;
; this program provides an example of how to configure the I2C Interface
; an internal 24500000hz crystal is used as the system clock source.;
;----------------------------------------------------------------


$include (c8051f310.inc)   ; include register definition file.

;----------------------------------------------------------------; EQUATES
;----------------------------------------------------------------

GREEN_LED   equ   P3.3   ; Green LED: '1' is ON	

SMB_MTSTA   equ   0xE0	;(MT) start transmitted
SMB_MTDB    equ   0xC0	;(MT) data byte transmitted	
SMB_MRDB    equ   0x80	;(MR) data byte received

; stack

stack       segment idata        ; declare stack segment
            rseg  stack
            ds    80h            ; reserve 128 bytes for stack

;-----------------------------------------------------------------------------
; bit definitions
;-----------------------------------------------------------------------------
RW 		equ 01 ; R/W command bit. 1=READ, 0=WRITE
SMB_BUSY	equ 02 ; SMBus Busy flag (kept in software)
addr_send	equ 03 ; if set address sent is acknowledged
 

;----------------------------------------------------------------
; byte definitions
;----------------------------------------------------------------

;----------------------------------------------------------------
; reset and interrupt vector table
;----------------------------------------------------------------

cseg at 0           
	    ljmp  main

            org   0bh
            ljmp  timer0_isr  ; timer0 overflow interrupt	
						                  
            org 03Bh
            ljmp SMBus_ISR    ; SMBus Interrupt Vector
;-----------------------------------------------------------------------------
; main program code
;-----------------------------------------------------------------------------

pm33      segment  code                 ; declare code segment
            rseg  pm33                  ; select code segment
            using 0                     ; using register bank 0
;-----------------------------------------------------------------------------
; main subroutines
;-----------------------------------------------------------------------------
main:
            anl   pca0md, #not(040h)      ; clear watchdog enable bit
            mov   sp, #stack-1    ; init stack pointer
	    clr   a                       ; wait at least 1ms
            djnz  acc, $                  ;  wait 512us
            djnz  acc, $                  ;  wait 512us
	    mov   r0,#07fh
clear_RAM:  djnz r0,clear_RAM; to clear the RAM bytes 00 to 7Fh								
            call port_io_init; Initialize ports for SCL,SDA and P3.3 (LED)
	   mov  OSCICN,#083h ; internal oscillator
          lcall timer_init   ; timer initialisation
    	  lcall timer0_init  ; timer 0 initialisation		
    	  acall SMBus_Init   ; Initialize SMBus
	  lcall interrupts_init  ; interrupts enable             
          clr   GREEN_LED        ; Initialize LED to OFF
        
					         
Loop2:      mov   R7, #03h; Code to Blink LED  		
Loop1:      mov   R6, #00h
Loop0:      mov   R5, #00h
            djnz  R5, $
            djnz  R6, Loop0
            djnz  R7, Loop1
            cpl   GREEN_LED; Toggle LED.
	    jmp   Loop2


;-----------------------------------------------------------------------------
; subroutines
;-----------------------------------------------------------------------------
port_io_init:
    ; P0.0  -  SDA (SMBus), Open-Drain, Digital
    ; P0.1  -  SCL (SMBus), Open-Drain, Digital
    ; P0.2  -  Unassigned,  Open-Drain, Digital
    ; P0.3  -  Unassigned,  Open-Drain, Digital
    ; P0.4  -  Unassigned,  Open-Drain, Digital
    ; P0.5  -  Unassigned,  Open-Drain, Digital
    ; P0.6  -  Unassigned,  Open-Drain, Digital
    ; P0.7  -  Unassigned,  Open-Drain, Digital

    ; P1.0  -  Unassigned,  Open-Drain, Digital
    ; P1.1  -  Unassigned,  Open-Drain, Digital
    ; P1.2  -  Unassigned,  Open-Drain, Digital
    ; P1.3  -  Unassigned,  Open-Drain, Digital
    ; P1.4  -  Unassigned,  Open-Drain, Digital
    ; P1.5  -  Unassigned,  Open-Drain, Digital
    ; P1.6  -  Unassigned,  Open-Drain, Digital
    ; P1.7  -  Unassigned,  Open-Drain, Digital
    ; P2.0  -  Unassigned,  Open-Drain, Digital
    ; P2.1  -  Unassigned,  Open-Drain, Digital
    ; P2.2  -  Unassigned,  Open-Drain, Digital
    ; P2.3  -  Unassigned,  Open-Drain, Digital
    ; P3.3  -  Unassigned,  Push-pull, Digital  
		                                 
    orl   P0SKIP, #04h          ; skip LED pin in crossbar
    mov   XBR0,   #004h
    mov   XBR1,   #040h         ; Enable the Port I/O Crossbar
    orl   P3MDOUT,#08h          ; make LED pin output push-pull
    orl   P3MDIN, #08h          ; make LED pin input mode digital
    ret


 
;TIMER INITIALIZATON

timer_init:

    mov  TMOD,#002h  ;Mode 2: 8-bit counter/timer with auto-reload
    mov  CKCON,#004h ;1:Counter/Timer 0 uses the system clock.   
    ret

;INTERRUPT INITIALIZATON

interrupts_init: 
   
setb et0     ; enable timer0	
orl eip1,#01 ;SMB0 interrupt set to high priority level.
setb ea      ; Enable global interrupts
ret          ;TIMER0 INITIALIZATON for SMBus clock source of 100 kHz

timer0_init: mov  TH0,#0AFh
 ;100khz is bit rate from clock source
            ret


;SMBUS INITIALIZATON

SMBus_Init:  mov  SMB0CF,#080h ;SMBUS interface enabled
             setb tr0        ; Timer0 enabled
	     orl eie1,#01h   ; Enable SMBus (SMB0) Interrupt
	     clr SMB_BUSY 	 ; clear the smbus busy flag
    	     ret



SMBus_ISR:    push PSW ;
	      push ACC ;													
SMB_ISR_END:  clr SI; Clear interrupt flag
	      pop ACC
	      pop PSW
	      reti
; end of file.

timer0_isr: reti



end