UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
342 of 1269
NXP Semiconductors
UM10503
Chapter 17: LPC43xx GPIO
17.5.3.2 GPIO port word pin registers
Each GPIO pin GPIOn[m] has a word register in this address range. The word pin
registers of GPIO port 0 correspond to registers W0 to W31, the word pin registers of
GPIO port 1 correspond to registers W32 to W63, etc.. Word addresses are reserved for
unused GPIO port pins (see
Any byte, halfword, or word read in this range will be all zeros if the pin is low or all ones if
the pin is high, regardless of direction, masking, or alternate function, except that pins
configured as analog I/O always read as zeros. Any write will clear the pin’s output bit if
the value written is all zeros, else it will set the pin’s output bit.
Remark:
To read the signal on the GPIO input, enable the input buffer in the syscon block
for the corresponding pin (see
17.5.3.3 GPIO port direction registers
Each GPIO port n (n = 0 to 7) has one direction register for configuring the port pins as
inputs or outputs.
Table 199. GPIO port byte pin registers (B, addresses 0x400F 4000 (B0) to 0x400F 00FC
(B255)) bit description
Bit
Symbol Description
Reset
value
Access
0
PBYTE
Read: state of the pin GPIOn[m], regardless of direction,
masking, or alternate function. Pins configured as analog I/O
always read as 0.
Write: loads the pin’s output bit.
ext
R/W
7:1
Reserved (0 on read, ignored on write)
0
-
Table 200. GPIO port word pin registers (W, addresses 0x400F 5000 (W0) to 0x400F 13FC
(W255)) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
PWORD
Read 0: pin GPIOn[m] is LOW.
Write 0: clear output bit.
Read 0xFFFF FFFF: pin is HIGH.
Write any value 0x0000 0001 to 0xFFFF FFFF: set output
bit.
Remark:
Only 0 or 0xFFFF FFFF can be read. Writing any
value other than 0 will set the output bit.
ext
R/W
Table 201. GPIO port direction register (DIR, addresses 0x400F 6000 (DIR0) to 0x400F 601C
(DIR7)) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
DIR
Selects pin direction for pin GPIOn[m] (bit 0 = GPIOn[0], bit
1 = GPIOn[1], ..., bit 31 = GPIOn[31]).
0 = input.
1 = output.
0
R/W