MC68HC711D3CFNE2 Datasheet, PDF (16/124 Pages) Freescale Semiconductor, Inc – Power Saving STOP and WAIT Modes

Freescale Semiconductor, Inc.
EXTAL
MCU
4xE
CMOS-COMPATIBLE
EXTERNAL OSCILLATOR
XTAL _NC
EXT EXTAL CONN
Figure 2-5 External Oscillator Connections
EXTAL
FIRST
MCU
XTAL
10 MΩ
25 pF *
4xE
CRYSTAL
25 pF *
220 Ω
EXTAL
SECOND
MCU
NC XTAL
* THIS VALUE INCLUDES ALL STRAY CAPACITANCES.
Figure 2-6 One Crystal Driving Two MCUs
DUAL-MCU XTAL CONN
2.4 E-Clock Output (E)
E is the output connection for the internally generated E clock. The signal from E is
used as a timing reference. The frequency of the E-clock output is one fourth that of
the input frequency at the XTAL and EXTAL pins. When E-clock output is low, an in-
ternal process is taking place. When it is high, data is being accessed. All clocks, in-
cluding the E clock, are halted when the MCU is in STOP mode. The E clock can be
turned off in single-chip modes to reduce the effects of radio frequency interference
(RFI).
2.5 Interrupt Request (IRQ)
The IRQ input provides a means of applying asynchronous interrupt requests to the
MCU. Either negative edge-sensitive triggering or level-sensitive triggering is program
selectable (OPTION register). IRQ is always configured to level-sensitive triggering at
reset. Connect an external pullup resistor, typically 4.7 kΩ, to V_DD when IRQ is used
in a level sensitive wired-OR configuration.
2.6 Non-Maskable Interrupt (XIRQ)
The XIRQ input provides a means of requesting a nonmaskable interrupt after reset
initialization. During reset, the X bit in the condition code register (CCR) is set and any
interrupt is masked until MCU software enables it. Because the XIRQ input is level-
PIN DESCRIPTIONS
2-4
TECHNICAL DATA
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