Question

+5V PIC18 MCU 300 Ω each STV1 RD5 RD4 10k Ω RD2 RD1 RDO common cathode

A PIC18F4550 microcontroller interfaced to a common-cathode 7-segment display via a buffer IC 74HC244 in the figure above.

- When switch SW1 is pressed, the value displayed at the 7-segment will increment by one.

- If the value displayed at the 7-segment is ‘9’, when switch SW1 is pressed, the value will roll over and become ‘0’.

- When switch SW1 is released, the value displayed at the 7-segment remains unchanged.

- External interrupt is used for detecting the state at RB0.

(a)       Draw the table displaying the relation between the decimal digit to be displayed, corresponding segment to turn on and the corresponding hexadecimal number output from Port D of the microcontroller.[10 marks]

(b)       Write the program that performs these tasks. [10 Marks]

Answer 1