;
;****************************************************************************
;
;  Purpose:
;	Provides Connection From LCD Driver Code To Hardware
;
;  Date:
;	07/21/92
;
;  Author:
;	John C. Wren
;
;  Modications:
;	02/04/97 - Added Description Fields For Archive
;
;  Processor:
;	Generic 8031
;
;  Assembler:
;	Avocet AVA51
;
;  Dependencies:
;	None
;
;  Files:
;	None
;
;  Philosophic:
;	This Is An Extract Of The Generic IO.ASM File.  Usually, All I/O
;	Support Is Incorporated Into One File.  A Version Of This Is Made
;	For The Real Hardware, And If There Is A Prototype Board, A Verison
;	Is Created To Support It
;
;****************************************************************************
;
;  Includes
;
;		%include "equates.inc"
		seg	code
;
;****************************************************************************
;
;  Publics
;
		public	IO_INIT
		public	IO_LCDRS_LO
		public	IO_LCDRS_HI
		public	IO_LCDEN_LO
		public	IO_LCDEN_HI
		public	IO_LCDRW_LO
		public	IO_LCDRW_HI
		public	IO_LCD_WR
		public	IO_LCD_RD
;
;*******************************************************************************
;
;  Equates
;
LCDEN		bit	p3.0			; LCD Enable
LCDRW		bit	p3.1			; LCD R/W
LCDRS		bit	p3.2			; LCD Register Select
LCDDATA		equ	p1			; LCD Data Register
;
;****************************************************************************
;
;  Description:
;	Initializes Various I/O To A Known State.  
;
;  Entry Requirements:
;	None
;
;  On Exit:
;	None
;
;  Affected:
;	None
;
;  Stack:
;	0 Bytes, Not Including Called Routines
;
;  Comments:
;	This Should Be Called Before The Global Interrupts Are Enabled (EA)
;
IO_INIT		proc
		clr	LCDEN			; LCD De-Selected
		setb	LCDRW			; LCD To Read Mode
		setb	LCDRS			; LCD Data Register Selected
		ret				; Return To Caller
		endproc
;
;****************************************************************************
;
;  Description:
;	Set The LCD Register Select Line To The Data State
;
;  Entry Requirements:
;	None
;
;  On Exit:
;	None
;
;  Affected:
;	None
;
;  Stack:
;	0 Bytes, Not Including Called Routines
;
;  Comments:
;	None
;
IO_LCDRS_LO	proc
		clr	LCDRS			; Select Command Register
		ret				; Return To Caller
		endproc
;
;****************************************************************************
;
;  Description:
;	Set The LCD Register Select Line To The Command State
;
;  Entry Requirements:
;	None
;
;  On Exit:
;	None
;
;  Affected:
;	None
;
;  Stack:
;	0 Bytes, Not Including Called Routines
;
;  Comments:
;	None
;
IO_LCDRS_HI	proc
		setb	LCDRS			; Select Data Register
		ret				; Return To Caller
		endproc
;
;****************************************************************************
;
;  Description:
;	Set The LCD Enable Line To The Inactive State
;
;  Entry Requirements:
;	None
;
;  On Exit:
;	None
;
;  Affected:
;	None
;
;  Stack:
;	0 Bytes, Not Including Called Routines
;
;  Comments:
;	None
;
IO_LCDEN_LO	proc
		clr	LCDEN			; Enable Low
		ret				; Return To Caller
		endproc
;
;****************************************************************************
;
;  Description:
;	Set The LCD Enable Line To The Active State
;
;  Entry Requirements:
;	None
;
;  On Exit:
;	None
;
;  Affected:
;	None
;
;  Stack:
;	0 Bytes, Not Including Called Routines
;
;  Comments:
;	None
;
IO_LCDEN_HI	proc
		setb	LCDEN			; Enable High
		ret				; Return To Caller
		endproc
;
;****************************************************************************
;
;  Description:
;	Set The LCD Read/Write Line To The Write State
;
;  Entry Requirements:
;	None
;
;  On Exit:
;	None
;
;  Affected:
;	None
;
;  Stack:
;	0 Bytes, Not Including Called Routines
;
;  Comments:
;	None
;
IO_LCDRW_LO	proc
		clr	LCDRW			; Select Write
		ret				; Return To Caller
		endproc
;
;****************************************************************************
;
;  Description:
;	Set The LCD Read/Write Line To The Read State
;
;  Entry Requirements:
;	None
;
;  On Exit:
;	None
;
;  Affected:
;	None
;
;  Stack:
;	0 Bytes, Not Including Called Routines
;
;  Comments:
;	None
;
IO_LCDRW_HI	proc
		setb	LCDRW			; Select Read
		ret				; Return To Caller
		endproc
;
;****************************************************************************
;
;  Description:
;	Write A Byte To The LCD Data Lines
;
;  Entry Requirements:
;	Acc Has Character To Setup To LCD Data Lines
;
;  On Exit:
;	None
;
;  Affected:
;	None
;
;  Stack:
;	0 Bytes, Not Including Called Routines
;
;  Comments:
;	This Could Be Modified To Support An LCD Connected To The External
;	Data Bus, Rather Than Port Pins.
;
IO_LCD_WR	proc
		mov	LCDDATA,a		; Write To Data Bus
		ret				; Return To Caller
		endproc
;
;****************************************************************************
;
;  Description:
;	Read A Byte From The LCD Data Lines
;
;  Entry Requirements:
;	None
;
;  On Exit:
;	Acc Has Character Read From The LCD Data Lines
;
;  Affected:
;	PSW.Z, PSW.P, Acc
;
;  Stack:
;	0 Bytes, Not Including Called Routines
;
;  Comments:
;	This Could Be Modified To Support An LCD Connected To The External
;	Data Bus, Rather Than Port Pins.
;
IO_LCD_RD	proc
		mov	LCDDATA,#0ffh		; Configure As Inputs
		mov	a,LCDDATA		; Write To Data Bus
		ret				; Return To Caller
		endproc
;
;****************************************************************************
;
		end