Z8F0830HH020SG Datasheet, PDF (132/257 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore!^® F0830 Series
Product Specification
114
Flash Operation Timing Using the Flash Frequency Registers
Before performing either a Program or Erase operation on Flash memory, the user 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 rang-
ing 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 fre-
quency value must contain the system clock frequency (in kHz). This value is calculated
using the following equation:
FFREQ[15:0] = ^{S----y---s--t--e---m------C----l-o---c---k-----F---r--e---q---u---e--n---c---y-----(--H----z---)}
1000
Caution: 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! F0830 Series devices.
Flash Code Protection Against External Access
The user code contained within Flash memory can be 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 information, see the Flash Option
Bits chapter on page 124 and the On-Chip Debugger chapter on page 139.
Flash Code Protection Against Accidental Program and
Erasure
The Z8 Encore! F0830 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 FHSWP and FWP Flash option bits combine to provide three levels of Flash program
memory protection, as listed in Table 71. See the Flash Option Bits chapter on page 124
for more information.
PS025113-1212
Operation