button.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.                 |
;|                                                                           |
;|                                                                           |
;+---------------------------------------------------------------------------+
; Second test of the Cypress EZ-USB
; Makes a LED connected to PB4 follow the state of a button connected to PB5.
;


;+-------------------------------------+
;| 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 0x0000
ljmp init


.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, #00000000b
	movx @dptr, a
	
	mov dptr, #OEB		; Pin PB4 is an output pin
	mov a, #00010000b
	movx @dptr, a


;+--------------+
;| Main program |
;+--------------+		
begin:		
	mov dptr, #PINSB	; Read PB contents
	movx a, @dptr		; and move into accu
	mov r1, #00100000b	; Define bitmask for a propper bit status extraction
	anl a, r1		; AND accu with bitmask in r1
	rr a			; Shift PB5 result into PB4 position
	mov dptr, #OUTB 	; Write result into PB register for output
	movx @dptr, a

	ljmp begin		; Repeat at infinitum