R32V2020 PS/2 Keyboard

PS/2 Keyboard

Two interfaces

• x0800-x0FFF (2KB) - PS/2 Keyboard Data
• x1000-x17FF (2KB) - PS/2 Keyboard Status

Keyboard Status

• x01 - Keyboard data present
• x00 - Keyboard data not present

Keyboard Data

• d31..d7 = 0
• d6..d0 - Data from keyboard

Sample Code

Wait for a character from the PS/2 keyboard

;
; waitGetPS2Char
; blocking function - wait for character before returning
; returns character received in r8
;

waitGetPS2Char:
	push	r9
	push	PAR
	lix		PAR,0x1000	; PS/2 Status
waitPS2RxStat:
	lpl		r9			; Read Status into r9
	and 	r9,r9,ONE
	bez 	waitPS2RxStat
getCharFromPS2:
	lix 	PAR,0x0800	; PS/2 keyboard data
	lpl		r8
	pull	PAR
	pull	r9
	pull	PC

Get a character from the PS/2 keyboard

;
; getPS2StatusChar - Check the PS/2 receive data ready status bit
; Non-blocking
; return in r8 - MINUS1 means character not present
; Value other than MINUS1 is the character that was received
;

getPS2StatusChar:
	push	r9
	push	PAR
	lix		PAR,0x1000	; PS/2 Status
waitPS2RxStat:
	lpl		r9			; Read Status into r9
	and 	r9,r9,ONE
	bez 	PS2NotReady
getCharFromPS2:			; character is present
	lix 	PAR,0x0800	; PS/2 keyboard data
	lpl		r8
	bra		PS2CharWasPresent	; skip return of MINUS1
PS2NotReady:
	lix		r8,0xffff
PS2CharWasPresent:
	pull	PAR
	pull	r9
	pull	PC