MC908QL4 FREESCALE [Freescale Semiconductor, Inc], MC908QL4 Datasheet - Page 121

• Manufacturer Part Number: MC908QL4
• Description: M68HC08 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

13.4.2.1 Power-On Reset
When power is first applied to the MCU, the power-on reset module (POR) generates a pulse to indicate
that power on has occurred. The SIM counter counts out 4096 BUSCLKX4 cycles. Sixty-four BUSCLKX4
cycles later, the CPU and memories are released from reset to allow the reset vector sequence to occur.
At power on, the following events occur:
See
Freescale Semiconductor
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Figure
A POR pulse is generated.
The internal reset signal is asserted.
The SIM enables the oscillator to drive BUSCLKX4.
Internal clocks to the CPU and modules are held inactive for 4096 BUSCLKX4 cycles to allow
stabilization of the oscillator.
The POR bit of the SIM reset status register (SRSR) is set.
13-6.
BUSCLKX4
ADDRESS
IRST
RST
BUS
Reset Recovery Type
All others
POR/LVI
Figure 13-5. Sources of Internal Reset
ILLEGAL ADDRESS RST
RST PULLED LOW BY MCU
ILLEGAL OPCODE RST
Table 13-2. Reset Recovery Timing
Figure 13-4. Internal Reset Timing
MC68HC908QL4 Data Sheet, Rev. 7
COPRST
32 CYCLES
POR
LVI
Actual Number of Cycles
4163 (4096 + 64 + 3)
INTERNAL RESET
32 CYCLES
67 (64 + 3)
VECTOR HIGH
Reset and System Initialization
121