mc9s12e256 Freescale Semiconductor, Inc, mc9s12e256 Datasheet - Page 197

• Manufacturer Part Number: mc9s12e256
• Description: Hcs12 Microcontrollers 16-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Definition.” All reset sources are listed in
Overview (MC9S12E256DGV1)”
The reset sequence is initiated by any of the following events:
Upon detection of any reset event, an internal circuit drives the RESET pin low for 128 SYSCLK cycles
(see
However, the internal reset circuit of the CRGV4 cannot sequence out of current reset condition without a
running SYSCLK. The number of 128 SYSCLK cycles might be increased by n = 3 to 6 additional
SYSCLK cycles depending on the internal synchronization latency. After 128+n SYSCLK cycles the
RESET pin is released. The reset generator of the CRGV4 waits for additional 64 SYSCLK cycles and
then samples the RESET pin to determine the originating source.
fetched.
Freescale Semiconductor
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Figure
Low level is detected at the RESET pin (external reset).
Power on is detected.
Low voltage is detected.
COP watchdog times out.
Clock monitor failure is detected and self-clock mode was disabled (SCME = 0).
4-25). Because entry into reset is asynchronous it does not require a running SYSCLK.
External circuitry connected to the RESET pin should not include a large
capacitance that would interfere with the ability of this signal to rise to a
valid logic 1 within 64 SYSCLK cycles after the low drive is released.
Sampled RESET Pin
(64 Cycles After
Release)
1
1
1
0
COP Watchdog Reset
Clock Monitor Reset
Low Voltage Reset
Power-on Reset
External Reset
Reset Source
for related vector addresses and priorities.
Table 4-14. Reset Vector Selection
Reset Pending
Clock Monitor
MC9S12E256 Data Sheet, Rev. 1.08
Table 4-13. Reset Summary
Table
0
1
0
X
4-13. Refer to
NOTE
PLLCTL (CME=1, SCME=0)
COPCTL (CR[2:0] nonzero)
COP Reset
Pending
X
X
Local Enable
0
1
None
None
None
Chapter 1, “MC9S12E256 Device
POR / LVR / External Reset
Clock Monitor Reset
COP Reset
POR / LVR / External Reset
with rise of RESET pin
Table 4-14
Chapter 4 Clocks and Reset Generator (CRGV4)
Vector Fetch
shows which vector will be
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