Z8F1680SH020SG Datasheet, PDF (296/412 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F1680 Series
Product Specification
271
20.2.8. Flash Controller Behavior in Debug Mode
The following changes in behavior of the Flash Controller occur when the Flash Control-
ler is accessed using the On-Chip Debugger:
• The Flash Write Protect option bit is ignored
• The Flash Sector Protect register is ignored for programming and erase operations
• Programming operations are not limited to the page selected in the Page Select Register
• Bits in the Flash Sector Protect register can be written to 1 or 0
• The second write of the Page Select register to unlock the Flash Controller is not nec-
essary
• The Page Select register can be written when the Flash Controller is unlocked
• The Mass Erase command is enabled through the Flash Control Register
Caution: For security reasons, the Flash controller allows only a single page to be opened for
write/erase. When writing multiple Flash pages, the Flash controller must go through
the unlock sequence again to select another page.
20.3. Flash Control Register Definitions
This section defines the features of the following Flash Control registers.
Flash Control Register: see page 271
Flash Status Register: see page 272
Flash Page Select Register: see page 273
Flash Sector Protect Register: see page 274
Flash Frequency High and Low Byte Registers: see page 274
20.3.1. Flash Control Register
The Flash Controller must be unlocked using the Flash Control Register (see Table 134)
before programming or erasing Flash memory. The Flash Controller is unlocked by
writing to the Flash Page Select Register, then 73H 8CH, sequentially, to the Flash Control
Register, and finally again to the Flash Page Select Register with the same value as the
previous write. When the Flash Controller is unlocked, Mass Erase or Page Erase can be
initiated by writing the appropriate command to the FCTL. Erase applies only to the active
page selected in the Flash Page Select Register. Mass Erase is enabled only through the
PS025015-1212
PRELIMINARY
Flash Memory