117 lines
3.8 KiB
NASM
117 lines
3.8 KiB
NASM
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jp main ; Startup vector: DO NOT MOVE! Must be the first instruction
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; Tests TM404A, on ports 2 and 3
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IO_2: EQU 0x40
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IO_3: EQU 0x60
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LCD_TOP_INSTR_REG: EQU IO_2
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LCD_TOP_DATA_REG: EQU IO_2 + 1
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LCD_BOTTOM_INSTR_REG: EQU IO_3
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LCD_BOTTOM_DATA_REG: EQU IO_3 + 1
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; Inits the lcd display
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LCD4004_init:
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; --- Init first controller ---
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; The following are documented as in the datasheet: RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
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; Function set: 0 0 0 0 1 DL N F 0 0 (DL: 8-bit/4-bit, N: number of display lines 2/1, F: Font type 11dots/8dots)
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; 0000111000 (8 bit, 2 lines)
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ld a,0x38
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out (LCD_TOP_INSTR_REG),a
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call LCD4004_wait_busy_clear
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; Display ON/OFF Control: 0 0 0 0 0 0 1 D C B (D: display on/off, C: cursor on/off, B: blinking cursor on/off)
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; 0000001111 (display on, blinking cursor)
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ld a,0x0F
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out (LCD_TOP_INSTR_REG),a
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call LCD4004_wait_busy_clear
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; Clear display
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; 0000000001
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ld a,0x01
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out (LCD_TOP_INSTR_REG),a
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call LCD4004_wait_busy_clear
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; --- Init second controller ---
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; The following are documented as in the datasheet: RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
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; Function set: 0 0 0 0 1 DL N F 0 0 (DL: 8-bit/4-bit, N: number of display lines 2/1, F: Font type 11dots/8dots)
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; 0000111000 (8 bit, 2 lines)
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ld a,0x38
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out (LCD_BOTTOM_INSTR_REG),a
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call LCD4004_wait_busy_clear
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; Display ON/OFF Control: 0 0 0 0 0 0 1 D C B (D: display on/off, C: cursor on/off, B: blinking cursor on/off)
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; 0000001111 (display on, blinking cursor)
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ld a,0x0F
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out (LCD_BOTTOM_INSTR_REG),a
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call LCD4004_wait_busy_clear
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; Clear display
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; 0000000001
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ld a,0x01
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out (LCD_BOTTOM_INSTR_REG),a
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call LCD4004_wait_busy_clear
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ret
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; Prints string
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; @param BC Pointer to a null-terminated string first character
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LCD4004_TOP_print:
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ld a, (bc) ; bc is the pointer to passed string's first char
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cp 0 ; compare A content with 0 (subtract 0 from value and set zero flag Z if result is 0)
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ret z ; if prev compare is true (Z flag set), string is finished, return
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out (LCD_TOP_DATA_REG),a ; output char
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call LCD4004_wait_busy_clear ; wait for the lcd to execute (busy signal check)
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inc bc ; increment bc to move to next char
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jp LCD4004_TOP_print
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; Prints string
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; @param BC Pointer to a null-terminated string first character
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LCD4004_BOTTOM_print:
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ld a, (bc) ; bc is the pointer to passed string's first char
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cp 0 ; compare A content with 0 (subtract 0 from value and set zero flag Z if result is 0)
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ret z ; if prev compare is true (Z flag set), string is finished, return
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out (LCD_BOTTOM_DATA_REG),a ; output char
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call LCD4004_wait_busy_clear ; wait for the lcd to execute (busy signal check)
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inc bc ; increment bc to move to next char
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jp LCD4004_BOTTOM_print
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; Waits for the busy flag to be clear, indicating the LCD controllers to have finished their work
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LCD4004_wait_busy_clear:
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ret
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in a, (LCD_TOP_INSTR_REG) ; reads the status
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rla ; busy flag is DB7, so we shift it into carry to check it
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jp c, LCD4004_wait_busy_clear ; if carry is set, lcd is busy
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in a, (LCD_BOTTOM_INSTR_REG) ; reads the status
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rla ; busy flag is DB7, so we shift it into carry to check it
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jp c, LCD4004_wait_busy_clear ; if carry is set, lcd is busy
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ret
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; --- TEST CODE ---
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main:
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TEST_STR_80: DB "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam augue tortor sed.",0 ; null terminated string
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TEST_STR_85: DB "2Lorem ipsum dolor sit amet, consectetur adipiscing elit praesent pellentesque nisi.",0 ; null terminated string
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; Init display
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call LCD4004_init
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; Write string on first 2 lines
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ld bc, TEST_STR_80
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call LCD4004_TOP_print
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; Write long string on last 2 lines (to see how it wraps)
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ld bc, TEST_STR_85
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call LCD4004_BOTTOM_print
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halt
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