New Micros NMIY-0031, Manual

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2 / 2 6 / 2 0 0 2 2 : 0 6 P M 2 / 2 6 / 2 0 0 2 4 0
N M I Y - 0 0 3 1 P R O G R A M S E G M E N T S
O FE FFFC ; Check column 1
D FFFC FE ; Read row
O FD FFFC ; Check column 2
D FFFC FF ; Read row
O FB FFFC ; Check column 3
D FFFC FF ; Read row
O F7 FFFC ; Check column 4
D FFFC FF ; Read row
O EF FFFC ; Check column 5
D FFFC FF ; Read row
Each of the
D FFFC
commands returns a two digit hex value corresponding to the key pressed.
The column value scanned when a non-FF return occurs, indicates the column pressed. Valid
return values are FE, FB, FD, and F7. When a key in row 1 is pressed, then the one bit is
returned as zero, FE. Row 2 returns FB, row 3 returns FD, and row 4 returns F7. The value
returned by any other column will be FF.
E X A M P L E
If the key in row 3, column 2 is pressed, then after entering:
O FD FFFC
D FFFC FB
the value FB is returned, while all other columns will return FF. The FB hex return value
signifies a row 2 key is pressed. Bit 2 of FB has a zero value which identifies the row as 3.
Remember to hold the key-pad key down while entering the “ D “ commands. If row 1 has a
key pressed, the return value will be FE, row 2 would return FD, row 3 FB, and row 4 F7.
Whenever a D command returns a value other than FF, the row pressed is determined by
examining the return value.
The examples that follow assume use of a 4 line by 40 character LCD, and a 4 row by 5 column
keypad. If other device configurations are used, it will be necessary to adjust either some values
or interpretations of results.