encoder.asm

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY without ev

;+---------------------------------------------------------------------------+
;|                                                                           |
;| Copyright (C) 2002,  Tom De Rybel                                         |
;|                      [e-mail]                                   |
;|                                                                           |
;| This program is free software; you can redistribute it and/or             |
;| modify it under the terms of the GNU General Public License               |
;| as published by the Free Software Foundation; either version 2            |
;| of the License, or any later version.                                     |
;|                                                                           |
;| This program is distributed in the hope that it will be useful,           |
;| but WITHOUT ANY WARRANTY; without even the implied warranty of            |
;| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             |
;| GNU General Public License for more details.                              |
;|                                                                           |
;| You should have received a copy of the GNU General Public License         |
;| along with this program; if not, write to the Free Software               |
;| Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.                 |
;|                                                                           |
;|                                                                           |
;+---------------------------------------------------------------------------+
; Interrupt test of the Cypress EZ-USB
; Makes a LED connected to PB4 blink at a rate controllable by a rotary encoder
; connected to PB6 (A-channel) and PB7 (B-channel)
;


;+-------------------------------------+
;| Declaration of the EZ-USB registers |
;+-------------------------------------+
.equ DPL1,	0x84
.equ DPH1,	0x85
.equ DPS,	0x86
.equ CKCON,	0x8E
.equ SPC_FNC,	0x8F
.equ EXIF,	0x91
.equ MPAGE,	0x92
.equ SCON1,	0xC0
.equ SBUF1,	0xC1
.equ EICON,	0xD8
.equ EIE,	0xE8
.equ EIP,	0xF8
		
.equ CPUCS,     0x7F92	
.equ PORTACFG, 	0x7F93
.equ PORTBCFG, 	0x7F94
.equ PORTCCFG, 	0x7F95
.equ OUTA,     	0x7F96	
.equ OUTB,     	0x7F97
.equ OUTC,     	0x7F98
.equ PINSA,    	0x7F99
.equ PINSB,    	0x7F9A
.equ PINSC,    	0x7F9B
.equ OEA,      	0x7F9C
.equ OEB,      	0x7F9D
.equ OEC,      	0x7F9E

;+-------------------+
;| Interrupt vectors |
;+-------------------+
;
;Reset Vector
.org 0x00
ljmp init
	
;#INT5 Vector
.org 0x5B
;ljmp int5
		
;INT6 Vector
.org 0x63
ljmp int6
		
.org 0x0100
;+-------------------------+
;| Initialisation sequence |
;+-------------------------+
; 
init:
	;;mov	0x92, #0x7F	; tc, allows movx Ri to access ez-usb memory

	mov dptr, #PORTBCFG	; All pins are standard PB pins
	mov a, #01000000b	; Besides PB6 -> INT6
	movx @dptr, a
	
	mov dptr, #OEB		; Pin PB4 is an output pin
	mov a, #00010000b
	movx @dptr, a

	mov IE, #10000000b	; Enable interrupts
	
	mov a, EIE		; Enable INT6 the clean way.
	setb acc.4		; Read, modify and write
	mov EIE, a	

	mov r1,0
		
;+--------------+
;| Main program |
;+--------------+		
;
begin:	
	mov a, r1		; R1 contains the requested delay, as set by
	mov r0, a		; the interrupt routine
	lcall Wait1msec		; The interrupt routine manipulates R0,
				; which is used by the delay loop.
	mov dptr, #OUTB
	mov a, #00000000b
	movx @dptr, a

	mov a, r1
	mov r0, a
	lcall Wait1msec

	mov dptr, #OUTB
	mov a, #00010000b
	movx @dptr, a 
	
	ljmp begin

	
;+-----------------------------+
;| Interrupt 6 service routine |
;+-----------------------------+
;
int6:
	mov dptr, #PINSB	; Read the status on PB
	movx a, @DPTR		
	mov C, acc.7		; Move the PB7 bit into the carry flag

	jc int6_increment	; If carry is 1, add 1 to the counter
	jnc int6_decrement	; If carry is 0, substract 1 form the counter

 int6_increment:		
	mov a, r1		; Move R1 into the accu	
	add a, #0x01		; Add 1 to A
	sjmp int6_end

 int6_decrement:			
	mov a, r1		; Move R1 into the accu
	subb a, #0x01		; Substract 1 from A
	sjmp int6_end

 int6_end:			
	mov r1, a		; Write the result into R1

	mov a, EICON		; Clear the INT6 interrupt flag
	clr acc.3
	mov EICON, a
	
	reti
	

;+----------------------------------------------------------------------+
;| Timing loops taken from the buttons and lights example in USB Design |
;| by Example. These are needed by the LCD routines.                    |
;|                                                                      |
;| A, DPTR and R0 are used and modified.		                |
;+----------------------------------------------------------------------+
;
Wait100msec:
        mov     r0, #100
Wait1msec:                      ; A delay loop
        mov     dptr,#-1200
More:   inc     dptr            ; 3 cycles
        mov     a,dpl           ; + 2
        orl     a,dph           ; + 2
        jnz     More            ; + 3 = 10 cycles x 1200 = 1msec
        djnz    r0, Wait1msec   ; 
        ret