Z8F4822AR020SG Datasheet, PDF (200/323 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F64xx Series
Product Specification
180
Option Bits
Option bits allow user configuration of certain aspects of the Z8 Encore! XP F64xx Series
operation. The feature configuration data is stored in the Flash memory and read during
Reset. The features available for control via the option bits are:
• Watchdog Timer time-out response selection–interrupt or Reset
• Watchdog Timer enabled at Reset
• The ability to prevent unwanted read access to user code in Flash memory
• The ability to prevent accidental programming and erasure of the user code in Flash
memory
• Voltage Brown-Out configuration is always enabled or disabled during STOP Mode to
reduce STOP Mode power consumption
• Oscillator mode selection for high-, medium-, and low-power crystal oscillators or an
external RC oscillator
Operation
This section describes the type and configuration of the programmable Flash option bits.
Option Bit Configuration By Reset
Each time the option bits are programmed or erased, the device must be Reset for the
change to take place. During any reset operation (System Reset, Reset, or Stop Mode
Recovery), the option bits are automatically read from the Flash memory and written to
Option Configuration registers. The Option Configuration registers control operation of
the devices within the Z8 Encore! XP F64xx Series. Option bit control is established
before the device exits Reset and the eZ8 CPU begins code execution. The Option Config-
uration registers are not part of the Register File and are not accessible for read or write
access.
Option Bit Address Space
The first two bytes of Flash memory at addresses 0000H (see Table 99) and 0001H (see
Table 100) are reserved for the user option bits. The byte at Flash memory address 0000H
configures user options. The byte at Flash memory address 0001H is reserved for future
use and must remain unprogrammed.
PS019924-0113
PRELIMINARY
Option Bits