This design implements a 4-bit counter driven by a clock input exposed at the FBIO_0 pad. You need to connect a button to this pin or provide a clock signal from an external clock source. Couter value is exposed to FBIO_21, FBIO_22, FBIO_26 and FBIO_18 which correspond to LEDs 2, 4, 5 and 6 on the Chandalar board (for the “btn_counter-ql-chandalar” target).