Table of Contents PS/2 Keyboard Software Interface Address i_RegSel - Register Select = 0 - Status register Address i_RegSel - Register Select = 0 - Data register Software Examples Read Keyboard Poll keyboard Status Check keyboard for CTRL-C VHDL Entity

• VHDL Code
• Wrapper for PS/2 keyboard interfaces
• PS/2 to ASCII conversion

• Value = 0x00, No data present
• Value = 0x01, Data present

• ASCII Data

• Returns keyboard ASCII character in Reg0
• Destroys Reg1

RDKBD	JSR	WTKBRX		WAIT FOR KBD RX CHAR
	IOR	0X01	0X0D	READ KBD CHAR
	RTS			
WTKBRX	IOR	0X00	0X0C	READ KBD STATUS
	ARI	0X00	0X01	RX RDY BIT
	BEZ	WTKBRX		LOOP UNTIL CHAR PRESENT
	RTS			

• Returns keyboard status in Reg0
  • 0x00 = No char
  • 0x01 - Char present

POLLKBD	IOR	0X00	0X0C
	RTS		

• Returns CTRL-c Status
  • 0x00 - No key pressed or not Ctrl-C key
  • 0x01 - CTRL-C was pressed

CHKCTLC	IOR	0X01	0X0C	READ KBD STATUS
	CMP	0x01	0X00	
	BEQ	DONCTLC		KEY WAS NOT PRESSED
SKPCTLC	IOR	0X00	0X0D	READ KBD DATA
	CMP	0X00	0X03	IS CTRL-C
	BNE	DONCTLC		
	LRI	0X00	0X01	RETURNS 1 IF CTRL-C
	JMP	EXITCTLC		
DONCTLC	LRI	0X00	0X00	
EXITCTLC	RTS			

ENTITY Wrap_Keyboard IS
port (
  i_CLOCK_50 : IN  STD_LOGIC; -- input clock
  i_n_reset  : IN  STD_LOGIC; -- 
  i_kbCS     : IN  STD_LOGIC; -- 
  i_RegSel   : IN  STD_LOGIC; -- address
  i_rd_Kbd   : IN  STD_LOGIC; --
  i_ps2_clk  : IN  STD_LOGIC; --
  i_ps2_data : IN  STD_LOGIC; --
  o_kbdDat   : OUT STD_LOGIC_vector(7 downto 0));
end Wrap_Keyboard;