BIN Circuit Operation
Active low switch circuits, consisting of normally open push buttons and pull-up resistors, are connected to the control inputs; the resistors ensure that the inputs are high when the buttons
are not pressed. The outputs are connected to LEDs in series with current-limiting resistors. The PIC outputs are capable of supplying enough current (up to 20 mA) to drive LEDs directly, making the circuit relatively simple. The external clock circuit consists of a capacitor (C) and resistor (R) in series; the value of C and R multiplied together will determine the chip clock rate. The resistance in this circuit has been made variable, and the values shown should allow the clock frequency to be adjusted to 100 kHz. The reset input (!MCLR) must be connected to the positive supply (รพ5 V). Other unused pins can be left open circuit, and unused input/output (I/O) pins will default to inputs.