LPC47M112 SMSC Corporation, LPC47M112 Datasheet - Page 135

• Manufacturer Part Number: LPC47M112
• Description: ENHANCED SUPER I/O CONTROLLER WITH LPC INTERFACE
• Manufacturer: SMSC Corporation

Enhanced Super I/O Controller with LPC Interface
Datasheet
The game port register is defined below. It is a runtime register located at the address programmed into the base I/O
address (GAME_PORT) in Logical Device 9.
Note:
When the activate bit in Logical Device 9 is cleared, it prevents the base I/O address for the game port from being
decoded.
Game Port Register
Register Location: <GAME_PORT>+0h System I/O Space
Default Value:
Attribute:
Size:
The game port register is a read-only register. However, writing to the game port resets the RC time constant pins
(TIMA, B) to zero. The reset of the time constant pins occur on the “back” edge of the write signal (when the write
signal goes from its active state to its inactive state).The game port read (JOYR) will be an IO read to the address
programmed into the base IO address in Logical Device 9.
The game port write (JOYW) will be an IO write to the address programmed into the base IO address in Logical
Device 9.
Minimum Rise Time
The fastest rise time on the RC constant pins (minimum RC time constant) for the game port is 20usec.
27.1
Bit 2 in the Power Control Register (CR22) is the power control bit for the game port. This bit has the same function
as the activate bit for logical device 9 and shadows the activate bit. The activate bit also shadows the power control
bit 2.
27.2
The LPC47M112 has a reference voltage pin input on pin 44 of the part. This reference voltage can be connected to
either a 5V supply or a 3.3V supply. It is used for the game port.
The reference voltage is used in the game port logic so that the joystick trigger voltage is 2/3 VREF where VREF is
either 5V or 3.3V. This is to preserve joystick compatibility by maintaining the RC time constant reset trigger voltage
of 3.3V (nominal) with VREF=5V (nominal), if required.
SMSC DS – LPC47M112
Register 0x60 is the high byte; 0x61 is the low byte. For example, to set the primary base address to 1234h,
write 12h into 0x60, and 34h into 0x61.
Joystick 2
Button #2
(J2B2)
D7
00h on VTR POR
Read-Only
8-bits
Joystick 2
Button #1
(J2B1)
D6
Joystick 1
Button #2
(J1B2)
D5
Joystick 1
Button #1
(J1B1)
D4
Page 135
Joystick 2
(OUT2B)
Y-Axis
D3
Power Control Register
VREF Pin
Joystick 2
(OUT2A)
X-Axis
D2
Joystick 1
(OUT1B)
Y-Axis
D1
Joystick 1
(OUT1A)
X-Axis
D0
Rev. 02/02/2005