High Current Consumption with nRF52840 DK

RE: High Current Consumption with nRF52840 DK

jloliveira — Tue, 02 Oct 2018 10:56:21 GMT

Hi Stian,

We tried to consider the LP mode saadc and it seems to indeed decrease the power consumption to normal levels.

Yet, we also tried in Normal ADC mode to initialize the adc before requesting a nrf_drv_saadc_sample and unintialized it after the saadc_event_handler is called and the power consumption also stays at normal levels. Both "always-on LP ADC" mode or "turn_on-read-turn_off Normal ADC" mode seem to retrieve the same voltage measurements.

Are both methods OK to use or would one be more precise than the other?

Thank you,

João

RE: High Current Consumption with nRF52840 DK

Stian Røed Hafskjold — Wed, 19 Sep 2018 09:08:22 GMT

Hi, there is a low power mode in the saadc driver. Please check out this: http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.2.0/hardware_driver_saadc.html?cp=4_0_0_2_0_12_1_1#saadc_nonblocking

http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.2.0/group__nrf__drv__saadc__config.html?cp=4_0_0_6_9_0_19_0_0_1#ga7e7da65888f2c0169a53fbf379c1e79c

RE: High Current Consumption with nRF52840 DK

jloliveira — Fri, 14 Sep 2018 11:38:48 GMT

Hi again Stian,

After a lot of debugging I found the culprit was in the adc_configure() function that I copied from the ble_app_proximity example and which is consuming 500uA continuously. The same applies to the saadc example which makes use of the ADC.

Is it a bug or is there a way to turn of the ADC while we are not using it? In our example, we are using the ADC to read the battery level every 8hours.

Looking forward to your reply,

Thank you,

João

RE: High Current Consumption with nRF52840 DK

jloliveira — Mon, 10 Sep 2018 15:58:17 GMT

Hi Stian,

Thank you for your answer.

As pinouts from the board we are only using 1 Button input and 3 LEDs output (in our custom board associated with a driver that drives a piezo buzzer) that are turned off from start and used on request from a mobile app, through a characteristic. Please find the schematics below in attachment.

We are just using PWM also on demand to light up the LEDs - which is uninitialised when starting the peripheral and after lighting up the LEDs - and no other peripherals.

Could you guess what might be causing such 1mA in idle? You previously referred I had a timer being triggered every 1ms but currently there is none.

Thank you again for your help,

João

RE: High Current Consumption with nRF52840 DK

Stian Røed Hafskjold — Mon, 10 Sep 2018 11:05:22 GMT

Hello,

I measured around 1mA in idle. Seems like some pins are floating (drifting current), so I need the pinout info so I can terminate the floating inputs. A schematic or similar would be nice.

What is the expected idle current? Are you running PWM, UART or any other peripherals?

RE: High Current Consumption with nRF52840 DK

jloliveira — Fri, 07 Sep 2018 17:30:34 GMT

Dear Stian,

Did you have the opportunity to check my previous message, and could you please check if the current consumption of the final .hex I sent is now at normal levels?

Thank you very much,

João

RE: High Current Consumption with nRF52840 DK

jloliveira — Tue, 04 Sep 2018 18:43:53 GMT

Dear Stian,

Hope this message finds you well after so long.

The development of our peripheral app is finally finished (with the nrf_drv_pwm_uninit() taken into account) and successfully migrated to SDK15 and SoftDevice6.0.0, while also making use of NFC T4T with read/write capabilities.

Can you please test the final .hex in attachment and check if the current consumption is now at normal levels for both advertising and connection, considering a Tx Power of +4dBm for both?

Thank you,

João

devzone.nordicsemi.com/.../joliveira_2D00_app_5F00_tx4dbm_5F00_pca10056_5F00_s140.hex

RE: High Current Consumption with nRF52840 DK

Stian Røed Hafskjold — Wed, 18 Apr 2018 12:56:39 GMT

You need to call nrf_drv_pwm_uninit() when you're not using the pwm. Try this and see what happens.

RE: High Current Consumption with nRF52840 DK

jloliveira — Mon, 16 Apr 2018 14:24:55 GMT

Hi Stian,

Thank you for your reply.

I guess the 1ms timer was still there due to a missing #define in the code that activates it in debug mode - I'll send you a corrected .hex as soon as I solve the PWM issue you refer to.

How come the PWM consumes 0.5mA in idle mode? I just use the PWM to ring a buzzer for 10secs when requested by the user via mobile-app. How should I make sure the PWM is only activated and consuming when the user requires to ring the buzzer, and is totally deactivated afterwards?

Thank you,

João

RE: High Current Consumption with nRF52840 DK

Stian Røed Hafskjold — Mon, 16 Apr 2018 13:49:51 GMT

Hi sorry for the late reply. I checked the current consumption and I can see that you have enabled the PWM. Unfortunately the PWM requires the HF clock to be running all the time, which gives about 0.5mA consumption in idle. Also, I still see the 1ms spikes. This adds up to about 750 uA in idle for both of the hex files you sent.

RE: High Current Consumption with nRF52840 DK

jloliveira — Fri, 13 Apr 2018 16:05:26 GMT

Dear Stian,

Any news regarding my previous message and new power consumption tests?

