MC68HC11P2 Datasheet, PDF (59/268 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Operating Modes and On-Chip Memory
System initialization
After enabling the A/D power, at least 100µs should be allowed for
system stabilization.
CSEL — Clock select (refer to Analog-to-Digital Converter)
1 = A/D and EEPROM use internal RC clock source (about
1.5 MHz).
0 = A/D and EEPROM use system E clock (must be at least 1MHz).
Selects alternate clock source for on-chip EEPROM and A/D charge
pumps. The on-chip RC clock should be used when the E clock
frequency falls below 1MHz.
IRQE — Configure IRQ for falling edge sensitive operation
1 = Falling edge sensitive operation.
0 = Low level sensitive operation.
DLY — Enable oscillator start-up delay
1 = A delay of approximately 4064 E clock cycles is imposed as the
MCU is started up from the STOP mode.
0 = The oscillator start-up delay coming out of STOP is bypassed
and the MCU resumes processing within about four bus
cycles. A stable external oscillator is required if this option is
selected.
CME — Clock monitor enable (refer to Resets and Interrupts)
1 = Clock monitor enabled.
0 = Clock monitor disabled.
In order to use both STOP and clock monitor, the CME bit should be
set before executing STOP, then set again after recovering from
STOP.
FCME — Force clock monitor enable (refer to Resets and Interrupts)
1 = Clock monitor enabled; cannot be disabled until next reset.
0 = Clock monitor follows the state of the CME bit.
When FCME is set, slow or stopped clocks will cause a clock failure
reset sequence. To utilize STOP mode, FCME should always be
cleared.
CR[1:0] — COP timer rate select bits (refer to Resets and Interrupts)
MC68HC11P2 — Rev 1.0
Operating Modes and On-Chip Memory
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Technical Data