UM10462
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© NXP B.V. 2016. All rights reserved.
User manual
Rev. 5.5 — 21 December 2016
81 of 523
NXP Semiconductors
UM10462
Chapter 7: LPC11U3x/2x/1x I/O configuration
7.3.1 Pin function
The FUNC bits in the IOCON registers can be set to GPIO (FUNC = 000) or to a
peripheral function. If the pins are GPIO pins, the DIR registers determine whether the pin
is configured as an input or output (see
). For any peripheral function, the
pin direction is controlled automatically depending on the pin’s functionality. The DIR
registers have no effect for peripheral functions.
7.3.2 Pin mode
The MODE bits in the IOCON register allow the selection of on-chip pull-up or pull-down
resistors for each pin or select the repeater mode.
The possible on-chip resistor configurations are pull-up enabled, pull-down enabled, or no
pull-up/pull-down. The default value is pull-up enabled.
The repeater mode enables the pull-up resistor if the pin is at a logic HIGH and enables
the pull-down resistor if the pin is at a logic LOW. This causes the pin to retain its last
known state if it is configured as an input and is not driven externally. The state retention is
The 10 ns glitch filter is available on selected pins only.
Fig 13. Standard I/O pin configuration
PIN
V
DD
V
DD
ESD
V
SS
ESD
strong
pull-up
strong
pull-down
V
DD
weak
pull-up
weak
pull-down
open-drain enable
output enable
repeater mode
enable
pull-up enable
pull-down enable
select data
inverter
data output
data input
select glitch
filter
analog input
select analog input
002aaf695
pin configured
as digital output
driver
pin configured
as digital input
pin configured
as analog input
10 ns RC
GLITCH FILTER