Remote-processing RPC-2350 Manuel d'utilisateur télécharger pdf (Page 29)

CHAPTER 5 DATA MEMORY

5-3

A CAM BASIC program number and Flash segment

when using SAVE are related by the following formula:

SAVE segment = program + 8

Keep track of where you are writing to. Most programs

will only use program area 0. Addresses above &9000

are always available in any program area. However, if

you have many program s, you will have to keep track of

where you are saving data to make sure a program does

not get clobbered.

LOAD is used to transfer data from Flash to RAM. An

example of data include arrays used in CAMBASIC.

This is explained further below.

Saving and Initializing Arrays and data

Sometimes it is convenient to save an array of

information to battery backed RAM and/or F lash for

retrieval later. T his is a handy way of storing “ recipes”

or tables of information for each job, customer, or

process.

Arrays are initialized and filled by the basic program.

Then, they are saved to either RAM or Flash EPROM.

The num ber and size of arr ays that can be saved is

limited only by available memory. The saved arrays can

be retrieved at any time.

How arrays are saved and retrieved depends upon what

kind of memory you are saving to and loading from. If

arrays are saved to Flash , use SAVE . U se LOA D to

both save to and retrieve from RAM.

An exam ple of saving ar rays to RAM is shown in

ARRAY1.BAS program, on the application disk. Saving

arrays to Flash is shown in ARRAY2.BAS.

FLASH .BA S shows strings, bytes, and wor d saves to

Flash. ARRAY3.BAS is similar to ARRAY1.BAS

except it uses LOAD to transfer arrays. This makes

transfers faster.

Mapping your stored data

A frequent question is “Where do I store my data?” and

“How much do I have?” You have two places to store

data: RAM or Flash. How much you have depends upon

several factors:

Expected program size

How much RAM and/or Flash memory is free

Will you need a second program?

Amount of data to store

Type of data to store

How simple do you want to keep the program

How secure does the data have to be (where to store

data - Flash or RAM)

How often is information updated

Every application has a different set of priorities. Some

programs are large, but only a few variables are stored.

Others, some data is critical and some are not. Start off

by determining what your storage requirements are (that

is, floating point numbers, integers, strings, screen

graphics.. .).

64K to 448K bytes of RAM are available, depending on

how U2 is populated. E ach data element type r equires a

different number of bytes. Use the following table to

determine your storage r equireme nts:

Type Bytes of

storage

BASIC Commands

Byte 1 POKE & PEEK

Word 2 DPOKE & DPEEK

Float 4 FPOKE & FPEEK

String 1+ maximum

string length

POKE$ & PEEK$

Graphic 32 - 9600

bytes

DISPLAY LOAD

Program

Size

1-32K SYS(0)

The mathematics for keeping track of addresses can get

quite messy. It all depends upon your data structure. If

you are trying em ulate a struc ture in C or vector s in

JAVA, you will have some math to access the right data.

The demonstration program LOGGE R.BAS logs at over

2000 points using the structure below.

Suppose you are logging a process and need to store the

following types of information periodically:

Name Type Bytes

Date String 9

Time String 9

Tempe rature Float 4

Tick time Float 4

Level word 2

First add up the total num ber of bytes needed. For this

1 2 ... 24 25 26 27 28 29 30 31 32 33 34 ... 82 83

Commentaires sur ces manuels

Pas de commentaire

Remote-processing RPC-2350 Manuel d'utilisateur Page 29

Commentaires sur ces manuels

Produits connexes et manuels pour Ordinateurs Remote-processing RPC-2350