Thank you,

João

RE: High Current Consumption with nRF52840 DK

jloliveira — Mon, 09 Apr 2018 12:02:38 GMT

Dear Stian,

Thank you very much for your clarification and tests.

I found the culprit for the 1ms timer you reported, cleaned the whole code and migrated the app to SDK15 and Softdevice6.0.0, with TX_Power +8dB/+4dBm and NRF_LOG_ENABLE = 0, but now also using the PWM Driver, which is initialised in the beginning but only operated via characteristic commands to control the LEDs.

Can you please retest the .hex file in attachment in advertise and connection modes, with TX_Power +8dBm and TX_Power +4dBm, to check the overall current consumption and if there are still means to decrease it?

Thank you,

João

devzone.nordicsemi.com/.../jloliveira_2D00_app_5F00_tx8dbm_5F00_pca10056_5F00_s140.hex

devzone.nordicsemi.com/.../jloliveira_2D00_app_5F00_tx4dbm_5F00_pca10056_5F00_s140.hex

RE: High Current Consumption with nRF52840 DK

Stian Røed Hafskjold — Thu, 15 Mar 2018 12:09:08 GMT

NRF_LOG_ENABLED = 0 also ensures that the UART peripheral is not turned on, which is the reason for the current consumption. Not the logging data itself. So it might not be enough to only avoid logging calls. But I'm not sure how you did it, so maybe it works. Anyways, in the hex files you sent, logging seems to be properly turned off. So I'm attaching plots from the measurements below

From what I can see you have a timer which wakes up the chip every 1ms. This leads to an additional 140 uA in idle (between BLE events)

During advertising (2.25s interval) average current is 151 uA:

In connection I see that you continue to advertise every 4 seconds, and connection interval is about 1.16 s? Average current is 148 uA:

To compare with the pwr_profiling application you sent. You can see that the idle current is a lot lower:

A good idea would be to increase the timer wakeup interval. You should be able to get the idle current down a lot by increasing the interval.

Last plot is the pwr_profiling hex you sent with log disabled. You can use this as a reference for your measurements. As far as I know all the examples in the SDK has logging enabled by default.

Regarding the radio current in the PS v0.5 pdf, this is an old version of the PS, the newest is now 0.5.1. The numbers are expected to change because this is still an alpha release of the documentation.

HFCLK and DMA are only running when requested by peripherals (unless you manually start the HF crystal). The radio needs HFCLK and DMA, hence they are requested, and can not be turned off during radio activity. After the BLE event they will be turned off and therefore will not have an impact on idle current.

RE: High Current Consumption with nRF52840 DK

jloliveira — Wed, 14 Mar 2018 21:38:15 GMT

Dear Stian,

Any news regarding my previous message and questions?

Thank you,

João

RE: High Current Consumption with nRF52840 DK

jloliveira — Wed, 07 Mar 2018 18:43:24 GMT

Dear Stian,

Thank you for your help.

Regarding the Logging, I didn't know setting NRF_LOG_ENABLED to 0 would be enough to totally disable Logging. Yet, I have a define that unconsiders all Logging calls, thus it shouldn't consume. I don't have access to the measuring instruments right now, so I just set NRF_LOG_ENABLED to 0 and send you the hex file in attachment for your measurements - thank you very much for it. If possible, please provide me the measurements in advertise and connection modes.

But is there any ble_peripheral example that is optimized for low consumption, running DC/DC, and that I should consider for comparison? I also send you in attachment the hex of the original ble_app_pwr_profiling with NRF_LOG_ENABLE set to 0 for your measurements (have to press button1 for it to start).

Regarding the TX peak current, although the infocenter reports 14.1mA at +8dBm, the PS pdf in page 286 states that it consumes 13.6mA at +9dBm, both DC/DC at 3V. Why the difference?

And is HFCLK and DMA 0.8mA current drain supposed to occur persistently during run-time or only during radio events? Is there a way to turn them off?

devzone.nordicsemi.com/.../jloliveira_2D00_app_5F00_pca10056_5F00_s140.hex devzone.nordicsemi.com/.../ble_5F00_app_5F00_pwr_5F00_profiling_5F00_pca10056_5F00_s140.hex

Thank you,

João

RE: High Current Consumption with nRF52840 DK

Stian Røed Hafskjold — Wed, 07 Mar 2018 15:48:32 GMT

Hi, most likely the current you are seeing is because of logging. The best way to disable this is to set NRF_LOG_ENABLED to 0 in sdk_config.h. You should leave all the logging related calls in the code as they are originally, setting NRF_LOG_ENABLED to 0 is sufficient to completely disable logging.

When using the VEXT->nRF switch the current bypasses the debugging chip (and everything else on the DK) and goes directly from P21 (external supply) to nRF. Because of this you need to keep the main USB cable connected in order to power the rest of the components on the chip. Otherwise you get higher current draw.

If you want you can post your hex file here and then I can do measurements for you.

Regarding the radio TX peak current. You mean +8dBm right? From the PS:

I_{TX,PLUS8dBM,DCDC}

TX only run current (DCDC, 3V) P_RF =+8 dBm

14.1

Also, this current is without HFCLK and DMA current. So you should add another 0.8mA to this. The current consumption scenarios chapter in the PS is supposed to cover this, but it does not include +8dBm yet unfortunately. http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52840.ps/pmu.html#unique_1132745023