Z8F0830HH020SG Datasheet, PDF (143/257 Pages) Zilog, Inc. – High-Performance 8-Bit Microcontrollers

Z8 Encore!^® F0830 Series
Product Specification
125
Option Bit Types
This section describes the two types of Flash option bits offered in the F0830 Series.
User Option Bits
The user option bits are contained in the first two bytes of program memory. User access
to these bits is provided because these locations contain application specific device config-
urations. The information contained here is lost when page 0 of program memory is
erased.
Trim Option Bits
The trim option bits are contained in the information page of the Flash memory. These bits
are factory programmed values required to optimize the operation of onboard analog cir-
cuitry and cannot be permanently altered by the user. Program memory can be erased
without endangering these values. It is possible to alter working values of these bits by
accessing the trim bit address and data registers, but these working values are lost after a
power loss.
There are 32 bytes of trim data. To modify one of these values, the user code must first
write a value between 00H and 1FH into the Trim Bit Address Register. The next write to
the Trim Bit Data Register changes the working value of the target trim data byte.
Reading the trim data requires the user code to write a value between 00H and 1FH into the
Trim Bit Address Register. The next read from the Trim Bit Data Register returns the
working value of the target trim data byte.
Note: The trim address range is from information address 20–3F only. The remaining informa-
tion page is not accessible via the Trim Bit Address and Data registers.
During reset, the first 43 system clock cycles perform 43 Flash accesses. The six bits of
the counter provide the lower six bits of the Flash memory address. All other address bits
are set to 0. The option bit registers use the 6-bit address from the counter as an address
and latch the data from the Flash on the positive edge of the IPO clock, allowing for a
maximum of 344-bits (43 bytes) of option information to be read from Flash.
Because option information is stored in both the first two bytes of program memory and in
the information area of Flash memory, the data must be placed in specific locations to be
read correctly. In this case, the first two bytes at addresses 0 and 1 in program memory are
read out and the remainder of the bytes are read out of the Flash information area.
PS025113-1212
Operation