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ADSP-2187LKSTZ-2102 Arkusz danych(PDF) 6 Page - Analog Devices |
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ADSP-2187LKSTZ-2102 Arkusz danych(HTML) 6 Page - Analog Devices |
6 / 48 page Rev. C | Page 6 of 48 | January 2008 ADSP-2184L/ADSP-2185L/ADSP-2186L/ADSP-2187L Individual interrupt requests are logically AND’ed with the bits in IMASK; the highest priority unmasked interrupt is then selected. The power-down interrupt is nonmaskable. ADSP-218xL series members mask all interrupts for one instruction cycle following the execution of an instruction that modifies the IMASK register. This does not affect serial port autobuffering or DMA transfers. The interrupt control register, ICNTL, controls interrupt nest- ing and defines the IRQ0, IRQ1, and IRQ2 external interrupts to be either edge- or level-sensitive. The IRQE pin is an external edge-sensitive interrupt and can be forced and cleared. The IRQL0 and IRQL1 pins are external level sensitive interrupts. The IFC register is a write-only register used to force and clear interrupts. On-chip stacks preserve the processor status and are automatically maintained during interrupt handling. The stacks are 12 levels deep to allow interrupt, loop, and subroutine nest- ing. The following instructions allow global enable or disable servicing of the interrupts (including power-down), regardless of the state of IMASK: ENA INTS; DIS INTS; Disabling the interrupts does not affect serial port autobuffering or DMA. When the processor is reset, interrupt servicing is enabled. LOW POWER OPERATION ADSP-218xL series members have three low-power modes that significantly reduce the power dissipation when the device oper- ates under standby conditions. These modes are: • Power-Down •Idle • Slow Idle The CLKOUT pin may also be disabled to reduce external power dissipation. Power-Down ADSP-218xL series members have a low-power feature that lets the processor enter a very low-power dormant state through hardware or software control. Following is a brief list of power- down features. Refer to the ADSP-218x DSP Hardware Refer- ence, “System Interface” chapter, for detailed information about the power-down feature. • Quick recovery from power-down. The processor begins executing instructions in as few as 400 CLKIN cycles. • Support for an externally generated TTL or CMOS proces- sor clock. The external clock can continue running during power-down without affecting the lowest power rating and 400 CLKIN cycle recovery. • Support for crystal operation includes disabling the oscilla- tor to save power (the processor automatically waits approximately 4096 CLKIN cycles for the crystal oscillator to start or stabilize), and letting the oscillator run to allow 400 CLKIN cycle start-up. • Power-down is initiated by either the power-down pin (PWD) or the software power-down force bit. Interrupt support allows an unlimited number of instructions to be executed before optionally powering down. The power- down interrupt also can be used as a nonmaskable, edge- sensitive interrupt. • Context clear/save control allows the processor to continue where it left off or start with a clean context when leaving the power-down state. •The RESET pin also can be used to terminate power-down. • Power-down acknowledge pin (PWDACK) indicates when the processor has entered power-down. Idle When the ADSP-218xL is in the Idle Mode, the processor waits indefinitely in a low-power state until an interrupt occurs. When an unmasked interrupt occurs, it is serviced; execution then continues with the instruction following the IDLE instruc- tion. In Idle Mode IDMA, BDMA, and autobuffer cycle steals still occur. Slow Idle The IDLE instruction is enhanced on ADSP-218xL series mem- bers to let the processor’s internal clock signal be slowed, further reducing power consumption. The reduced clock frequency, a programmable fraction of the normal clock rate, is specified by a selectable divisor given in the IDLE instruction. The format of the instruction is: IDLE (n); where n = 16, 32, 64, or 128. This instruction keeps the proces- sor fully functional, but operating at the slower clock rate. While it is in this state, the processor’s other internal clock signals, such as SCLK, CLKOUT, and timer clock, are reduced by the same ratio. The default form of the instruction, when no clock divisor is given, is the standard IDLE instruction. When the IDLE (n) instruction is used, it effectively slows down the processor’s internal clock and thus its response time to incoming interrupts. The one-cycle response time of the stan- dard idle state is increased by n, the clock divisor. When an enabled interrupt is received, ADSP-218xL series members remain in the idle state for up to a maximum of n processor cycles (n = 16, 32, 64, or 128) before resuming normal operation. When the IDLE (n) instruction is used in systems that have an externally generated serial clock (SCLK), the serial clock rate may be faster than the processor’s reduced internal clock rate. Under these conditions, interrupts must not be generated at a |
Podobny numer części - ADSP-2187LKSTZ-2102 |
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Podobny opis - ADSP-2187LKSTZ-2102 |
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