EP7312-IV-90 datasheet(9/64 Pages) CIRRUS

Part #	EP7312-IV-90

Description	HIGH-PERFORMANCE, LOW-POWER SYSTEM ON CHIP WITH SDRAM AND ENHANCED DIGITAL AUDIO INTERFACE

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Manufacturer	CIRRUS [Cirrus Logic]

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DS508PP5

©Copyright Cirrus Logic, Inc. 2003

9

EP7312

High-Performance, Low-Power System on Chip

64-Key Keypad Interface

Matrix keyboards and keypads can be easily read by the

EP7312. 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. The Keypad Interface has these

features:

• 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

Abits

• 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

Table 10 shows the Keypad Interface Pin Assignments.

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 EP7312 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. The Interrupt controller

has these features:

• Supports 22 interrupts from a variety of sources (such

as UARTs, SSI1, and key matrix.)

• Routesinterrupt sourcestothe ARM720T’sIRQ or

FIQ (Fast IRQ) inputs

• Five dedicated off-chip interrupt lines operate as level

sensitive interrupts

Table 11 shows the interrupt controller pin assignments.

.

Note:

Pins are multiplexed. See Table 19onpage11 for

more information.

Real-Time Clock

The EP7312 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

Table 12 shows the Real-Time Clock pin assignments.

PLL and Clocking

The EP7312 processor and peripheral clocks have these

features:

• 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, and at 45 MHz when the processor is set to

90 MHz.

Table 13 shows the PLL and clocking pin assignments.

Table 10. Keypad Interface Pin Assignments

Pin Mnemonic

I/O

Pin Description

COL[7:0]

O

Keyboard scanner column drive

Table 11. Interrupt Controller Pin Assignments

Pin Mnemonic

I/O

Pin Description

nEINT[2:1]

I

External interrupt

EINT[3]

I

External interrupt

nEXTFIQ

I

External Fast Interrupt input

nMEDCHG/nBROM

(Note)

I

Media change interrupt input

Table 12. Real-Time Clock 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 13. PLL and Clocking Pin Assignments

Pin Mnemonic

Pin Description

MOSCIN

Main Oscillator Input

MOSCOUT

Main Oscillator Output

VDDOSC

Main Oscillator Power

VSSOSC

Main Oscillator Ground

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