MC68HC08AZ16 Datasheet, PDF (80/527 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Power-on reset
System Integration Module (SIM)
Reset and system initialization
The COP reset is asynchronous to the bus clock.
ILLEGAL ADDRESS RST
ILLEGAL OPCODE RST
COPRST
LVI
POR
INTERNAL RESET
Figure 5. Sources of internal reset
The active reset feature allows the part to issue a reset to peripherals
and other chips within a system built around the MCU.
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
external reset pin (RST) is held low while the SIM counter counts out
4096 CGMXCLK cycles. 64 CGMXCLK 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:
• A POR pulse is generated
• The internal reset signal is asserted
• The SIM enables CGMOUT
• Internal clocks to the CPU and modules are held inactive for 4096
CGMXCLK cycles to allow the oscillator to stabilize
• The RST pin is driven low during the oscillator stabilization time
• The POR bit of the SIM reset status register (SRSR) is set and all
other bits in the register are cleared
9-sim
MOTOROLA
System Integration Module (SIM)
MC68HC08AZ32
79