Z8F082ASH020SC datasheet(157/244 Pages) ZILOG

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PS024705-0405

P R E L I M I N A R Y

Flash Option Bits

Z8 Encore! XP® F08xA Series

Product Specification

139

Option Bit Types

User Option Bits

The user option bits are contained in the first two bytes of program memory. User access

to these bits has been provided because these locations contain application-specific device

configurations. The information contained here is lost when page 0 of the program mem-

ory 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 may 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 work-

ing value of the target trim data byte.

The trim address range is from information address 20-3F only. The remainder of the

information page is not accessible through the trim bit address and data registers.

Calibration Option Bits

The calibration option bits are also contained in the information page. These bits are fac-

tory programmed values intended for use in software correcting the device’s analog per-

formance. To read these values, the user code must employ the LDC instruction to access

the information of the address space, as defined in “Flash Information Area” on page 13.

The following code example shows how to read the calibration data from the flash infor-

mation area.

; get value at info address 60 (FE60h)

ldx FPS, #%80 ; enable access to flash info page

ld R0, #%FE

ld R1, #%60

ldc R2, @RR0 ; R2 now contains the calibration value

Note:

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