EP7312-CB-90 CIRRUS [Cirrus Logic], EP7312-CB-90 Datasheet - Page 9

• Manufacturer Part Number: EP7312-CB-90
• Description: HIGH-PERFORMANCE, LOW-POWER SYSTEM ON CHIP WITH SDRAM AND ENHANCED DIGITAL AUDIO INTERFACE
• Manufacturer: CIRRUS [Cirrus Logic]

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
• Column outputs can be driven all-low, all-high, or all-
• Keyboard interrupt driven by OR'ing together all Port
• Keyboard interrupt can be used to wake up the
• 8×8 keyboard matrix usable with no external logic,
Table 10
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
• Routes interrupt sources to the ARM720T’s IRQ or
• Five dedicated off-chip interrupt lines operate as level
Table 11
DS508PP5
COL[7:0]
remaining bits left at high-impedance
high-impedance
A bits
system
extra keys can be added with minimal glue logic
as UARTs, SSI1, and key matrix.)
FIQ (Fast IRQ) inputs
sensitive interrupts
Pin Mnemonic
shows the interrupt controller pin assignments.
shows the Keypad Interface Pin Assignments.
Table 10. Keypad Interface Pin Assignments
I/O
O
Keyboard scanner column drive
Pin Description
©
C opyright Cirrus Logic, Inc. 2003
(All Rights Reserved)
.
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
PLL and Clocking
The EP7312 processor and peripheral clocks have these
features:
• Processor and peripheral clocks operate from a single
• Programmable clock speeds allow the peripheral bus
Table 13
nEINT[2:1]
EINT[3]
nEXTFIQ
nMEDCHG/nBROM
MOSCIN
MOSCOUT
VDDOSC
VSSOSC
Note:
3.6864 MHz crystal or external 13 MHz clock
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.
RTCIN
RTCOUT
VDDRTC
VSSRTC
Pin Mnemonic
Pin Mnemonic
Pin Mnemonic
Table 11. Interrupt Controller Pin Assignments
shows the Real-Time Clock pin assignments.
shows the PLL and clocking pin assignments.
Table 13. PLL and Clocking Pin Assignments
Pins are multiplexed. See
more information.
Table 12. Real-Time Clock Pin Assignments
High-Performance, Low-Power System on Chip
(Note)
Main Oscillator Input
Main Oscillator Output
Main Oscillator Power
Main Oscillator Ground
Real-Time Clock Oscillator Input
Real-Time Clock Oscillator Output
Real-Time Clock Oscillator Power
Real-Time Clock Oscillator Ground
I/O
I
I
I
I
Table 19 on page 11
Pin Description
Pin Description
External interrupt
External interrupt
External Fast Interrupt input
Media change interrupt input
Pin Description
for
EP7312
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