UM11029
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User manual
Rev. 1.0 — 16 June 2017
211 of 515
NXP Semiconductors
UM11029
Chapter 12: LPC84x General Purpose I/O (GPIO)
12.5.10 GPIO port direction set registers
Direction bits can be set by writing ones to these registers.
12.5.11 GPIO port direction clear registers
Direction bits can be cleared by writing ones to these write-only registers.
12.5.12 GPIO port direction toggle registers
Direction bits can be set by writing ones to these write-only registers.
12.6 Functional description
12.6.1 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.
•
The state of a single pin can be read in all bits of a byte, halfword, or word from a
Word Pin register.
Table 264. GPIO port direction set register (DIRSET[0:1], address 0xA000 2380 (DIRSET0) to
0xA000 2384 (DIRSET1)) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
DIRSETP Set direction bits (bit 0 = PIOm_0, bit 1 = PIOm_1, ..., bit 31
= PIOm_31). m = port 0 to 1; n = pin 0 to 31 for port 0 and
pin 0 to 21 for port 1.
0 = No operation.
1 = Set direction bit.
0
WO
Table 265. GPIO port direction clear register (DIRCLR[0:1], 0xA000 2400(DIRCLR0) to 0xA000
2404 (DIRCLR1)) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
DIRCLRP
Clear direction bits (bit 0 = PIOm_0,
bit 1 = PIOm_1, ..., bit 31 = PIOm_31). m = port 0 to
1; n = pin 0 to 31 for port 0 and pin 0 to 21 for port 1.
0 = No operation.
1 = Clear direction bit.
NA
WO
Table 266. GPIO port direction toggle register (DIRNOT[0:1], address 0xA000 2480(DIRNOT0)
to 0xA000 2484 (DIRNOT1)) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
DIRNOTP Toggle direction bits (bit 0 = PIOm_0, bit 1 = PIOm_1, ...,
bit 31 = PIOm_31). m = port 0 to 1; n = pin 0 to 31 for port 0
and pin 0 to 21 for port 1.
0 = no operation.
1 = Toggle direction bit.
NA
WO
