
SMSC DS – LPC47M192 
Page 114 
Rev. 03/30/05 
DATASHEET 
GPIO PIN 
GPIO REGISTER 
PIN# 
PIN NAME 
(Default Func/ 
Alternate Funcs) 
PWR 
WELL 
PCI 
RESET 
VCC 
POR 
VTR 
POR 
REG 
OFFS
ET 
(hex) 
3E 
REG  
PCI 
RESET
VCC 
POR 
VTR 
POR 
SOFT 
RESET 
SMI/PME 
NOTES
28 
GP43/DDRC 
VCC 
In 
In 
In 
GP43 
Note 5 
Note 
5 
- 
- 
- 
0x00 
0x01 
- 
SMI/PME 
1, 5 
92 
94 
95 
96 
GP50/nRI2 
GP51/nDCD2 
GP52/RXD2(IRRX) 
GP53/TXD2 (IRTX) 
VCC 
VCC 
VCC 
VTR 
- 
- 
- 
- 
- 
- 
In 
In 
In 
3F 
40 
41 
42 
GP50 
GP51 
GP52 
GP53 
- 
- 
- 
0x01 
0x01 
0x01 
0x00 
- 
- 
- 
- 
PME 
PME 
PME 
PME 
1 
1 
1 
Out – low 
Out– 
low 
- 
- 
- 
- 
- 
- 
Out– 
low 
In 
In 
In 
In 
In 
In 
0x00 
1, 3 
97 
98 
99 
100 
48 
49 
GP54/nDSR2 
GP55/nRTS2 
GP56/nCTS2 
GP57/nDTR2  
GP60/LED1 
GP61/LED2 
VCC 
VCC 
VCC 
VCC 
VTR 
VTR 
- 
- 
- 
- 
- 
- 
43 
44 
45 
46 
47 
48 
GP54 
GP55 
GP56 
GP57 
GP60 
GP61 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
0x01 
0x01 
0x01 
0x01 
0x01 
0x01 
- 
- 
- 
- 
- 
- 
SMI/PME 
SMI/PME 
SMI/PME 
SMI/PME 
SMI/PME 
SMI/PME 
1 
1 
1 
1 
1 
1 
Note 1:
 These pins are inputs to VCC and VTR powered logic. 
Note 2:
 The fan control pins (FAN1 and FAN2) come up as outputs and low following a VCC POR and PCI Reset. 
Note 3:
 The IRTX pins (IRTX2/GP35 and GP53/TXD2(IRTX)) are driven low when the part is powered by VTR 
(VCC=0V with VTR=3.3V).  These pins will remain low following a VCC POR until IRTX function is selected 
by setting the activate bit, at which time the pin will reflect the state of the transmit output of the IR block.  It 
will remain low following a VCC POR until GPIO input function is selected, at which time the pin will reflect 
the state of the GPIO data bit.  The GP53/TXD2 (IRTX) pin will remain low following a VCC POR (in 
addition to conditions stated above) until serial port 2 is enabled by setting the activate bit, at which time 
the pin will reflect the state of the transmit output of the Serial Port 2 block. 
Note 4:
 These pins are inputs to VCC powered logic.
Note 5:
 Bits [3:2] (Alternate Function Select bits) of this register are reset (cleared) on VCC POR and PCI Reset 
(and VTR POR). 
7.12.2 DESCRIPTION 
Each GPIO port has a 1-bit data register and an 8-bit configuration control register.  The data register for each GPIO 
port is represented as a bit in one of the 8-bit GPIO DATA Registers, GP1 to GP6.  The bits in these registers reflect 
the value of the associated GPIO pin as follows.  Pin is an input: The bit is the value of the GPIO pin.  Pin is an 
output:  The value written to the bit goes to the GPIO pin.  Latched on read and write.  All of the GPIO registers are 
located in the PME block see “Run Time Register” section.  The GPIO ports with their alternate functions and 
configuration state register addresses are listed in Table 53. 
Table 53 - General Purpose I/O Port Assignments 
QFP 
PIN# 
DEFAULT 
FUNCTION 
ALT. FUNC. 1 
ALT. 
FUNC. 2 
ALT. 
FUNC. 3 
DATA 
REGISTER
1
DATA 
REGISTER 
BIT NO. 
0 
1 
2 
3 
4 
5 
6 
7 
0 
1 
2 
3 
4 
REGISTER 
OFFSET 
(HEX) 
4B 
32 
33 
34 
35 
36 
37 
38 
39 
41 
42 
43 
N/A 
45 
GPIO 
GPIO 
GPIO 
GPIO 
GPIO 
GPIO 
GPIO 
GPIO 
GPIO 
GPIO 
GPIO 
Reserved 
GPIO 
(System 
Option) 
GPIO 
GPIO 
Joystick 1 Button 1 
Joystick 1 Button 2 
Joystick 2 Button 1 
Joystick 2 Button 2 
Joystick 1 X-Axis 
Joystick 1 Y-Axis 
Joystick 2 X-Axis 
Joystick 2 Y-Axis 
P17 
P16 
P12 
GP1 
EETI 
EETI 
46 
47 
MIDI_IN 
MIDI_OUT 
5 
6 
GP2 
4C