z8f083a ZiLOG Semiconductor, z8f083a Datasheet - Page 122

• Manufacturer Part Number: z8f083a
• Description: High-performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

.
PS026308-1207
Caution:
Flash Operation Timing Using the Flash Frequency Registers
Flash Code Protection Against External Access
Flash Code Protection Against Accidental Program and Erasure
FFREQ[15:0]
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 registers
allow programming and erasing of the Flash with system clock frequencies ranging from
10 kHz to 20 MHz.
The Flash frequency high and low byte registers combine to form a 16-bit value, FFREQ,
to control the 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 is protected against external access by
using the On-Chip Debugger. Programming the FRP Flash option bit prevents reading of
the user code using the On-Chip Debugger. For more details, see
page 119 and
Flash Code Protection Against Erasure
The Z8 Encore! F083A Series provides several levels of protection against accidental
program and erasure of the Flash memory contents. This protection is provided by a
combination 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 FHSWP and FWP Flash option bits combine to provide three levels of Flash
program memory protection as listed in
Flash Option Bits
Flash programming and erasure are not supported for system clock frequencies below
10 kHz or above 20 MHz. The Flash frequency high and low byte registers must be
loaded with the correct value to ensure operation of the Z8 Encore! F083A Series
devices.
On-Chip Debugger
=
on page 119.
System Clock Frequency (Hz)
--------------------------------------------------------------------------- -
on page 133.
1000
Table 69
on page 111. For more details, see
Z8 Encore!
Product Specification
Flash Option Bits
®
F083A Series
Flash Memory
on
110