The on-board BLE antenna can be switched on or off using the the SW3 “RF” slide switch on the bottom-right side of the board.
D4…D7: 4x APA102C addressable RGB LEDs.
These RGB LEDs are connected to the nRF52832 over SPI.
Power supply to these RGB LEDs is controlled
PWR_EN signal, connected to a GPIO
of the nRF52832.
Sensirion SHT30-DIS Temperature and humidity sensor
Bosch BMI270 Accelerometer
These sensors are connected to the nRF52832 over I2C, with interrupt lines connected to GPIOs.