UM10375 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
User manual Rev. 3 — 14 June 2011 86 of 368
NXP Semiconductors
UM10375
Chapter 7: LPC13xx I/O configuration
7.3 General description
The IOCON registers control the function (GPIO or peripheral function), the input mode,
and the hysteresis of all PIO pins. In addition, the I
2
C-bus pins can be configured for
different I
2
C-bus modes. If a pin is used as input pin for the ADC, an analog input mode
can be selected.
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 GPIODIR registers determine whether
the pin is configured as an input or output (see Table 150
). For any peripheral function, the
pin direction is controlled automatically depending on the pin’s functionality. The GPIODIR
registers have no effect on 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 pins are pulled up to 2.6 V for
LPC1311/13/42/43 parts and pulled up to 3.3 V for LPC1311/01 and LPC1313/01 parts
(V
DD
= 3.3 V).
Fig 9. Standard I/O pin configuration
PIN
V
DD
ESD
V
SS
ESD
V
DD
weak
pull-up
weak
pull-down
output enable
repeater mode
enable
output
pull-up enable
pull-down enable
data input
analog input
select analog input
002aaf304
pin configured
as digital output
driver
pin configured
as digital input
pin configured
as analog input
To Next Page
Loading...
Need help?
General
