mc68hc908qz16 Freescale Semiconductor, Inc, mc68hc908qz16 Datasheet - Page 170

• Manufacturer Part Number: mc68hc908qz16
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Resets and Interrupts
14.2.3.1 Power-On Reset (POR)
A power-on reset (POR) is an internal reset caused by a positive transition on the V
POR must go below V
not a brown-out detector, low-voltage detector, or glitch detector.
A power-on reset:
14.2.3.2 Computer Operating Properly (COP) Reset
A computer operating properly (COP) reset is an internal reset caused by an overflow of the COP counter.
A COP reset sets the COP bit in the SIM reset status register.
To clear the COP counter and prevent a COP reset, write any value to the COP control register at location
$FFFF.
14.2.3.3 Low-Voltage Inhibit (LVI) Reset
A low-voltage inhibit (LVI) reset is an internal reset caused by a drop in the power supply voltage to the
LVI
An LVI reset:
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TRIPF
Holds the clocks to the central processor unit (CPU) and modules inactive for an oscillator
stabilization delay of 4096 CGMXCLK cycles
Drives the RST pin low during the oscillator stabilization delay
Releases the RST pin 32 CGMXCLK cycles after the oscillator stabilization delay
Releases the CPU to begin the reset vector sequence 64 CGMXCLK cycles after the oscillator
stabilization delay
Sets the POR and LVI bits in the SIM reset status register and clears all other bits in the register
Holds the clocks to the CPU and modules inactive for an oscillator stabilization delay of 4096
CGMXCLK cycles after the power supply voltage rises to the LVI
Drives the RST pin low for as long as V
stabilization delay
Releases the RST pin 32 CGMXCLK cycles after the oscillator stabilization delay
Releases the CPU to begin the reset vector sequence 64 CGMXCLK cycles after the oscillator
stabilization delay
Sets the LVI bit in the SIM reset status register
voltage.
1. PORRST is an internally generated power-on reset pulse.
PORRST
CGMXCLK
CGMOUT
RST PIN
OSC1
(1)
POR
to reset the MCU. This distinguishes between a reset and a POR. The POR is
MC68HC908GZ16 • MC68HC908GZ8 Data Sheet, Rev. 4
Figure 14-1. Power-On Reset Recovery
CYCLES
4096
CYCLES
32
DD
is below the LVI
TRIPR
voltage and during the oscillator
TRIPR
voltage
Freescale Semiconductor
DD
pin. V
DD
at the