Power Consumption - Scanning and Advertising at same time - S140

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Thu, 18 Aug 2022 07:38:50 GMT

These lost scan windows are expected yes, but you should not have to worry about the scanning stopping entirely, as it will always just reschedule the next scan to a free time slot.

Best regards,

Simon

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Wed, 17 Aug 2022 09:24:31 GMT

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,

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Wed, 17 Aug 2022 09:15:09 GMT

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

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Tue, 16 Aug 2022 13:24:47 GMT

Hi,

What I'm afraid of is that advertising will break the long range scan. If the advertising interval is synchronized with the scan window, the Coded PhY risks being destroyed as shown below :

but at each scan interval

Best regards,

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Tue, 16 Aug 2022 13:04:45 GMT

Well, if the scanning is doing something "important" like connecting the advertising won't be allowed to "break" the scanning if that's what you're worried about. Let me know if I misunderstand and you're worried about something else.

Best regards,

Simon

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Tue, 16 Aug 2022 07:43:57 GMT

Hi,

I understand, but it makes it very dangerous to use Coded PHY when we want to advertise at the same time.

Let me explain:

When the device advertise, it cuts off the current scan. If we therefore increase the frequency of advertising, we risk breaking the pattern of the Coded PHY. No ?

Best regards,

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Mon, 08 Aug 2022 08:39:35 GMT

Okay, then that makes more sense, as the Coded PHY is expected to draw more power than the Uncoded PHYs (1MBPS/2MBPS). This is mostly because the Coded PHY transmits all packages 8 times to ensure the longer range it provides, and so the central will need to scan for more time as well, so I think this is only expected.

Best regards,

Simon

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Mon, 25 Jul 2022 13:50:56 GMT

Hi,

Yes, it is the only difference between the high and low current consumption.

Best regards,

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Mon, 18 Jul 2022 09:01:51 GMT

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

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Fri, 15 Jul 2022 09:04:13 GMT

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

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Fri, 15 Jul 2022 09:01:16 GMT

Hi,

Below are the results,

Best regards,

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Fri, 15 Jul 2022 07:47:49 GMT

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

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Wed, 13 Jul 2022 15:15:49 GMT

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,

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Wed, 13 Jul 2022 14:05:51 GMT

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

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Tue, 12 Jul 2022 08:37:00 GMT

Hi,

No, as you asked :

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Tue, 12 Jul 2022 08:28:26 GMT

Just to make sure, the "default scan configuration in this case is with the scan settings set to:

Best regards,

Simon

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Mon, 11 Jul 2022 08:31:40 GMT

Hi,

Here is the result with the default scan configuration of the project

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Mon, 11 Jul 2022 08:20:45 GMT

Hi,

Looks like the scan tries to stop before and after a scan window but is directly pulled to scan.

Best Regards,

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Fri, 08 Jul 2022 12:51:32 GMT

Okay, thank you for the detailed update. Can you, just to rule that part out, try just setting the NRF_BLE_SCAN_SCAN_DURATION to 100 (1 second) instead of 0 and not use your custom snippet so we can rule that out?

Best regards,

Simon

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Thu, 07 Jul 2022 09:44:05 GMT

Hi,

So I used the example you mention and here are my results:

On my custom board
- default configuration

- custom configuration

PCA10056
- default configuration

- custom configuration

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Wed, 06 Jul 2022 13:21:53 GMT

Okay, it still seems like the scanning in these two plots are scanning with a 100% duty cycle (scanning continuously). Can you try reading out the duty cycle (scan window) value when only scanning, as it doesn't seem to be set to 50ms. It only seems to be the advertisements in the 100ms that actually stops the scanning every 100ms, so something seems to be wrong with the duty cycle when the advertiser doesn't run. Do you see the same if you modify a pure central application as well (for example the Nordic UART service Client)?

Best regards,

Simon

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Tue, 05 Jul 2022 08:12:44 GMT

Hi,

Indeed, the default scan configuration is 0 (looping forever) but as you noted, I use the ble_cus_scanconfig_update() function to change it to 1s. To avoid any problem related to my application code, I therefore used the following configuration during my tests:

Yes, I correctly removed all traces of advertising during my "OnlyScan" test, I even checked on the nRF Connect app that my device was no longer visible.

Knowing that scan lasts 1s and that advertising is configured at 3s interval. I just think that on the "Scan + Adv 3s Interval" scheme, we fall between two advertisements, which explains the similarities with the "OnlyScan" scheme.

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Tue, 05 Jul 2022 07:51:09 GMT

Hi again

You say that your scan duration is set to 1 second, but the NRF_BLE_SCAN_SCAN_DURATION seems to be set to 0 (looping forever) in your sdk_config.h file (that shouldn't be the issue though, but more for your information). I think it would be better to change this define to 1 second instead of using the ble_cus_scanconfig_update() function you made yourself. Did you disable advertising altogether for your "Only Scan" power profiler trace, because it seems almost identical to the 3s adv interval trace? Please make sure you disable/remove all mentions of advertising (both init, start, uninit, and so on).

Best regards,

Simon

RE: Power Consumption - Scanning and Advertising at same time - S140

Pegaze — Mon, 04 Jul 2022 13:52:47 GMT

Hi Simonr,

Thanks you for your answer!

I have carried out some tests since our last exchanges and here are my conclusions:

In order to use a sensor on our custom board, I had to implement its driver. Unfortunately too large, it was necessary to use optimization for memory (-02 for size). This caused, for some unknown reason, bluetooth packet transmission issues (seen last week). We decided to remove the use of the sensor temporarily in order to remove the optimization. As a result, the offsets you pointed to are no longer present.

Only Scan:

Scan + Adv 3s interval:

Scan + Adv 100ms interval:

We can discuss the optimization problem but let's focus on the consumption problem.

I wanted a point of comparison. so I used the example code 
ble_app_blinky_c_pca10056_s140.hex

We can observe a difference with my graphs which, after some research, turns out 
to come from the configuration of the scan and more precisely from 
ble_gap_scan_params_t.scan_phys





The only place the scan configuration is changed is here to change the scan duration:



I therefore remain in the misunderstanding of the consumption levels between 
the configurations.

I also carried out tests by deleting the application code but 
I obtain the same consumption results.




Waiting for your feedback, I will adapt my code in order to test it 
on the PCA10056 evaluation board in order to have a common reference.

Best Regards,

Pegaze

RE: Power Consumption - Scanning and Advertising at same time - S140

Simonr — Mon, 27 Jun 2022 10:59:49 GMT

Sorry about the late reply, I was out of office for the Embedded World trade show last week, so I didn't have time to get back to you unfortunately.

But, after looking closer at the Power profiler plots, it seems like the scan window might be causing trouble for you. The scanning process in the two scenarios draw ~2.5mA and ~5.5mA which is huge.

If you compare the scanning plots you see that it scans with ~100 duty cycle on the last plot, vs. ~50% on the first one, see picture above. The red lines mark 100ms intervals. You say that the duty cycle of scanning is at 50% with Scan_Interval = 100ms and Scan_window = 50ms, which means that the top one is what we would expect, but it does seem like it still skips some scanning cycles and are sometimes "stuck" for 100ms.

So it seems like the scanning might not work as intended, either due to the advertising aborting scanning, or by itself. Can you double check that the scan_window is indeed set to 50ms for both scenarios, and try turning off advertising entirely, and see if the scan windows for different intervals seem more correct then?

Best regards,

Simon