Basic 8051 tutorial 4 2014-04-18

    org    0        ; Reset vector
    sjmp    Start

    org    30H        ; Code starts here
Start:
    acall     LcdInit        ; Initialise screen
While:  
    acall    LcdGotoline1
    mov    DPTR,#mess1    ; Get message 1
    acall    LcdPrint
    acall    LcdGotoline2
    mov    DPTR,#mess2    ; Get message 2
    acall    LcdPrint
    mov    A,#0CDH        ; Line 2 position 13
    acall    LcdCmd
    jb     P0.0, SW2    ; Is switch one pressed
    mov    A,#31H        ; print a '1'
    acall    LcdData
SW2: 
    jb    P0.1,NS        ; Is switch two pressed
    mov    A,#32H        ; print a '2'
    acall    LcdData
NS:  
    sjmp    While        ; Back to loop

; Screen Init..
;---------------
LcdInit:
    clr    P3.6
    clr    P3.7
    acall    Delay15        ; Settle time
    mov    P1,#33H        ; Init 1
    setb    P3.5
    nop
    clr    P3.5        ; Init 2
    acall    Delay5
    setb    P3.5
    nop
    clr    P3.5
    acall    Delay1
    mov    A,#38H        ; Function set 38
    acall    LcdCmd
    mov    A,#0CH        ; Display on
    acall    LcdCmd
    mov    A,#06H        ; cursor off
    acall    LcdCmd
    mov    A,#01H        ; Clear and home..
    acall    LcdCmd
    ret

; Screen goto
;---------------
LcdGotoline1:
    mov    A,#080H        ; Home 0,0
    acall    LcdCmd
    ret

LcdGotoline2:
    mov    A,#0C0H        ; Home 0,1
    acall    LcdCmd
    ret

; Screen Print
;---------------
LcdPrint:
    clr    A
Lp:  
    push    Acc        ; save index
    movc    A,@A+DPTR    ; Get character
    jz    Fin        ; NULL terminator
    acall    LcdData        ; place on screen
    pop    Acc
    inc    A        ; Increase index
    sjmp    Lp        ; Next character
Fin:  
    pop    Acc
    ret            ; Done

; Screen Busy
;---------------
LcdBusy:
    mov    P1,#0FFH    ; Port as input
    clr    P3.7        ; RS = 1
    setb    P3.6        ; RW = 0
    setb    P3.5        ; E on
    nop
    mov    A,P1        ; Busy flag
    clr    P3.5        ; E off
    clr    P3.6        ; RW = off
    ret

; Screen data
;---------------
LcdData:
    push     Acc        ; save data
Dbusy:  
    acall    LcdBusy        ; See if screen is ready
    jb    Acc.7,DBusy    ; Loop until it is
    pop    Acc        ; get data
    setb    P3.7        ; RS = 1
    clr    P3.6        ; RW = 0
    mov    P1,A        ; Data to screen
    setb    P3.5        ; E on
    nop
    clr    P3.5        ; E off
    clr    P3.7        ; RS = off
    ret

; Screen command
;---------------
LcdCmd:
    push     Acc        ; save data
Cbusy: 
    acall    LcdBusy        ; See if screen is ready
    jb    Acc.7,CBusy    ; Loop until it is
    pop    Acc        ; get data
    clr    P3.7        ; RS = 0
    clr    P3.6        ; RW = 0
    mov    P1,A        ; Command to screen
    setb    P3.5        ; E on
    nop
    clr    P3.5        ; E off
    ret

delay15:
    mov    R2,#1BH        ; Aproximately 15mS
    sjmp    delay
Delay5:
    mov    R2,#0AH        ; aproximately 5mS
    sjmp    delay
Delay1:
    mov    R2,#2H        ; Aproximately 1mS
delay: 
    mov    R1,#0        ; 2 clock cycles (loading)    = 2
d1: 
    djnz    R1,d1        ; 2 * 256 clock cycles *180    = 92160
    djnz    R2,d1        ; 2 * 180 clock cycles     = 380
    ret            ; 2 clock cycles (return)    = 2
                ; * 1.0815 (11.0952 osc)    = 100.07ms

Mess1:    db    "  PRESS A KEY   ",0
Mess2:    db    "YOU PRESSED:    ",0 

    END

#include<8051.h>        // definition file

#define LCDPORT P1

__sbit __at (0xB7) RS;    // Register select pin
__sbit __at (0xB6) RW;    // Read write pin
__sbit __at (0xB5) E;    // Enable pin


void delayUs(int x)
    {                // As I don't need uS delays:----
    x/=19;            // Explanation:  This takes 380uS
    while(x--);        // This takes 11uS 1000 / 19 = 52.
    }                // 52 * 11uS + 380uS + 4uS = 963uS
 
void delayMs(int x)
    {
    while(x--)
        delayUs(1000);    // 13uS + 963uS = 976uS (close enough )
    }
 

unsigned char LcdBusy(void)
    {
    char ERR = 0;
    LCDPORT = 0xFF;            // Port as input
    RS = 0;                    // Set for command
    RW = 1;                    // Set to read
    E = 1;                    // Clock on
    ERR = LCDPORT & 0x80;    // Bit 7 is busy flag
    E = 0;                    // Clock off
    RW = 0;                    // Set to write
    if(ERR)return 1;        // Return 1 or 0
    return 0;
    }
 
void LcdCmd( unsigned char C)
    {
    while(LcdBusy());        // Wait until not busy
    RS = 0;                    // Set to command
    RW = 0;                    // Set to write
    LCDPORT = C;            // Write command
    E = 1;                    // Clock
    E = 0;     
    }
 
void LcdData( unsigned char C)
    {
    while(LcdBusy());        // Wait until not busy
    RS = 1;                    // Set to Data
    RW = 0;                    // Set to write
    LCDPORT = C;            // Write Data
    E = 1;                    // Clock
    E = 0;     
    } 
void LcdInit(void)
    {
    delayMs(50);    // Setting time
    RS = 0;            // Command
    RW = 0;            // Write
    LCDPORT = 0x33;    // Init value
    E = 1;            // Clock
    E = 0;
    delayMs(15);    // Twice
    E = 1;            // Clock
    E = 0;
    delayMs(5);        // Ready to start
    LcdCmd(0x38);    // Function set
    LcdCmd(0x0C);    // Display command
    LcdCmd(0x06);    // Cursor conmmand
    LcdCmd(0x01);    // Clear and Home command
    }
 
void LcdClear(void)
    {
    LcdCmd(1);        // Clear and Home
    }
 
void LcdPrintRam(unsigned char* str)
    {
    while(*str != 0)
        LcdData(*str++);    // Print until NULL
    }
 
void LcdPrintConst( const char * str)
    {
    LcdPrintRam((unsigned char *) str);    //Convert to ram and print
    }
 
void LcdGoto(unsigned char x, unsigned char y)
    {
    x += 0x80;                // Line 1
    if(y==1) x+=0x40;        // Line 2
    LcdCmd(x);                // Line Command
    }                        // For 4 line use 0xD4 and 0x94 as well..
 
void main(void)            // Main entry point
    {
    LcdInit();            // Get screen ready
 
    while(1)            // Forever loop
        {
        LcdGoto(0,0);
        LcdPrintConst("   PRESS A KEY   ");
        LcdGoto(0,1);
        LcdPrintConst("YOU PRESSED:     ");
        LcdGoto(13,1);
        if(!P0_0) LcdData(0x31);
        if(!P0_1) LcdData(0x32);     
        } 
    }