Remote-processing RPC-30 Bedienungsanleitung PDF herunterladen (Seite 36)

SERIAL EEPROM CHAPTER 13

Page 34 RPC-30

DESCRIPTION

The serial EEPROM is a 128 byte, non-volatile device

that stores your programs parameters. Strings, integers,

and floating point numbers can be saved to EEPROM.

Information such as calibration constants, recipes, RS-

485 address, or other "soft" inform ation that may change

over time should be stored in the serial EEPROM.

The LOAD # and SAVE # commands are used to get

and store data to and from the EE PROM . The syntax is:

SAVE #address

LOAD #address

Where address is the location in RAM. address is in the

range of &8000 to &FFFF . Take ca re to make sure you

are not POKEing into program or reserved memory

addresses. Use the SYS(1) and SYS(2) functions to the

addresses for free space. LOA D and SA VE effectively

require 128 bytes of free RAM . The L OAD # com mand

reads 128 bytes from the serial EEPROM and transfers

this information starting at the address specified.

An EEPROM is more secure than battery backed RAM

because it is more difficult to write to it. Several

microprocessor instructions must take place before a

byte is changed. RAM , on the other hand, requir es only

a momentary pulse to modify its memor y.

Each byte can be written to 10,000 times and read from

any number of times. The EEPROM could be updated

once a day for over 27 year s before this limit is

exceeded.

Do not constantly store information to the EEPROM.

That is, do not continuously write to it once a second as

part of your program . This is one electronic part you

can "wear out".

PROGRAM EXAMPLE

The following program example saves and retrieves a

string and a number to the serial EEPROM.

100 'Save to EEPROM

110 'Put string of known length to RAM

120 A$ = ">03"

130 C = 14.35

140 POKE$ &E000,A$

150 'Put a number to RAM

160 FPOKE &E020,C

170 'Save to EEPROM

180 SAVE #&E000

200 'Load from EEPROM

210 LOAD #&E000

220 'Now put info in variables

230 B$ = PEEK$(&E000)

240 D = FPEEK(&E000)

When saving strings, the amou nt of mem ory r equired is

1 + the string length. Floating point numbers require 6

bytes, integers r equire only 1 byte. You may find it

desirable to make a "memory" map of the data types you

wish to save. You can " stack" different kinds of data

next to each other (strings, integers, floating point

numbers) so long as you know where you are saving and

retrieving them.

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