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UM10326
NXP Semiconductors
Chapter 1: LPC32x0 Introductory information
• For input/output pins, both the programmed output state and the actual pin state can
be read.
• There are a total of 12 general purpose inputs, 24 general purpose outputs, and 38
general purpose input/outputs.
• Additionally, 13 SDRAM data lines may be used as GPIOs if a 16-bit SDRAM
interface is used (rather than a 32-bit interface).
14. Other Peripherals
In addition to the Serial Communication peripherals and GPIO there are many general
purpose peripherals available in the LPC32x0. Here is a list of the remaining peripherals
on the LPC32x0.
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Keyboard Scanner
10-Bit Analog-to-Digital-Converter
Real-Time Clock
Millisecond Timer
A High-speed Timer
4 General Purpose 32-Bit Timer/External Event Counters
2 simple Pulse-Width Modulators
2 Versatile Pulse-Width Modulators
A short functional description of each of these peripherals is provided in the following
sections.
14.1 Keyboard Scanner
The keyboard scanner function can automatically scan a keyboard of up to 64 keys in an
8 × 8 matrix. In operation, the keyboard scanner’s internal state machine will normally be
in an idle state, with all KEY_ROW[n] pins set high, waiting for a change in the column
inputs to indicate that one or more keys have been pressed.
When a keypress is detected, the matrix is scanned by setting one output pin high at a
time and reading the column inputs. After de-bouncing, the keypad state is stored and an
interrupt is generated. The keypad is then continuously scanned waiting for ‘extra key
pressed’ or ‘key released’. Any new keypad state is scanned and stored into the matrix
registers followed by a new interrupt request to the interrupt controller. It is possible to
detect and separate up to 64 multiple keys pressed.
Features
• Supports up to 64 keys in 8 × 8 matrix.
• Programmable debounce period.
• A key press can wake up the CPU from Stop mode.
UM10326_1
User manual
© NXP B.V. 2009. All rights reserved.
Rev. 1 — 18 February 2009
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