MC68HC705C8ACS

Manufacturer Part NumberMC68HC705C8ACS
ManufacturerFreescale Semiconductor, Inc
MC68HC705C8ACS datasheet
 
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Freescale Semiconductor, Inc.
Resets
5.3.1 Power-On Reset (POR)
A positive transition on the V
The POR is strictly for the power-up condition and cannot be used to
detect drops in power supply voltage.
A 4064 t
active allows the clock generator to stabilize. If the RESET pin is at
logic 0 at the end of 4064 t
until the signal on the RESET pin goes to logic 1.
5.3.2 External Reset
The minimum time required for the MCU to recognize a reset is 1 1/2
t
CYC
as an external reset and not as a COP or clock monitor reset, the RESET
pin must be low for eight t
is sampled. If the pin is still low, an external reset has occurred. If the
input is high, then the MCU assumes that the reset was initiated
internally by either the COP watchdog timer or by the clock monitor. This
method of differentiating between external and internal reset conditions
assumes that the RESET pin will rise to a logic 1 less than two t
its release and that an externally generated reset should stay active for
at least eight t
5.3.3 Programmable and Non-Programmable COP Watchdog Resets
A timeout of a COP watchdog generates a COP reset. A COP watchdog,
once enabled, is part of a software error detection system and must be
cleared periodically to start a new timeout period.
The MC68HC705C8A has two different COP watchdogs for compatibility
with devices such as the MC68HC705C8 and the MC68HC05C4A:
1. Programmable COP watchdog reset
2. Non-programmable COP watchdog
One COP has four programmable timeout periods and the other has a
fixed non-programmable timeout period.
Technical Data
62
pin generates a power-on reset (POR).
DD
(internal clock cycle) delay after the oscillator becomes
CYC
, the MCU remains in the reset condition
CYC
. However, to guarantee that the MCU recognizes an external reset
. After six t
CYC
.
CYC
Resets
For More Information On This Product,
Go to: www.freescale.com
, the input on the RESET pin
CYC
after
CYC
MC68HC705C8A — Rev. 3