mc9s12e256 Freescale Semiconductor, Inc, mc9s12e256 Datasheet - Page 191

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

Freescale Semiconductor
CME
0
1
1
SCME
X
0
1
SCMIE
X
X
0
Clock failure -->
Clock failure -->
Clock failure -->
Scenario 1: OSCCLK recovers prior to exiting Wait Mode.
– CM no longer indicates a failure,
Some time later either a wakeup interrupt occurs (no SCM interrupt)
or an External Reset is applied.
Scenario 2: OSCCLK does not recover prior to exiting Wait Mode.
Some time later either a wakeup interrupt occurs (no SCM interrupt)
No action, clock loss not detected.
CRG performs Clock Monitor Reset immediately
– MCU remains in Wait Mode,
– VREG enabled,
– PLL enabled,
– SCM activated,
– Start Clock Quality Check,
– Set SCMIF interrupt flag.
Some time later OSCCLK recovers.
– 4096 OSCCLK cycles later Clock Quality Check indicates clock o.k.,
– SCM deactivated,
– PLL disabled depending on PLLWAI,
– VREG remains enabled (never gets disabled in Wait Mode).
– MCU remains in Wait Mode.
– Exit Wait Mode using OSCCLK as system clock (SYSCLK),
– Continue normal operation.
– Exit Wait Mode using OSCCLK as system clock,
– Start reset sequence.
– MCU remains in Wait Mode,
– VREG enabled,
– PLL enabled,
– SCM activated,
– Start Clock Quality Check,
– Set SCMIF interrupt flag,
– Keep performing Clock Quality Checks (could continue infinitely)
– Exit Wait Mode in SCM using PLL clock (f
– Continue to perform additional Clock Quality Checks until OSCCLK
or an External RESET is applied.
– Exit Wait Mode in SCM using PLL clock (f
– Start reset sequence,
– Continue to perform additional Clock Quality Checks until OSCCLK
Table 4-11. Outcome of Clock Loss in Wait Mode
is o.k. again.
is o.k.again.
while in Wait Mode.
MC9S12E256 Data Sheet, Rev. 1.08
CRG Actions
SCM
SCM
Chapter 4 Clocks and Reset Generator (CRGV4)
) as system clock,
) as system clock,
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