Zilog Z8F0130 - Manual (Page 129)

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Zilog Developer Studio II – Z8 Encore!
User Manual
105
The Z8 Encore! XP 4K and 16K devices contain a Nonvolatile Data Storage (NVDS)
element with a size of up to 128 bytes. This memory features an endurance of 100,000
write cycles. For more information about NVDS, see the Nonvolatile Data Storage
chapter of the
Z8 Encore! XP F082A Series Product Specification (PS0228) .
•
PRAM (Program RAM)
The Z8 Encore! XP F1680 Series devices feature an area of Program RAM that can be
used for storing some code in RAM. This area can be used to help keep device operat-
ing power low by, for example, storing interrupt service routines here that would acti-
vate the code in Flash memory when some external event has occurred. PRAM, when
available, is an optional feature. If you want to use this memory as Program RAM,
select the
Use PRAM checkbox and then adjust the address range in the PRAM field.
PRAM begins at data address E000 and can have a maximum size of 512 or 1024
bytes, depending on your device. If you deselect the Use PRAM checkbox, this mem-
ory is not available as PRAM but instead can be mapped as additional EData memory
(see the EData memory discussion).
It is your responsibility to set the Flash option bytes to reflect whether you are using this
memory as PRAM or as EData. This task must be performed inside your program so that
the part will still get configured correctly even when the hex file is downloaded outside of
ZDS II. The PRAM_M bit is bit 1 of Flash option byte 1 (see the product specification).
Writing to the Flash option bytes must be done only once and takes effect when your hex
file is downloaded to Flash. Therefore, if you wanted to set all of the other bits of Flash
option byte 1 to their default value of 1, but set the PRAM_M bit to 0 to indicate that you
will not be using this memory as Program RAM, use the following code in your program:
#include

FLASH_OPTION1 = 0xFD;
This example is only for illustration, of course; it is your responsibility to make sure that
all bits of the Flash option bytes are set as you need them for your application.
Data addresses F00 through FFF are reserved for special function registers (SFRs).
Address ranges are set in the Address Spaces fields. The syntax of a memory range is:
<low address> – <high address> [,<low address> – <high
address>] ...
In the above syntax example, <low address> is the hexadecimal lower boundary of a range
and <high address> is the hexadecimal higher boundary of the range. The following are
legal memory ranges:
Note:
Note: