MC68HC908KX8 Datasheet, PDF (84/310 Pages) Motorola, Inc – Microcontrollers

System Integration Module (SIM)
6.4.1.1 Power-On Reset
When power is first applied to the MCU, the power-on reset (POR)
module generates a pulse to indicate that power-on has occurred. The
MCU is held in reset while the SIM counter counts out 4096 CGMXCLK
cycles. Another 64 CGMXCLK cycles later, the CPU and memories are
released from reset to allow the reset vector sequence to occur.
At power-on, these 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 stabilization of the internal clock
generator.
• The POR bit of the SIM reset status register (SRSR) is set and all
other bits in the register are cleared.
PORRST
CGMXCLK
CGMOUT
IRST
IAB
4096
CYCLES
64
CYCLES
$FFFE
$FFFF
Figure 6-6. POR Recovery
Technical Data
84
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
System Integration Module (SIM)
MOTOROLA