
Hardware description
Figure 11: Disconnecting the LEDs
The buttons are active low, meaning the input will be connected to ground when the button is activated.
The buttons have no external pull-up resistor, so to use the buttons the P0.13–P0.16 pins must be
configured as an input with an internal pull-up resistor.
The LEDs are active low, meaning that writing a logical zero ('0') to the output pin will illuminate the LED.
Figure 12: Button and LED configuration
6.5.1 I/O expander for buttons and LEDs
The nRF52 Preview Development Kit board has an I/O expander to avoid conflicts with boards that follow
the Arduino standard, the on-board GPIOs for the buttons and LEDs would otherwise possibly conflict with
such boards.
4397_497 v1.2
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