Power Profiling Variance on BLE Transmission using PPK2

RE: Power Profiling Variance on BLE Transmission using PPK2

Vidar Berg — Wed, 16 Nov 2022 07:54:52 GMT

Yes, in ampere mode you can connect the PPK2 in series with the battery.

RE: Power Profiling Variance on BLE Transmission using PPK2

jake11212 — Tue, 15 Nov 2022 23:36:15 GMT

[quote userid="4240" url="~/f/nordic-q-a/93560/power-profiling-variance-on-ble-transmission-using-ppk2/395474"]No, in source mode you would have to disconnect the battery and supply the DUT from the PPK.[/quote]

In ampere mode would I be able to put the ppk2 in series with the battery? Sorry I meant to ask about ampere mode in the last question not source mode.

RE: Power Profiling Variance on BLE Transmission using PPK2

Vidar Berg — Mon, 14 Nov 2022 08:14:19 GMT

[quote user="jake11212"]So putting it in source mode with the battery would just be placing the Vin on the positive lead of the battery and vout on the negative lead? [/quote]

No, in source mode you would have to disconnect the battery and supply the DUT from the PPK.

[quote user="jake11212"]I was confused because in the documentation about Ampere meter mode it has both the Vin/Vout on the same pin, so to try and match that originally I put them both on the same Vdd pin on my DUT.[/quote]

They are connected to the same pin header, but not the same pin.

RE: Power Profiling Variance on BLE Transmission using PPK2

jake11212 — Sun, 13 Nov 2022 22:57:39 GMT

So putting it in source mode with the battery would just be placing the Vin on the positive lead of the battery and vout on the negative lead?

I was confused because in the documentation about Ampere meter mode it has both the Vin/Vout on the same pin, so to try and match that originally I put them both on the same Vdd pin on my DUT.

RE: Power Profiling Variance on BLE Transmission using PPK2

Vidar Berg — Wed, 09 Nov 2022 07:41:13 GMT

It does not make sense to have multiple power sources when measuring, so you either have to use an external power source (you can use the PPK2 in source mode for that), or connect the PPK2 in series with the battery.

You also need make the ground connection as shown here: Measuring current in Ampere Meter mode to get common ground between the ppk2 and DUT. I did not include this connection in my sketch.

RE: Power Profiling Variance on BLE Transmission using PPK2

jake11212 — Tue, 08 Nov 2022 19:52:39 GMT

The DUT is currently being powered by a battery. So do I need an external voltage source to run through the PPK2 before reaching the DUT in series? Also in the picture you provided does the circuit complete to gnd of the PPK2?

RE: Power Profiling Variance on BLE Transmission using PPK2

Vidar Berg — Tue, 08 Nov 2022 10:46:59 GMT

[quote user="jake11212"]I changed to source mode and this was the behavior which is more in line with what you saw. How did you change to the line graph? [/quote]

You should see the same if you zoom more in on the waveform. The length of an Advertising event is about 5 ms.

[quote user="jake11212"]Also in my setup I have the same point of Vdd connected to both vin and vout on the ppk2. Do I need two separate points of Vdd for Vin and Vout? I didn't think it would make a difference but I wasn't sure.[/quote]

OK, this explains the strange measurements. The ammeter must be connected in series with the PPK. Otherwise, the current will just flow past the ammeter inside the PPK2.

How to connect VDD in series with the PPK ammeter:

[quote user="jake11212"]A last question I have is about the enable power output toggle. What does it do when the device is in ampere meter mode? And if it is toggled off during source mode does that cause source mode to act as ampere meter mode?[/quote]

As illustrated by the silkscreen on the backside of the PPK2, the power source is not connected in ampere mode. In other words, toggling the power button will have not have any effect in this mode.

RE: Power Profiling Variance on BLE Transmission using PPK2

jake11212 — Mon, 07 Nov 2022 16:29:29 GMT

I changed to source mode and this was the behavior which is more in line with what you saw. How did you change to the line graph?

Also in my setup I have the same point of Vdd connected to both vin and vout on the ppk2. Do I need two separate points of Vdd for Vin and Vout? I didn't think it would make a difference but I wasn't sure.

Is there a reason why source mode would cause the results to change so much? The peaks that I obtained earlier did line up with when the device began advertising confirmed on the nRF toolbox app, so it is definitely reading values from the DUT.

A last question I have is about the enable power output toggle. What does it do when the device is in ampere meter mode? And if it is toggled off during source mode does that cause source mode to act as ampere meter mode?

RE: Power Profiling Variance on BLE Transmission using PPK2

Vidar Berg — Mon, 07 Nov 2022 13:55:59 GMT

OK, thanks for confirming. It sounds like you have set up everything correctly, but the measurements results are wrong for some reason.

Could you please try to use it in source mode instead to see if you can get some more meaningful results?

RE: Power Profiling Variance on BLE Transmission using PPK2

jake11212 — Fri, 04 Nov 2022 14:09:53 GMT

I'm using the PPK2 in Ampere mode. The DUT is a custom board. I connected the Vdd of the custom board to the Vin/Vout circuit of the PPK2 and gnd on the custom board to ground of the PPK2.

RE: Power Profiling Variance on BLE Transmission using PPK2

Vidar Berg — Fri, 04 Nov 2022 12:05:51 GMT

Hello,

There is something wrong with the measurements. The peak currents should have been well above 5 mA for if you were measuring a BLE advertisement event. For comparison, the screenshot below is of an adv. event I measured here on my desk with a nRF52840DK +PPK2 in Source Meter mode.

This also matches the profile shown in the Online Power Profiler for Bluetooth LE if I input the same parameters.

Could you maybe describe your measurement setup in a bit more detail? For instance, if you are using the PPK in Source Meter mode or Ampere mode, and if your DUT is a DK or custom board, etc.

Best regards,

Vidar