.

Unfortunately, this configuration change greatly impacts the SoftDevice environment and I cannot, from my point of view, explain this behavior.

Best regards,

[Simonr]

So it's not really related to these scan settings in your sdk_config.h at all? Can you test to see if removing the PHY_CODED scan parameter changes the current consumption?

Best regards,

Simon

[Pegaze]

Hi,

Below are the results,

Best regards,

[Pegaze]

This is done on the uart_c project. Unfortunately, I could not provide the results on my custom project before S30

[Simonr]

This seems like the expected current consumption, so I guess that scanning the on the Coded PHY is what increases the current consumption actually then? Can you confirm that this is the only difference between the high and low current consumption measurements in your case?

Best regards,
Simon