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8XC196Kx,8XC196Jx,87C196CA microcontroller family user's manual.1995.pdf
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8XC196Kx, Jx, CA USER’S MANUAL

The device enters idle mode after executing the IDLPD #1 instruction. Either an interrupt or a hardware reset will cause the device to exit idle mode. Any enabled interrupt source, either internal or external, can cause the device to exit idle mode. When an interrupt occurs, the CPU clocks restart and the CPU executes the corresponding interrupt service or PTS routine. When the routine is complete, the CPU fetches and then executes the instruction that follows the IDLPD #1 instruction.

NOTE

If enabled, the watchdog timer continues to run in idle mode. The device must be awakened within every 64K state times to clear the WATCHDOG register; otherwise, the timer will reset the device.

To prevent an accidental return to full power, hold the external interrupt pin (EXTINT) low while the device is in idle mode.

14.4POWERDOWN MODE

Powerdown mode places the device into a very low power state by disabling the internal oscillator and clock generators. Internal logic holds the CPU and peripheral clocks at logic zero, which causes the CPU to stop executing instructions, the system bus-control signals to become inactive, the CLKOUT signal to become high, and the peripherals to turn off. Power consumption drops into the microwatt range (refer to the datasheet for exact specifications). ICC is reduced to device leakage. Tables in Appendix B list the values of the pins during powerdown mode (see Table B-8 on page B-20 for the 8XC196Kx, Table B-9 on page B-21 for the 8XC196Jx, or Table B-10 on page B-22 for the 87C196CA). If VCC is maintained above the minimum specification, the spe- cial-function registers (SFRs) and register RAM retain their data.

14.4.1 Enabling and Disabling Powerdown Mode

Setting the PD bit in the chip-configuration register 0 (CCR0.0) enables powerdown mode. Clearing it disables powerdown. CCR0 is loaded from the chip configuration byte (CCB0) when the device is reset.

14-4

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