MC68HC711PH8 Motorola, MC68HC711PH8 Datasheet - Page 38

• Manufacturer Part Number: MC68HC711PH8
• Description: High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit
• Manufacturer: Motorola

2
2.6
The IRQ input provides a means of applying asynchronous interrupt requests to the MCU. Either
falling edge sensitive triggering or level sensitive triggering is program selectable (OPTION
register). IRQ is always configured to level sensitive triggering at reset.
Note:
2.7
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-sensitive, it can be connected to a
multiple-source wired-OR network with an external pull-up resistor to V
a power loss detect interrupt.
Whenever XIRQ or IRQ is used with multiple interrupt sources (IRQ must be configured for level
sensitive operation if there is more than one source of IRQ interrupt), each source must drive the
interrupt input with an open-drain type of driver to avoid contention between outputs. There should
be a single pull-up resistor near the MCU interrupt input pin (typically 4.7 k ). There must also be
an interlock mechanism at each interrupt source so that the source holds the interrupt line low until
the MCU recognizes and acknowledges the interrupt request. If one or more interrupt source is
still pending after the MCU services a request, the interrupt line will still be held low and the MCU
will be interrupted again as soon as the interrupt mask bit in the MCU is cleared (normally upon
return from an interrupt). Refer to Section 10.
On the MC68HC711PH8, the VPPE pin is used to input the external EPROM programming
voltage, which must be present during EPROM programming.
MOTOROLA
2-12
Connect an external pull-up resistor, typically 4.7 k , to V
sensitive wired-OR configuration. See also Section 2.7.
Interrupt request (IRQ)
Nonmaskable interrupt (XIRQ/ VPPE )
PIN DESCRIPTIONS
DD
when IRQ is used in a level
DD
. XIRQ is often used as
MC68HC11PH8
TPG