MC705P6ACPE Datasheet, PDF (17/98 Pages) Freescale Semiconductor, Inc – M68HC05 Microcontrollers

Functional Pin Description
1.3.8 TCMP
This pin is the output from the 16-bit timer’s output compare function. It is low after reset. Refer to
Chapter 8 Capture/Compare Timer.
1.3.9 IRQ/V_PP (Maskable Interrupt Request)
This input pin drives the asynchronous interrupt function of the MCU in user mode and provides the V_PP
programming voltage in bootloader mode. The MCU will complete the current instruction being executed
before it responds to the IRQ interrupt request. When the IRQ/V_PP pin is driven low, the event is latched
internally to signify an interrupt has been requested. When the MCU completes its current instruction, the
interrupt latch is tested. If the interrupt latch is set and the interrupt mask bit (I bit) in the condition code
register is clear, the MCU will begin the interrupt sequence.
Depending on the MOR LEVEL bit, the IRQ/V_PP pin will trigger an interrupt on either a negative edge at
the IRQ/V_PP pin and/or while the IRQ/V_PP pin is held in the low state. In either case, the IRQ/V_PP pin must
be held low for at least one t_ILIH time period. If the edge- and level-sensitive mode is selected (LEVEL bit
set), the IRQ/V_PP input pin requires an external resistor connected to V_DD for wired-OR operation. If the
IRQ/V_PP pin is not used, it must be tied to the V_DD supply. The IRQ/V_PP pin input circuitry contains an
internal Schmitt trigger to improve noise immunity. Refer to Chapter 5 Interrupts.
NOTE
If the voltage level applied to the IRQ/V_PP pin exceeds V_DD, it may affect
the MCU’s mode of operation. See Chapter 3 Operating Modes.
MC68HC705P6A Advance Information Data Sheet, Rev. 2.1
Freescale Semiconductor
17