LPC3240 datasheet(38/73 Pages) NXP

38 / 73 page

LPC3220_30_40_50_1

Preliminary data sheet

Rev. 01 — 6 February 2009

38 of 73

NXP Semiconductors

LPC3220/30/40/50

16/32-bit ARM microcontrollers

7.9.2 Keyboard scanner

The keyboard scanner function can automatically scan a keyboard of up to 64 keys in an

× 8 matrix. In operation, the keyboard scanner’s internal state machine will normally be

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.

7.9.2.1

Features

• Supports up to 64 keys in 8

× 8 matrix.

• Programmable de-bounce period.

• A key press can wake up the CPU from Stop mode.

7.9.3 Touch screen controller and 10-bit ADC

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.

7.9.3.1

Features

• 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.

7.9.4 Real-Time Clock (RTC) and battery RAM

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.

LPC3240 Datasheet(PDF) 38 Page - NXP Semiconductors

LPC3240 Datasheet(HTML) 38 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73

Datasheet Download

Link URL