WRITE TO Eeprom

[crhomberg]

Hi all,

Has anyone any idea why the write command does not want to work inside a hardware interrupt routine. Is it maybe too fast or is it maybe that with MPASM things are different.
My program uses Darrel's instant interrupts and when in the interrupt it gets a new piece of data and must write it to EEPROM. Before I started with the interrupts and used polling and PM all worked fine, now no data change in eeprom.

This is the Interrupt routine:
'==================== DATA RECEIVE ROUTINE ==============================

GETDATA:
'serout2 test,baud,["int",10,13]

IF RCIF=1 THEN 'DATA IS READY TO BE COLLECTED
'REMOVE BYTE FROM RCIF REGISTER

VALUE=RCREG
IF VALUE = $A0 THEN 'CHECK TO SEE IF THE BYTE IS THE START BYTE
BYTECOUNTER=0
ENDIF
'Serout2 test,BAUD,["int",10,13] 'TO SHOW OVERFLOW

IF BYTECOUNTER < 8 THEN
BUFFER[BYTECOUNTER] = VALUE 'ADD BYTE TO PACKET
BYTECOUNTER=BYTECOUNTER+1 'INCREMENT COUNTER
ENDIF

'************ CHECK IF OVERRUN HAS OCCURRED *******************************

IF OERR=1 THEN
Serout2 test,BAUD,["OERR",10,13] 'TO SHOW OVERFLOW
PAUSE 1000
CREN=0 'STOP CONTINUOUS RECEIVE
CREN=1 'RESTART CONTINUOS RECIEVE & CLEAR THE OVERRUN FLAG
BYTECOUNTER=0 'RESET COUNTER AS PART OF PACKET HAS BEEN LOST SO START AGAIN
BUFFER=0
GOTO GETDATA
ENDIF

'************** PACKET MUST START WITH $A0 AND HAVE $AF AS IT'S 7TH BYTE. ******

IF BYTECOUNTER=7 AND BUFFER[0]=$A0 AND BUFFER[6]=$AF THEN
GOT=1 'INDICATE THAT THIS IS A NEW PACKET

' ****************** PRESET CONTROL **********************************


IF ID = (BUFFER[1]+1) THEN 'CHECK IF ID IS FOR THIS INSERTADOR &
'PELCO VALUE STARTS AT 0 SO NEED TO ADD 1

IF BUFFER[3]=$07 THEN

preset=buffer[5]

IF PRESET=0 THEN
PRESET=1 'Ensure that preset 0 is never used as inputs start at 1
ENDIF

IF PRESET=76 THEN
DATA_OFF=1
GOTO JUMP
ENDIF

if preset < 24 then
DATA_OFF=0

write 0,preset '******* HERE IT SHOULD WRITE ******
else
read 0,preset 'If preset entered is above 24 read last saved preset
endif

JUMP:

endif

endif

ELSE
GOTO GETDATA 'IF PACKET NOT COMPLETE GO BACK FOR NEXT BYTE
ENDIF


ENDIF

@ INT_RETURN

[skimask]

I'm fairly sure that you have to shut off ALL interrupts while trying to write to eeprom or flash, not just DISABLE interrupts. You actually have to disable the global interrupt enable flag, then reenable it when the write is done.

[crhomberg]

I'm fairly sure that you have to shut off ALL interrupts while trying to write to eeprom or flash, not just DISABLE interrupts. You actually have to disable the global interrupt enable flag, then reenable it when the write is done.

I Tried moving the WRITE statement to the main program like this but it still does'nt write:

INTCON = %00000000 'DISABLE GLOBAL & PERIFERAL INTERRUPTS
WRITE 0, PRESET
PAUSE 10
INTCON = %11000000

Regards

Chris

[mister_e]

mm, seems the ISR is too long anyways... can you post your whole code and tell which PIC you're using?

Not sure if it's a good idea to write to a EEPROM in a USART ISR.

[crhomberg]

[I am using a 16F877A at 20MHz

I use timer1 to check the dip switch settings for the device's address and the UASRT one for data in.

Sorry for using attachment, my code was too long for the forum page

[skimask]

[I am using a 16F877A at 20MHz

I use timer1 to check the dip switch settings for the device's address and the UASRT one for data in.

Sorry for using attachment, my code was too long for the forum page

Isolate the problem...
Start with a program without any serial input or output, no nothing, just a couple of LEDs and maybe a button or two.
Write and Read the EEPROM and make the LEDs show you if the write/read works correctly or not, use the buttons to increment the addresses and data to be written.
Something tells me that something else in your program isn't working right in the first place, making you think that the EEPROM isn't being written correctly...
Maybe PBP work for you...not the other way around...

[ria_river]

Hi everyone!

I can read and write now using the pic16f84a but I can't do that using pic16f877a.
Is there any lines I have to add inorder to allow reading and writing the eeprom?
I've read the 16f877a datasheet. It is stated there that I have to disable all interrupts before writing. I've tried that but still won't work.

A working simple code for reading and writing the internal eeprom of pic16f877a is all I need.

Please help me...
Thank you in advance.

[kindred22]

trisb=0
portb=0
aa var byte
bb var byte

eeprom 2,[0]
aa=4

write 2, aa
read 2, bb

if bb==4 then
portb.0=1
endif

I tried 16f84a it function, the LED at portb.0 lights up..
but in 16f877a, the LED did not light...
what happen to this situation?
is there a need to disable interrupts?
with that simple program....

HELP US PLS....
thnx....

[skimask]

1 - which version of PBP are you using?
2 - what clock speed are you trying to run with?
3 - which programmer are you using?

[ria_river]

from kindred:
picbasic pro compiler version 2.3
4MHz
kit128

[skimask]

from kindred:
picbasic pro compiler version 2.3
4MHz
kit128

PBP 2.3? Upgrade to 2.50a... $20 says you can't do it!
877A support isn't in 2.3 according to melabs support page.