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.
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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
.
Pin Mnemonic
nEINT[2:1]
EINT[3]
nEXTFIQ
nMEDCHG/nBROM
(Note)
I/O
I
I
I
I
Pin Description
External interrupt
External interrupt
External Fast Interrupt input
Media change interrupt input
Table K. Interrupt Controller Pin Assignments
Note:
Pins are multiplexed. See
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
Pin Mnemonic
COL[7:0]
I/O
O
Pin Description
Keyboard scanner column drive
Pin Mnemonic
RTCIN
RTCOUT
VDDRTC
VSSRTC
Pin Description
Real-Time Clock Oscillator Input
Real-Time Clock Oscillator Output
Real-Time Clock Oscillator Power
Real-Time Clock Oscillator Ground
Table J. 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 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.
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•
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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
Table L. Real-Time Clock Pin Assignments
PLL and Clocking
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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
MOSCIN
MOSCOUT
VDDOSC
VSSOSC
Pin Description
Main Oscillator Input
Main Oscillator Output
Main Oscillator Power
Main Oscillator Ground
Table M. PLL and Clocking Pin Assignments
DS506F1
©
Copyright Cirrus Logic, Inc. 2005
(All Rights Reserved)
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