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;******************************************************************************
;Software License Agreement                                         
;                                                                    
;The software supplied herewith by Microchip Technology             
;Incorporated (the "Company") is intended and supplied to you, the  
;Company’s customer, for use solely and exclusively on Microchip    
;products. The software is owned by the Company and/or its supplier,
;and is protected under applicable copyright laws. All rights are   
;reserved. Any use in violation of the foregoing restrictions may   
;subject the user to criminal sanctions under applicable laws, as   
;well as to civil liability for the breach of the terms and         
;conditions of this license.                                        
;                                                                    
;THIS SOFTWARE IS PROVIDED IN AN "AS IS" CONDITION. NO WARRANTIES,  
;WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED  
;TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A       
;PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. THE COMPANY SHALL NOT,  
;IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL OR         
;CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.       
; *******************************************************************
; PICkit 2 Lesson 7 - Reversible LEDs
;
; This shows how to read the A2D converter and display the
; High order parts on the 4 bit LED display.
; The pot on the Low Pin Count Demo board varies the voltage 
; coming in on in A0.
;
; Also the switch is used to reverse the direction of rotation
;
; The A2D is referenced to the same Vdd as the device, which 
; is provided by the USB cable and nominally is 5V.  The A2D
; returns the ratio of the voltage on Pin RA0 to 5V.  The A2D
; has a resolution of 10 bits, with 1023 representing 5V and
; 0 representing 0V.
;
;	RA0 - Analog
;	RA1 - Direction
;	RA2 - Step
;	RA3 -
; 	RA4 - Microstep
; *******************************************************************
; * See Low Pin Count Demo Board User's Guide for Lesson Information*
; *******************************************************************
; * NOTE: The PIC16F690 requires the AC162061 header for debugging  *
; *******************************************************************

#define		STEPPIN		porta,2
#define		DIRPIN		porta,1
#define		HALFPIN		porta,4
;
; Decrement 16 bit value, sets Z on exit
;        
; Operation: DST--
;
DEC16   MACRO   DST
        DECF    (DST),F         ; Decrement low byte
        INCFSZ  (DST),W         ; Check for underflow
        INCF    (DST)+1,F       ; Update
        DECF    (DST)+1,F       ; Fixup
        MOVF    (DST),W
        IORWF   (DST)+1,W       ; Set Z bit
        ENDM

#include <p16F690.inc>
     __config (_INTRC_OSC_NOCLKOUT & _WDT_OFF & _PWRTE_OFF & _MCLRE_OFF & _CP_OFF & _BOR_OFF & _IESO_OFF & _FCMEN_OFF)

INT_VAR     UDATA_SHR    
w_temp      RES     1       ; variable used for context saving 
status_temp RES     1       ; variable used for context saving
pclath_temp RES     1       ; variable used for context saving
fsr_temp	res		1
Display  	res		1           ; define a variable to hold the diplay
Direction	res		1
LookingFor	res		1
Step		res		1
Steptime	res		1
d1			res		1
d2			res		1
temp		res		1
halfstep	res		1


     
;**********************************************************************************************************
RESET_VECTOR    CODE    0x0000       ; processor reset vector
        goto    start                ; go to beginning of program

INT_VECTOR      CODE    0x0004       ; interrupt vector location
;**********************************************************************************************************
; ISR
;**********************************************************************************************************
INTERRUPT
; Keep the actual ISR as short as possible. Current code can count pulses up to approx 15kHz
;
; Arrive here on any interrupt - first save the world...
; 
	movwf   w_temp 			; save off current W register contents
	swapf	STATUS,w		; move status register into W register
	movwf   status_temp		; save off contents of STATUS register
	movf    PCLATH,w		; move pclath register into W register
	movwf   pclath_temp		; save off contents of PCLATH register
	movf    FSR,w          	; move fsr register into W register
	movwf   fsr_temp       	; save off contents of PCLATH register

