mc68hc908qf4 Freescale Semiconductor, Inc, mc68hc908qf4 Datasheet - Page 123

• Manufacturer Part Number: mc68hc908qf4
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

14.4.1 External Pin Reset
14.4.2 Active Resets from Internal Sources
MC68HC908QF4 — Rev. 1.0
MOTOROLA
NOTE:
The RST pin circuits include an internal pullup device. Pulling the asynchronous
RST pin low halts all processing. The PIN bit of the SIM reset status register
(SRSR) is set as long as RST is held low for at least the minimum t
Figure 14-4
RSTEN bit is set in the CONFIG1 register.
The RST pin is initially setup as a general-purpose input after a POR. Setting the
RSTEN bit in the CONFIG1 register enables the pin for the reset function. This
section assumes the RSTEN bit is set when describing activity on the RST pin.
All internal reset sources actively pull the RST pin low for 32 BUSCLKX4 cycles to
allow resetting of external peripherals. The internal reset signal IRST continues to
be asserted for an additional 32 cycles (see
caused by an illegal address, illegal opcode, COP time out, LVI, or POR (see
Figure
For POR and LVI resets, the SIM cycles through 4096 BUSCLKX4 cycles during
which the SIM forces the RST pin low. The internal reset signal then follows the
sequence from the falling edge of RST shown in
The COP reset is asynchronous to the bus clock.
The active reset feature allows the part to issue a reset to peripherals and other
chips within a system built around the MCU.
ADDRESS BUS
BUSCLKX4
ADDRESS
BUSCLKX2
IRST
BUS
RST
Freescale Semiconductor, Inc.
14-6).
RST
For More Information On This Product,
shows the relative timing. The RST pin function is only available if the
PC
System Integration Module (SIM)
Go to: www.freescale.com
RST PULLED LOW BY MCU
Figure 14-4. External Reset Timing
Figure 14-5. Internal Reset Timing
32 CYCLES
Figure
Figure
32 CYCLES
14-5). An internal reset can be
System Integration Module (SIM)
VECT H VECT L
Reset and System Initialization
14-5.
VECTOR HIGH
RL
time.
Data Sheet
123