Using EEPROM to store variables...

[Tom Gonser]

Ralph:

Thanks for the demo code, here is what the result was - pasted from the Hyperterminal window. (I added "writing:" to the string so I could see that it was becuse it was not writing anything that showed up on the screen.)
---------------------------------------------------------------------

** MCU started

** EEPROM written

writing:
writing:
writing:
writing:
writing:
writing:
writing:
writing:
writing:
writing:

--------------------------------------------------------------------------

Here is the code I used:

'--------------------------------------------------------------------------------

'Tom,

'on my DataLoggers I have 16F876 or 18F252 and 2x 24LC512.
'The following code is tested.
'could you give it a try and let us know what the result was?


' -----[ Fuses ]------------------------------------------------
@ __CONFIG _CONFIG1H, _OSC_INTIO67_1H
@ __CONFIG _CONFIG2H, _WDT_ON_2H & _WDTPS_128_2H
@ __CONFIG _CONFIG3H, _PBADEN_OFF_3H & _MCLRE_OFF_3H
@ __CONFIG _CONFIG4L, _LVP_OFF_4L & 0bfh ;_XINST_OFF_4L
'
' -----[ Includes/Defines ]---------------------------------------------------------
include "modedefs.bas" 'include serout defines

OSCCON=%01111000
DEFINE OSC 8
While OSCCON.2=0:Wend


SCL var PortC.5 ' I2C Clock
SDA var PortC.4 ' I2C Data
ROM0 CON $A0 ' EEPROM 0 Address
ADDR VAR word ' ROM Location
MonPort var PortC.6 ' Monitor Port
Mode con 16572 ' 4800 Baud 8N1 for Monitor Port

Test var byte[21] ' Test Array
I2Cdelay con 10 ' Delay after I2Cwrite

Temp var byte

CLEAR

SEROUT2 MonPort,Mode,[13,10,"** MCU started",13,10,13,10]

ADDR=100

I2CREAD SDA,SCL,ROM0,ADDR,[Temp]

IF Temp="*" THEN GOTO SkipWrite

I2CWRITE SDA,SCL,ROM0,ADDR,_
[$2A,$20,$54,$65,$73,$74,$20,$45,$45,$50,$52,$4F,_
$4D,$20,$2D,$2D,$3E,$20,$4F,$4B,$21]

PAUSE I2Cdelay

SEROUT2 MonPort,Mode,["** EEPROM written",13,10,13,10]

GOTO Loop

SkipWrite:

SEROUT2 MonPort,Mode,["** EEPROM write skipped",13,10,13,10]

I2CREAD SDA,SCL,ROM0,addr,[str test\21]

Loop:
SEROUT2 MonPort,Mode,["writing: ", STR Test\21,13,10]
PAUSE 1000
GOTO Loop

END

----------------------------------------------------------------


Is this what you expected?

Tom

[Tom Gonser]

I got to wondering why I was getting nothing in the last build. So I trapped for failures to read and write. I did see that it was just not getting there, so tweaked the port assignments, etc. Here is what I get now:

** MCU started

** EEPROM write skipped

Reading:* Test EEPROM --> OK!
Reading:* Test EEPROM --> OK!
Reading:* Test EEPROM --> OK!
Reading:* Test EEPROM --> OK!
Reading:* Test EEPROM --> OK!

(I added "reading" to it)

The program is as follows:

------------------------------------------------------------------


'--------------------------------------------------------------------------------

'Tom,

'on my DataLoggers I have 16F876 or 18F252 and 2x 24LC512.
'The following code is tested.
'could you give it a try and let us know what the result was?


' -----[ Fuses ]------------------------------------------------
@ __CONFIG _CONFIG1H, _OSC_INTIO67_1H
@ __CONFIG _CONFIG2H, _WDT_ON_2H & _WDTPS_128_2H
@ __CONFIG _CONFIG3H, _PBADEN_OFF_3H & _MCLRE_OFF_3H
@ __CONFIG _CONFIG4L, _LVP_OFF_4L & 0bfh ;_XINST_OFF_4L
'
' -----[ Includes/Defines ]---------------------------------------------------------
include "modedefs.bas" 'include serout defines

OSCCON=%01111000
DEFINE OSC 8
While OSCCON.2=0:Wend

SCL var PortC.3 ' I2C Clock
SDA var PortC.4 ' I2C Data
ROM0 con %10100000 ' address of chip1
ADDR VAR word ' ROM Location
MonPort var PortC.6 ' Monitor Port
Mode con 16572 ' 4800 Baud 8N1 for Monitor Port
Test var byte[21] ' Test Array
I2Cdelay con 10 ' Delay after I2Cwrite

Temp var byte

CLEAR

SEROUT2 MonPort,Mode,[13,10,"** MCU started",13,10,13,10]

ADDR=100

I2CREAD SDA,SCL,ROM0,ADDR,[Temp]

IF Temp="*" THEN GOTO SkipWrite

I2CWRITE SDA,SCL,ROM0,ADDR,_
[$2A,$20,$54,$65,$73,$74,$20,$45,$45,$50,$52,$4F,_
$4D,$20,$2D,$2D,$3E,$20,$4F,$4B,$21],failw

PAUSE I2Cdelay

SEROUT2 MonPort,Mode,["** EEPROM written",13,10,13,10]

GOTO Loop

SkipWrite:

SEROUT2 MonPort,Mode,["** EEPROM write skipped",13,10,13,10]

Loop:
I2CREAD SDA,SCL,ROM0,addr,[str test\21],failr
SEROUT2 MonPort,Mode,["Reading:", STR Test\21,13,10]
PAUSE 1000
GOTO Loop

failr:
serout2 monport, mode,["failure to read",10,13]
return

failw:
serout2 monport, mode,["failure to write",10,13]
return


END

[NavMicroSystems]

So your Hardware is OK.

