lpc3240 NXP Semiconductors, lpc3240 Datasheet - Page 38

• Manufacturer Part Number: lpc3240
• Description: 16/32-bit Arm Microcontrollers; Hardware ?oating-point Coprocessor, Usb On-the-go, And Emc Memory Interface
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC3220_30_40_50_1
Preliminary data sheet
7.9.2.1 Features
7.9.3.1 Features
7.9.2 Keyboard scanner
7.9.3 Touch screen controller and 10-bit ADC
7.9.4 Real-Time Clock (RTC) and battery RAM
The keyboard scanner function can automatically scan a keyboard of up to 64 keys in an
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in an idle state, with all KEY_ROWn 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.
The LPC3220/30/40/50 microcontrollers includes Touch Screen Controller (TSC)
hardware, which automatically measures and determines the X and Y coordinates where
a touch screen is pressed. In addition, the TSC can measure an analog input signal on the
AUX_IN pin.
Optionally, the TSC can operate as an Analog-to-Digital Converter (ADC). The ADC
supports three channels and uses 10-bit successive approximation to produce results
with a resolution of 10 bits in 11 clock cycles.
The analog portion of the ADC has its own power supply to enhance the low noise
characteristics of the converter. This voltage is only supplied internally when the core has
voltage. However, the ADC block is not affected by any difference in ramp-up time for
VDD_AD and VDD_CORE voltage supplies.
The RTC runs at 32768 Hz using a very low power oscillator. The RTC counts seconds
and can generate alarm interrupts that can wake up the device from Stop mode. The RTC
clock can also clock the 397x PLL, the Millisecond Timer, the ADC, the Keyboard Scanner
and the PWMs. The RTC up-counter value represents a number of seconds elapsed since
second 0, which is an application determined time. The RTC counter will reach maximum
value after about 136 years. The RTC down-counter is initiated with all ones.
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8 matrix. In operation, the keyboard scanner’s internal state machine will normally be
Supports up to 64 keys in 8
Programmable de-bounce period.
A key press can wake up the CPU from Stop mode.
Measurement range of 0 V to VDD_AD (nominally 3.3 V).
Low noise ADC.
10-bit resolution.
Three input channels.
Uses 32 kHz RTC clock or peripheral clock.
Rev. 01 — 6 February 2009
8 matrix.
LPC3220/30/40/50
16/32-bit ARM microcontrollers
© NXP B.V. 2009. All rights reserved.
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