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Matrix I/O
The objectives is to use row and column I/O's to expand the number of I/O lines available with the HC11 microcontroller. We were supposed to arrange external elements in a matrix. Therefore we could increase the number of I/O without using time-division multiplexing.
The program requires the use of polling a hexadecimal keypad to see if an ASCII value has been entered into it. The ASCII code would be saved in 2 bytes and then we would combine these 2 bytes to get one byte data for each shape. If the value is within the range of $30 to $5A, then the program will use row/column addressing to look up in a table stored in EEPROM. Then it would display the corresponding character on the 64-segment LED display. If the ASCII code is out of the specified range, then the display should be blank. This program is an infinite loop that stops only the user hit the reset button.