Internal eeprom - erase block

[ruijc]

Hi guys,

will start making some experiments with saving data to eeprom and dumping the data to lcd or PC via rs232.

First i will try with the internal eeprom to see how that works and after with an external eeprom.

I've been reading the pbp manual and will use the write and read commands.

My first question is :

My code will need to sart with clearing the eeprom before saving new data ( 1st erase old data then save new data ).

Is there a simple way to erase ( by code ) all internal eeprom memory at the beggining of the program ?

Thanks
.

[atwoz]

So you want to erase the eeprom every time the pic is started?

I'm rather new to pics and PB, but I'll give you my opinion .

Maybe you can add something like:

w0 var word
for w0 = 0 to 255 'It depends on how many slots you want to erase, I'm erasing 256
write w0, 0 'We write a zero to the eeprom at the desired location, like erasing it
next w0 ' we continue with the next w0

hope this helps.

By the way, there's the Data command, with it you can preset the eeprom to whatever you want at the time of the programing. You add Data @0,2,6, 3, 50, etc at the beginning of your program and when your program your pic (not every time you power it up) the eeprom recieves the values you specified, in this case:

eeprom 0 = 0
eeprom 1 = 2
eeprom 2 = 6
eeprom 3 = 3
eeprom 4 = 50

bye

Art

[atwoz]

Look at what I found. Darrel creates some really awesome extensions all the time, maybe this one will help you with what you are doing.

http://www.picbasic.co.uk/forum/showthread.php?t=2444

[sayzer]

Check this one.
Modify as needed.

ReadMem VAR BYTE
Value   VAR BYTE

Begin:

    FOR ReadMem = 0 TO 128  'Scan eeprom
        READ ReadMem, Value 
        IF Value <> $FF THEN Start
    NEXT ReadMem

Start:

' your "value" variable gets a value here.
'..
'....

' when you want to save something into eeprom, goto "save".

GOTO Start


Save:
            IF ReadMem = 128 THEN    ' last eeprom location. 
               WRITE 0, Value        ' thus, start from the beginning
               WRITE 128, $FF        ' assign $FF to last written eeprom location.
            ELSE
               WRITE ReadMem + 1, value 'save your value into eeprom after the current eeprom address.
               WRITE ReadMem, $FF       'assign $FF to the current eeprom location.
            ENDIF                       'new eeprom location will be incremented,
            GOTO Begin               '...with the next eeprom scan.

[ruijc]

atwoz,

thanks for the help...also...very interesting link

sayzer,

also thanks for the help.

Nice code

If i understand it will search the eeprom for a good value, send it to "start" to process it.
Then when saving, saves the new value to the eeprom and deletes the previous address value.

This can be very handy

Although what i will be using is more like this:

1st : erase all eeprom if button #1 pressed
2nd : send all data stored in eeprom via rs232 if button #2 pressed
3rd : start collecting data and saving it to eeprom if button #3 pressed
4th : stop collecting data and go back to starting loop if button #4 pressed


Since the data being colected and saved into the eeprom will be unique ( meaning that everytime the pic restarts and will if it will colect data it cannot be mixed with old data ) the entire eeprom will have to be deleted and ready to receive o toon of fresh continuous data.

.

[sayzer]

I see.

But, if you are erasing eeprom very frequently in your application, I do not now what "very frequently means ??", then your eeprom will be dead "very soon".

Then, very soon, your customers will be calling you "very frequently".