Need help with write function

[Christopher4187]

Yes, I have RTFD and still don't quite understand how to do it. In the PBP manual, it says that you can do something like:

Write 0, Brakes
Write 1, Lights

Then, you can read them by doing this:

Read 0, Brakes
Read 1, Lights

But according to the 16F688 datasheet, it says that the memory register is different and has to be accesed through the EECON1, EECON2........and I am not sure how to set up the code to write.

Can someone help me with the write function please?

Thanks,

Chris

[Melanie]

DATA, READ and WRITE are the correct commands for the internal EEPROM in the 16F688 chip. Make sure your version of PICBasic supports this chip, and you have any patches installed. Check on MeLabs website.

[paul borgmeier]

Just to add ... PBP takes care of all the EECON1 and EECON2 stuff so you do not have to - you just need DATA, READ, and WRITE.

See example code on melabs website
http://www.melabs.com/resources/samples/pbp/ee.bas

Paul Borgmeier
Salt Lake City, Utah
USA

[Christopher4187]

Thanks for the help. I am still a bit unclear, so I want to know if I can do something like this (I would do it myself with the PIC but I won't be able to until tomorrow):

Beep var byte
flash var byte


Gosub EEPROM


Start:

if portb.4=1 then
beep=beep+1
gosub EEPROM

if beep=1 then
high portb.0
endif

if portb.3=1 then
flash=flash+1
gosub EEPROM

if flash=2 then
high portb.1
endif

goto start


EEPROM:

write 0, beep
write 1, flash
return

I know this isn't a very complex code but the reason I need to write to the EEPROM is because I need to change functions on an alarm system after the PIC is already programmed. Some questions.... if for example I just say "flash var byte," does the PIC automatically recognize flash as a zero? Lets say the PIC has been running for a while and flash=7. Now, I power off the PIC and it holds the 7 in memory. If I goto power up the PIC and I have it go directly to the write command, will it simply just write over flash but still make it 7? Also, do I need the read command or can I just say "If beep=1 then......?"

Thanks,

Chris

[Archilochus]

Hi Chris,
Maybe one of the pros will add some more answers, but for now...

if for example I just say "flash var byte," does the PIC automatically recognize flash as a zero?

PBP does not initialize RAM variables to any value, and on power up the RAM variables will contain an unknown value. You can use the CLEAR command to clear all RAM variables to 0, or just set each variable to 0 manually: flash=0

After any power up, you'll need to READ your saved settings from EEPROM to restore your user selections.

Keep in mind the EEPROM has a limited number of write/erase cycles (check data sheet for details).

Arch

[Christopher4187]

OK, so I understand when you have used the PIC for a while you just simply read the EEPROM and everything is OK. What I don't understand is the very first time you power up the PIC, how do you deal with the memory? I mean, if you go to read it, it's an unknown value.