Z8F082A28100KIT ZILOG [Zilog, Inc.], Z8F082A28100KIT Datasheet - Page 179

• Manufacturer Part Number: Z8F082A28100KIT
• Description: Z8 Encore XP-R F08xA Series with eXtended Peripherals
• Manufacturer: ZILOG [Zilog, Inc.]

PS024705-0405
Clock Source
Internal Precision
RC Oscillator
External Crystal/
Resonator
External RC
Oscillator
External Clock
Drive
Internal Watchdog
Timer Oscillator
Caution:
OSC Control Register Unlocking/Locking
To write the oscillator control register, unlock it by making two writes to the OSCCTL
register with the values
changes the value of the actual register and returns the register to a locked state. Any other
sequence of oscillator control register writes has no effect. The values written to unlock
the register must be ordered correctly, but are not necessarily consecutive. It is possible to
write to or read from other registers within the unlocking/locking operation.
Unintentional accesses to the oscillator control register can actually stop the chip by
switching to a non-functioning oscillator. To prevent this condition, the oscillator con-
trol block employs a register unlocking/locking scheme.
Characteristics
• 32.8KHz or 5.53MHz
• ± 4% accuracy when trimmed
• No external components required
• 32KHz to 20MHz
• Very high accuracy (dependent on
• Requires external components
• 32KHz to 4MHz
• Accuracy dependent on external
• 0 to 20MHz
• Accuracy dependent on external clock
• 10KHz nominal
• ± 40% accuracy; no external
• Low power consumption
crystal or resonator used)
components
source
components required
Table 101. Oscillator Configuration and Selection
E7H
P R E L I M I N A R Y
followed by
18H
. A third write to the OSCCTL register
Required Setup
• Unlock and write Oscillator Control
• Configure Flash option bits for correct
• Unlock and write OSCCTL to enable
• Configure Flash option bits for correct
• Unlock and write OSCCTL to enable
• Write GPIO registers to configure PB3
• Unlock and write OSCCTL to select
• Apply external clock signal to GPIO
• Enable WDT if not enabled and wait
• Unlock and write Oscillator Control
Register (OSCCTL) to enable and
select oscillator at either 5.53MHz or
32.8KHz
external oscillator mode
crystal oscillator, wait for it to stabilize
and select as system clock (if the
XTLDIS option bit has been de-
asserted, no waiting is required)
external oscillator mode
crystal oscillator and select as system
clock
pin for external clock function
external system clock
until WDT Oscillator is operating.
Register (OSCCTL) to enable and
select oscillator
Z8 Encore! XP
Product Specification
®
F08xA Series
Oscillator Control
161