mc9s12q128 Freescale Semiconductor, Inc, mc9s12q128 Datasheet - Page 285

• Manufacturer Part Number: mc9s12q128
• Description: Hcs12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

writes (0x0055 or 0x00AA) to the ARMCOP register must occur in the last 25% of the selected time-out
period. A premature write the CRG will immediately generate a reset.
As soon as the reset sequence is completed the reset generator checks the reset condition. If no clock
monitor failure is indicated and the latched state of the COP timeout is true, processing begins by fetching
the COP vector.
9.5.3
The on-chip voltage regulator detects when V
on reset or low voltage reset or both. As soon as a power-on reset or low voltage reset is triggered the CRG
performs a quality check on the incoming clock signal. As soon as clock quality check indicates a valid
oscillator clock signal the reset sequence starts using the oscillator clock. If after 50 check windows the
clock quality check indicated a non-valid oscillator clock the reset sequence starts using self-clock mode.
Figure 9-26
and when the RESET pin is held low.
Freescale Semiconductor
Power-On Reset, Low Voltage Reset
and
Figure 9-27
Internal RESET
RESET
Internal POR
Internal RESET
RESET
Internal POR
Figure 9-26. RESET Pin Tied to V
show the power-up sequence for cases when the RESET pin is tied to V
Figure 9-27. RESET Pin Held Low Externally
DD
MC9S12Q128
Clock Quality Check
(no Self-Clock Mode)
Clock Quality Check
(no Self-Clock Mode)
to the MCU has reached a certain level and asserts power-
Rev 1.09
128 SYSCLK
) (
) (
128 SYSCLK
) (
) (
) (
) (
Chapter 9 Clocks and Reset Generator (CRGV4) Block Description
64 SYSCLK
DD
64 SYSCLK
(by a Pull-Up Resistor)
DD
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