BCD to 7-Segment Decoder PAL and Arduino UNO.
To provide external outputs to the board and to create a shield such that we can control it with the microcontroller's output voltage, I have used a transistor shield which also provides isolation between the board's voltage and the microcontroller (Arduino UNO). Also, I have created an Arduino UNO program that makes 4-bit 0 to 15 after certain delay between each number. 4 pins of UNO are connected to the shield and then the shield is connected to the board. Both shield and board have a common ground connection.