; Actual isr code, determine cause of interrupt. Most likely first

	btfss	intcon, intf	; Was the cause an external interrupt? (RA2)
	goto	exit_interrupt	; no
							; Yes, pulse arrived on RA2
	banksel	Step
	bsf		Step,1			; Set flag to step
	movlw	0x01
	movwf	Steptime		; Stop the currently running step (if any)

	bcf		intcon,intf		; Clear external interrupt flag

;
; Catch-all for interrupt exit. Restore the world as we know it.
;
exit_interrupt
	movf    fsr_temp,w		; retrieve copy of FSR register
	movwf   fsr				; restore pre-isr FSR register contents
	movf    pclath_temp,w	; retrieve copy of PCLATH register
	movwf   PCLATH			; restore pre-isr PCLATH register contents
	swapf   status_temp,w	; retrieve copy of STATUS register
	movwf   STATUS			; restore pre-isr STATUS register contents
	swapf   w_temp,f
	swapf   w_temp,w 		; restore pre-isr W register contents
	retfie 					; return from interrupt
;**********************************************************************************************************
; END ISR
;**********************************************************************************************************
MAIN_PROG       CODE
Start:
	banksel	TRISA
     ;bsf       STATUS,RP0          ; select Register Page 1
     movlw     0xFF
     movwf     TRISA               ; Make PortA all input
     clrf      TRISC               ; Make PortC all output
     movlw     0x10                ; A2D Clock Fosc/8
     movwf     ADCON1
;     bcf       STATUS,RP0          ; back to Register Page 0

     ;bcf       STATUS,RP0          ; address Register Page 2
     ;bsf       STATUS,RP1     
	banksel	ANSEL
     movlw     b'11110001'               ; we want all Port A pins Analog, except RA3.. ra1
     movwf     ANSEL
     ;bcf       STATUS,RP0          ; address Register Page 0
     ;bcf       STATUS,RP1
	banksel	0
     
     movlw     b'00000001'
     movwf     ADCON0              ; configure A2D for Channel 0 (RA0), Right justified, and turn on the A2D module
     movlw     0x08
     movwf     Display
     clrf      Direction
     clrf      LookingFor          ; Looking for a 0 on the button
	clrf		Step
	clrf		Halfstep
	movlw	0
    movwf     PORTC

    banksel   INTCON
    bcf       INTCON, INTF         ; clear interrupt flag
    bsf       INTCON, INTE         ; mask for external interrupts, external interrupt (RA2) is on
    bsf       INTCON, GIE          ; enable interrupts

MainLoop:
	banksel	PORTA
	btfss	DIRPIN					; Direction up?
	goto	GoingUp
	bsf     Direction,0
	goto	MainLoop1
GoingUp
	bcf     Direction,0	

MainLoop1
	btfss	Step,1					; Shall we step?
	goto	MainLoop
	call	Rotate
	goto	MainLoop

;     movf      Display,w           ; Copy the display to the LEDs
;     movwf     PORTC
;     nop                           ; wait 5uS for A2D amp to settle and capacitor to charge.
;     nop                           ; wait 1uS
;     nop                           ; wait 1uS
;     nop                           ; wait 1uS
;     nop                           ; wait 1uS
;     bsf       ADCON0,GO           ; start conversion
;     btfss     ADCON0,GO           ; this bit will change to zero when the conversion is complete
;;     goto      $-1
;	banksel		adresh
;     movf      ADRESH,w
;     movwf     Delay2
;	;clrf	Delay2
;	banksel		adresl
;     movf      ADRESL,w
;     movwf     Delay1
;	clrf		Delay1
;     ;movlw     0xfe                 ; Delay another 10mS plus whatever was above
;	 ;movlw	.50
;     ;movwf     Delay1
;	banksel delay1
;A2DDelayLoop:
;	dec16	delay1
;	btfss	STATUS,Z
;	goto      A2DDelayLoop 
;
     
Rotate:

	banksel	PORTA
	btfss	HALFPIN					; Doing halfsteps?
	goto	DoHalfStep

	bcf		Step,1			; Clear flag to show we stepped
     bcf       STATUS,C            ; ensure the carry bit is clear
     btfss     Direction,0
     goto      RotateLeft
RotateRight:
     rrf       Display,f
     btfsc     STATUS,C            ; Did the bit rotate into the carry?
     bsf       Display,3           ; yes, put it into bit 3.

