Power consumptio when a button is constant pushed

[Svein]

Dear sir/madam

Background:

We have developed a remote-control system where we use nRF52840 and SDK 17.1.0

VDD is 3,0 V

We also use the library “app_button” where “button_high_accuracy” is disabled.

We have defined 6 buttons and use external pullup of 1 MΩ.

Power measurement is done by using Power Profile Kit 2

When no button is pushed, power consumption is approx. 20 µA

 

Question:

When we push a button and kept it pushed, we get a power consumption of approx. 278 µA.

Our circuit is quite simple: GPIO connected to a button with an external pullup of 1 MΩ. Simple calculation says that the currency drawn on that GPIO should be approx. 3 µA. So to my understanding power consumption with a button pushed should be approx. 23 µA.

So, I suspect there is something in app_button.c that generate the power consumption, but maybe I am wrong.

If someone have a hint of why this high currency consumption, I’ll be very happy. 

Kind regards,

Svein

[Nguyen Hoan Hoang]

It is normal that the power consumption is higher 23uA.  MCU is constantly responding to the button interrupt. Meaning the MCU is not sleeping but running at 100%.

[Svein]

Hi Nguyen, 

Thanks for a quick respons. 

Question:

Is the button_app module designed so that interrupts are generated all the time or does the app_button module perform constant scanning of GPIO pins if a button (GPIO) is constantly active? If so, I assume that the module only sends a call to the application when the button status changes.

Kind regards

Svein

[Nguyen Hoan Hoang]

When the button is pressed, an interrupt is generated and call the handler.  That is where the addition consumptions are from.  The more time the button is pressed, the more power consumption it will be.