UM10462 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2016. All rights reserved.
User manual Rev. 5.5 — 21 December 2016 163 of 523
NXP Semiconductors
UM10462
Chapter 9: LPC11U3x/2x/1x GPIO
9.5.3 GPIO port register description
9.5.3.1 GPIO port byte pin registers
Each GPIO pin has a byte register in this address range. Software typically reads and
writes bytes to access individual pins, but can read or write halfwords to sense or set the
state of two pins, and read or write words to sense or set the state of four pins.
9.5.3.2 GPIO port word pin registers
Each GPIO pin has a word register in this address range. 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.
Table 156. GPIO port 0 byte pin registers (B0 to B23, addresses 0x5000 0000 to 0x5000 0018)
bit description
Bit Symbol Description Reset
value
Access
0 PBYTE Read: state of the pin P0_n, regardless of direction, masking,
or alternate function, except that 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 157. GPIO port 1 byte pin registers (B32 to B63, addresses 0x5000 0020 to 0x5000
002F) bit description
Bit Symbol Description Reset
value
Access
0 PBYTE Read: state of the pin P1_n, regardless of direction, masking,
or alternate function, except that 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 158. GPIO port 0 word pin registers (W0 to W23, addresses 0x5000 1000 to 0x5000
1060) bit description
Bit Symbol Description Reset
value
Access
31:0 PWORD Read 0: pin 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
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