     goto      RotateWait
RotateLeft:
     rlf       Display,f
     btfsc     Display,4           ; did it rotate out of the display
     bsf       Display,0           ; yes, put it into bit 0

RotateWait
     movf      Display,w           ; Copy the display to the LEDs
     movwf     PORTC

	movlw		.100
	movwf		Steptime

RotateWait1
	call	delay_500us
	 decfsz Steptime, f
	goto	RotateWait1
	movlw	0
    movwf     PORTC

	return

DoHalfStep
								; Page-safe jumptable from AN556. Checks for carry when adding offset and
								; adjusts PCLATH accordingly
	banksel	halfstep
	movf	halfstep,w			; Get display mode in W
	andlw	.7					; Make sure it is within bounds (0..7)
	movwf	temp				; save in temp register
	movwf	halfstep

	movlw	LOW steptable		; Get low address of table
	addwf	temp,F				; add offset
	movlw	HIGH steptable		; Get high 5 bits of address
	btfsc	status,c			; Did we cross a page?
	addlw	1					; Yes, increment high address
	movwf	pclath				; Load high address in latch
	movf	temp,w
	
	movwf	pcl					; Load computed offset into program counter
steptable
	goto	step0 		; Jump table to display mode handlers
	goto	step1
	goto	step2
	goto	step3
	goto	step4
	goto	step5
	goto	step6
	goto	step7

step0
	movlw		b'00000001'
	goto	HalfstepWait

step1
	movlw		b'00000011'
	goto	HalfstepWait

step2
	movlw		b'00000010'
	goto	HalfstepWait

step3
	movlw		b'00000110'
	goto	HalfstepWait

step4
	movlw		b'00000100'
	goto	HalfstepWait

step5
	movlw		b'00001100'
	goto	HalfstepWait

step6
	movlw		b'00001000'
	goto	HalfstepWait

step7
	movlw		b'00001001'
	goto	HalfstepWait

HalfstepWait
	bcf		Step,1			; Clear flag to show we stepped

	btfss     Direction,0
	goto      HalfstepLeft
HalfstepRight:
	incf	halfstep
	goto	Halfstep2
HalfstepLeft:
	decf	halfstep

Halfstep2
	movwf     PORTC

	movlw		.100
	movwf		Steptime

HalfstepWait1
	call	delay_500us
	 decfsz Steptime, f
	goto	HalfstepWait1
	movlw	0
    movwf     PORTC

	return


; http://www.piclist.com/techref/piclist/codegen/delay.htm
delay_5ms
        movlw 0xE7
     movwf d1
     movlw 0x04
     movwf d2
Delay_5ms_0
     decfsz d1, f
     goto $+2
     decfsz d2, f
     goto Delay_5ms_0
     goto $+1
        return


; Delay = 0.0005 seconds
; Clock frequency = 4 MHz

; Actual delay = 0.0005 seconds = 500 cycles
; Error = 0 %


delay_500us
			;499 cycles
	movlw	0xA6
	movwf	d1
delay_500us_0
	decfsz	d1, f
	goto	delay_500us_0

			;1 cycle
	nop
	return
     end
     

Kod: Markera allt

WRITE Address,Value

Write Value to the on-chip EEPROM at the specified Address. This instruction may only be used with a PICmicro that has an on-chip EEPROM data area such as the PIC16F84, PIC16C84 and the PIC16F87x series. WRITE is used to set the values of the on-chip EEPROM at runtime. To set the values of the on-chip EEPROM at programming-time, use the DATA or EEPROM statement. Each WRITE is self-timed and takes about 10 milliseconds to execute on a PICmicro.

If interrupts are used in a program, they must be turned off (masked, not DISABLEd) before executing a WRITE, and turned back on (if desired) after the write instruction is complete. An interrupt occurring during a WRITE may cause it to fail. WRITE will not work on devices with on-chip I2C interfaced serial EEPROM like the 12CE67x and 16CE62x parts. Use the I2CWRITE instruction instead.

Example

WRITE 5,B0 ' Send value in B0 to EEPROM location 5

See Also

READ
I2CREAD
I2CWRITE