Current Optimisation

RE: Current Optimisation

Olfox — Wed, 11 Nov 2020 08:13:00 GMT

I send you by private message :)

Yes that's tru when i'm advertising, it is because i was waoken up by movement, so code is running.

RE: Current Optimisation

Vidar Berg — Wed, 11 Nov 2020 08:03:13 GMT

Could you please post your current implementation of main()? From your PPK plot it seems like the floor current goes up to about 6-7 mA as soon as you enter the advertising or connected state.

RE: Current Optimisation

Olfox — Tue, 10 Nov 2020 17:09:49 GMT

Here is DCDC enable:

I hacve also connected directly my board on nrf PPK ( not through mux on my production board).

Low power:

Advertising current:

Connected:

Spike on the right are some reading with the phone.

So imagine i need to refresh my characteristic each 100ms. Can I be still connected but with cpu in low power ? I'm not sure how softdevice and radio part are independent.

RE: Current Optimisation

Olfox — Tue, 10 Nov 2020 15:05:51 GMT

[quote userid="4240" url="~/f/nordic-q-a/68078/current-optimisation/279270#279270"]Is the external sensor powered in this measurement?[/quote]

No, it was not mounted on the pcb.

Ok i was confused by this in PS:

• Auto-controlled refresh modes for LDO and DC/DC regulators to maximize efficiency

So it seems my systeme only works with LDO reg1 at the moment, and i need to call

sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE); 

Once ble_stack_init(); has been enable 

I have read on some tickets that DCDC only works with Vdd>2.1V then i have to disable it to 
use LDO till 1.8V to win a bit of life time. A good idea to use Power fail comparator can be a good
tmethod to switch when voltage is lower than 2.1V.

1. can you confirm this 2.1V value and behavior, 
because i didn't find this value that seems to comes from nrf51 product.

[quote userid="4240" url="~/f/nordic-q-a/68078/current-optimisation/279270#279270"]The app should call the idle handle when it's not doing anything else like in the original hrs sample.[/quote]

2. Do you mean that i should call advertising_start(erase_bonds);function, and just after call idle_state_handle(); to avoid having cpu during advertising ?

3. Is timeout or connected event generated then?

4. Also, how do you set the TX power in dbm please? I need to check if i am set to 0dbm or not because this big spikes are really high ! Hopefully, i have a good batterys to be able to supply during this spike but i don't think that's normal behavior.

Thank you

RE: Current Optimisation

Vidar Berg — Tue, 10 Nov 2020 13:38:40 GMT

Hi,

You still have to enable the DCDC when you use normal voltage mode. The internal LDO is used by default.

[quote user="Olfox"]ican't have choice here , moreover, it obliged me to add an externel ldo for one sensor that required a fixed voltage[/quote]

Is the external sensor powered in this measurement?

[quote user="Olfox"]Yes the cpu is on when i advertise because i wake up my system with a movement so cpu is wake up and start to advertise. Is it possible to advertise on movement without wake up the cpu ?[/quote]

The app should call the idle handle when it's not doing anything else like in the original hrs sample.

RE: Current Optimisation

Olfox — Tue, 10 Nov 2020 13:29:16 GMT

Hi Vidar,

As you know i'm starting fgrom HRS example. On the module i'm using , VDD and VDDH has been connected together, ican't have choice here , moreover, it obliged me to add an externel ldo for one sensor that required a fixed voltage ... as gpio have same voltage than vdd because it is forced in normal mode.

When i search into the code, i see no call to sd_power_dcdc_mode_set , So i guess that, as specified in Product Specification, it is automatically managed.

Yes the cpu is on when i advertise because i wake up my system with a movement so cpu is wake up and start to advertise. Is it possible to advertise on movement without wake up the cpu ?

RE: Current Optimisation

Vidar Berg — Tue, 10 Nov 2020 12:27:28 GMT

Hi,

The CPU current is around 7 mA if you don't use the DCDC regulator (enabled with sd_power_dcdc_mode_set()). However, the periodic wake-up should have very little impact on the average current consumption, looks like it must be something else that's increasing the average in your case. Can you zoom in on the floor current between the "wake-up" spikes and see what the floor current is?

[quote user=""]2. During Normal systeme mode, I start by advertising, and i was suprised to see big cunsumption around 18mA in spike ! Is it normal ?[/quote]

Are you sure the CPU is going to sleep here? Looks like it might be RADIO+CPU.