UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
344 of 1269
NXP Semiconductors
UM10503
Chapter 17: LPC43xx GPIO
17.5.3.7 GPIO port set registers
Each GPIO port has one port set register. Output bits can be set by writing ones to these
registers, regardless of MASK registers. Reading from these register returns the port’s
output bits, regardless of pin directions.
17.5.3.8 GPIO port clear registers
Each GPIO port has one output clear register. Output bits can be cleared by writing ones
to these write-only registers, regardless of MASK registers.
17.5.3.9 GPIO port toggle registers
Each GPIO port has one output toggle register. Output bits can be
toggled/inverted/complemented by writing ones to these write-only registers, regardless of
MASK registers.
17.6 Functional description
17.6.1 Reading pin state
Software can read the state of all GPIO pins except those selected for analog input or
output in the “I/O Configuration” logic. A pin does not have to be selected for GPIO in “I/O
Configuration” in order to read its state. There are four ways to read pin state:
•
The state of a single pin can be read with 7 high-order zeros from a Byte Pin register.
Table 205. GPIO port set register (SET, addresses 0x400F 6200 (SET0) to 0x400F 621C
(SET7)) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
SET
Read or set output bits (bit 0 = GPIOn[0], bit 1 =
GPIOn[1], ..., bit 31 = GPIOn[31]).
0 = Read: output bit: write: no operation.
1 = Read: output bit; write: set output bit.
0
R/W
Table 206. GPIO port clear register (CLR, addresses 0x400F 6280 (CLR0) to 0x400F 629C
(CLR7)) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
CLR
Clear output bits (bit 0 = GPIOn[0], bit 1 = GPIOn[1],
..., bit 31 = GPIOn[31]):
0 = No operation.
1 = Clear output bit.
NA
WO
Table 207. GPIO port toggle register (NOT, addresses 0x400F 6300 (NOT0) to 0x400F 632C
(NOT7)) bit description
Bit
Symbol Description
Reset
value
Access
31:0
NOTP0
Toggle output bits (bit 0 = GPIOn[0], bit 1 = GPIOn[1], ..., bit
31 = GPIOn[31]):
0 = no operation.
1 = Toggle output bit.
NA
WO