Block-C has two illuminated buttons and thus, more than two cables are needed for the corresponding connection. Each button has four pins in total. Tow pins are for the button operation, and two pins are for the embedded LED. The button operation is supported through the pull-up internal resistors of the microcontroller that are activated within the code. The button LEDs can be connected directly to 5V (using a resistor of 150Ω) for permanent illumination or in digital pins of Arduino for controlling illumination.