EP7311 datasheet(9/58 Pages) CIRRUS

9 / 58 page

DS506F1

©Copyright Cirrus Logic, Inc. 2005

EP7311

High-Performance, Low-Power System on Chip

64-Keypad Interface

Matrix keyboards and keypads can be easily read by the

EP7311. A dedicated 8-bit column driver output generates

strobes for each keyboard column signal. The pins of Port A,

when configured as inputs, can be selectively OR'ed together

to provide a keyboard interrupt that is capable of waking the

system from a STANDBY or IDLE state.

•

Column outputs can be individually set high with the

remaining bits left at high-impedance

•

Column outputs can be driven all-low, all-high, or all-high-

impedance

•

Keyboard interrupt driven by OR'ing together all Port A

bits

•

Keyboard interrupt can be used to wake up the system

•8

×8 keyboard matrix usable with no external logic, extra

keys can be added with minimal glue logic

Interrupt Controller

When unexpected events arise during the execution of a

program (i.e., interrupt or memory fault) an exception is

usually generated. When these exceptions occur at the same

time, a fixed priority system determines the order in which

they are handled. The EP7311 interrupt controller has two

interrupt types: interrupt request (IRQ) and fast interrupt

request (FIQ). The interrupt controller has the ability to control

interrupts from 22 different FIQ and IRQ sources.

•

Supports 22 interrupts from a variety of sources (such as

UARTs, SSI1, and key matrix.)

•

Routes interrupt sources to the ARM720T’s IRQ or FIQ

(Fast IRQ) inputs

•

Five dedicated off-chip interrupt lines operate as level

sensitive interrupts

Note:

Pins are multiplexed. See Table S on page 11 for more

information.

Real-Time Clock

The EP7311 contains a 32-bit Real Time Clock (RTC) that can

be written to and read from in the same manner as the timer

counters. It also contains a 32-bit output match register which

can be programmed to generate an interrupt.

•

Driven by an external 32.768 kHz crystal oscillator

PLL and Clocking

•

Processor and Peripheral Clocks operate from a single

3.6864 MHz crystal or external 13 MHz clock

•

Programmable clock speeds allow the peripheral bus to run

at 18 MHz when the processor is set to 18 MHz and at

36 MHz when the processor is set to 36, 49 or 74 MHz

Pin Mnemonic

I/O

Pin Description

COL[7:0]

Keyboard scanner column drive

Table J. Keypad Interface Pin Assignments

Pin Mnemonic

I/O

Pin Description

nEINT[2:1]

External interrupt

EINT[3]

External interrupt

nEXTFIQ

External Fast Interrupt input

nMEDCHG/nBROM

(Note)

Media change interrupt input

Table K. Interrupt Controller Pin Assignments

Pin Mnemonic

Pin Description

RTCIN

Real-Time Clock Oscillator Input

RTCOUT

Real-Time Clock Oscillator Output

VDDRTC

Real-Time Clock Oscillator Power

VSSRTC

Real-Time Clock Oscillator Ground

Table L. Real-Time Clock Pin Assignments

Pin Mnemonic

Pin Description

MOSCIN

Main Oscillator Input

MOSCOUT

Main Oscillator Output

VDDOSC

Main Oscillator Power

VSSOSC

Main Oscillator Ground

Table M. PLL and Clocking Pin Assignments

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