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Chapter 2: TI-83 Plus Specific Information 79

TI-83 Plus Developer Guide Third Release May 28, 2002

Reading the Display Driver After Setting X or Y Coordinates

A dummy read needs to be done after setting either the x or y coordinate of the driver if

one wants to read from the driver. For example, read nine bytes of data from the display

starting in LCD row 5, column 1, to OP1.

LD A,85h

CALL lcd_busy_2

OUT (lcdinstport),A ; set X to row 5

;

LD A,07h

CALL lcd_busy_2

OUT (lcdinstport),A ; set Y auto increment mode

;

CALL lcd_busy_2

LD A,21h

OUT (lcdinstport),A ; set Y to column 1

;

LD B,9 ; number of bytes to read

LD HL,OP1

CALL lcd_busy_2

IN A,(lcddataport) ; dummy read since we changed

; X, Y position

Loop:

CALL lcd_busy_2

IN A,(lcddataport) ; read byte, auto increment Y

;

LD (HL),A

INC HL

DJNZ Loop

;

LD A,05h

CALL Lcd_busy_2

OUT (lcdinstport),A ; set X auto increment mode

• Writing to the display driver RAM

CALL lcd_busy_2

OUT (lcddataport),A ; write byte to disp

Texas Instruments TI-83-Plus User Manual

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