z8f0813 ZiLOG Semiconductor, z8f0813 Datasheet - Page 143

• Manufacturer Part Number: z8f0813
• Description: High-performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

PS024314-0308
Caution:
Flash Operation Timing Using the Flash Frequency Registers
Flash Code Protection Against External Access
Flash Code Protection Against Accidental Program and Erasure
Before performing either a program or erase operation on Flash memory, you must first
configure the Flash Frequency High and Low Byte registers. The Flash Frequency regis-
ters allow programming and erasing of the Flash with system clock frequencies ranging
from 32 kHz (32768 Hz) through 20 MHz.
The Flash Frequency High and Low Byte registers combine to form a 16-bit value,
FFREQ, to control timing for Flash program and erase operations. The 16-bit binary Flash
Frequency value must contain the system clock frequency (in kHz). This value is
calculated using the following equation:
The user code contained within the Flash memory can be protected against external access
with the On-Chip Debugger. Programming the FRP Flash Option Bit prevents reading of
the user code with the On-Chip Debugger. For more information, see
page 141 and
Z8 Encore! XP F0823 Series provides several levels of protection against accidental pro-
gram and erasure of the Flash memory contents. This protection is provided by a combina-
tion of the Flash Option bits, the register locking mechanism, the page select redundancy
and the sector level protection control of the Flash Controller.
Flash Code Protection Using the Flash Option Bits
The FRP and FWP Flash Option Bits combine to provide three levels of Flash Program
Memory protection as listed in
page 141.
Flash programming and erasure are not supported for system clock frequencies below
32 kHz (32768 Hz) or above 20 MHz. The Flash Frequency High and Low Byte
registers must be loaded with the correct value to ensure operation of Z8 Encore! XP
F0823 Series devices.
FFREQ[15:0]
On-Chip Debugger
=
System Clock Frequency (Hz)
------------------------------------------------------------------------------ -
Table
on page 151.
1000
78. For more information, see
Z8 Encore! XP
Product Specification
Flash Option Bits
Flash Option Bits
®
F0823 Series
Flash Memory
on
on
®
133