High Current Consumption with nRF52840 DK

[jloliveira]

Dear Madam/Sir,

I'm measuring the nRF52840 DK current consumption with my custom ble_peripheral app and other example ble_peripheral apps, namely ble_app_proximity, ble_app_pwr_profiling, and I'm registering in my ampere meter some continuous 0.800mA while advertising/in connection in both example apps (with the default parameters) and 0.200mA in my app. I'm powering the DK with a power supply set at 3.0V. My app is running in DC/DC with the advertise interval set to 2.25s and the connection interval set to 1s, and TX Power set to +9dBm. I also checked my app running on a oscilloscope and the connection/advertise TX peaks measure 14-15mA instead of the supposed 13.6mA.

The nRF Power Source switch is set to VDD, and I attempted both options on the nRF Only / Default switch. When setting the VEXT->nRF ON the consumption even increases.

In all three apps I commented all LOGGING related calls and all LEDs are turned off. I also tried running the DK on all three apps with the CR2032 battery but the current consumption is kept nearly the same. Do I need to also disable the NRF_LOG_ENABLED define in sdk_config.h to make sure it is turned off?

Is there a way to guarantee, through Firmware and/or Hardware, that no pinouts are enabled and causing the high consumption? Is there anything else that may justify such high consumption and that I should take special attention?

Thank you for your help,

João

[jloliveira]

Dear Stian,

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

Thank you,

João

[Stian Røed Hafskjold]

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.

[jloliveira]

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

[Stian Røed Hafskjold]

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

[jloliveira]

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

joliveira-app_tx4dbm_pca10056_s140.hex