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EP7312-CR-90 Datasheet(PDF) 9 Page - Cirrus Logic |
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EP7312-CR-90 Datasheet(HTML) 9 Page - Cirrus Logic |
9 / 64 page DS508F1 ©Copyright Cirrus Logic, Inc. 2005 (All Rights Reserved) 9 EP7312 High-Performance, Low-Power System on Chip 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 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 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.) • 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 11 shows the interrupt controller pin assignments. . Note: Pins are multiplexed. See Table 19 on page 11 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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