Z8F1680SH020SG Datasheet, PDF (301/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
276
Chapter 21. Flash Option Bits
Programmable Flash option bits allow user configuration of certain aspects of Z8 Encore!
XP F1680 Series MCU operation. The feature configuration data is stored in Flash pro-
gram memory and are read during Reset. The features available for control through the
Flash option bits include:
• Watchdog Timer time-out response selection–interrupt or System Reset
• Watchdog Timer enabled at Reset
• The ability to prevent unwanted read access to user code in Program Memory
• The ability to prevent accidental programming and erasure of all or a portion of the user
code in Program Memory
• VBO configuration-always enabled or disabled during STOP Mode to reduce STOP
Mode power consumption
• LVD voltage threshold selection
• Oscillator mode selection for high, medium and low-power crystal oscillators or an ex-
ternal RC oscillator
• Factory trimming information for the IPO and Temperature Sensor
21.1. Operation
This section describes the types of option bits and their configuration in the Option Con-
figuration registers.
21.1.1. Option Bit Configuration by Reset
Each time the Flash option bits are programmed or erased, the device must be Reset for
the change to take effect. During any Reset operation (System Reset or Stop Mode Recov-
ery), the Flash option bits are automatically read from Flash Program Memory and written
to the Option Configuration registers. These Option Configuration registers control opera-
tion of the devices within the Z8 Encore! XP F1680 Series MCU. Option bit control is
established before the device exits Reset and the eZ8 CPU begins code execution. The
Option Configuration registers are not part of the Register File and are not accessible for
read or write access.
PS025015-1212
PRELIMINARY
Flash Option Bits