There must be something wrong with your code.

[Tom Gonser]

Hmm.. I am keeping trying to unravel this -- I have a version of your program, but it won't compile.. Can you tell my why I have a 'bad expression'??? It says the I2Cwrite, I2Cread commands are wrong.. I cannot for the life of me make them compile - defining X as a word, byte, whatever..

TG

'on my DataLoggers I have 16F876 or 18F252 and 2x 24LC512.
'The following code is tested.
'could you give it a try and let us know what the result was?
' -----[ Fuses ]------------------------------------------------
@ __CONFIG _CONFIG1H, _OSC_INTIO67_1H
@ __CONFIG _CONFIG2H, _WDT_ON_2H & _WDTPS_128_2H
@ __CONFIG _CONFIG3H, _PBADEN_OFF_3H & _MCLRE_OFF_3H
@ __CONFIG _CONFIG4L, _LVP_OFF_4L & 0bfh ;_XINST_OFF_4L
'
' -----[ Includes/Defines ]---------------------------------------------------------
include "modedefs.bas" 'include serout defines

OSCCON=%01111000
DEFINE OSC 8
While OSCCON.2=0:Wend

SCL var PortC.3 ' I2C Clock
SDA var PortC.4 ' I2C Data
ROM0 con %10100000 ' address of chip1
ADDR VAR word ' ROM Location
portout var PortC.6
portin var PortC.7
Mode con 16572 ' 4800 Baud 8N1 for Monitor Port
Test var byte[21] ' Test Array
I2Cdelay con 10 ' Delay after I2Cwrite

Temp var byte
X var byte
dta var byte

CLEAR

loop:
SEROUT2 portout,Mode,[13,10,"** MCU started",13,10,13,10]
serout2 portout, mode, ["enter 1 to write data, 2 to read it"]
serin2 portin, mode, [DEC temp]

select case temp
case 1
for X = 0 to 256
I2Cwrite SDA, SCL,ROMO,X,[X],failw
pause 10
next x
case 2
for x = 0 to 256
I2Cread SDA,SCL,ROMO,X,[X],failr
Serout2 portout, mode, ["Address: ",#addr," Data:",#dta]
pause 100
next x
end select

goto loop:

failr:
serout2 portout, mode,["failure to read",10,13]
return

failw:
serout2 portout, mode,["failure to write",10,13]
return


END

[Tom Gonser]

... ahem nevermind.. I was using ROMO instead of ROM0... shortened it to ROM so I could not make that mistake, and it works.

NOW I have a program that tests memory.. and the use of WORD or BYTE.. This will read or write to memory. VERY odd behavour tho, leading me to think I am missing some key understanding:

I write 0-640 to memory 0-640.. When I read it back I get REALLY odd stuff... NOT 0-640:

'on my DataLoggers I have 16F876 or 18F252 and 2x 24LC512.
'The following code is tested.
'could you give it a try and let us know what the result was?
' -----[ Fuses ]------------------------------------------------
@ __CONFIG _CONFIG1H, _OSC_INTIO67_1H
@ __CONFIG _CONFIG2H, _WDT_ON_2H & _WDTPS_128_2H
@ __CONFIG _CONFIG3H, _PBADEN_OFF_3H & _MCLRE_OFF_3H
@ __CONFIG _CONFIG4L, _LVP_OFF_4L & 0bfh ;_XINST_OFF_4L
'
' -----[ Includes/Defines ]---------------------------------------------------------
include "modedefs.bas" 'include serout defines

OSCCON=%01111000
DEFINE OSC 8
While OSCCON.2=0:Wend

SCL var PortC.3 ' I2C Clock
SDA var PortC.4 ' I2C Data
ROM con %10100000 ' address of chip1
ADDR VAR word ' ROM Location
portout var PortC.6
portin var PortC.7
Mode con 16572 ' 4800 Baud 8N1 for Monitor Port
Test var byte[21] ' Test Array
I2Cdelay con 10 ' Delay after I2Cwrite

Temp var byte
X var word
dta var word

CLEAR

Addr=100
loop:
SEROUT2 portout,Mode,[13,10,"** MCU started",13,10,13,10]
serout2 portout, mode, ["enter 1 to write data, 2 to read it"]
serin2 portin, mode, [DEC1 temp]

select case temp
case 1
for X = 0 to 640
I2Cwrite SDA, SCL,ROM,X,[X],failw
Serout2 portout, mode, ["Write Address: ",#x," Data:",#X,10,13]
pause 10
next x
case 2
for x = 0 to 640
I2Cread SDA,SCL,ROM,X,[dta.byte0],failr
I2Cread SDA,SCL,ROM,X+1,[dta.byte1],failr
Serout2 portout, mode, ["Address: ",#x," Data:",#dta,10,13]
pause 10
next x
case else
goto loop
end select

goto loop:

failr:
serout2 portout, mode,["failure to read",10,13]
return

failw:
serout2 portout, mode,["failure to write",10,13]
return


END

[Tom Gonser]

OK, I am drained.. here is the last program. I have been experimenting with BYTE and WORD and notice they make the memory behaviour REALLY different.. In any event, I have noticed:

1. I can WRITE from 0-640 to memory
2. When I READ this back, it is all '0's..
3. When I ERASE it ($FFFF), and read it back it is all 65355..

I THINK somehow I am writing PAGES using the [x] brackets..(???) I want to write to SPECFIC memory locations.. but can't figure out the syntax for that. maybe that is why the data is all messed up? So I tried putting it in increments of 128.. still reading back '0'..

Anyway - here is the sample program that lets you write, read and erase from an external 24LC512... and get back zeros..

TG

------------------------

'on my DataLoggers I have 16F876 or 18F252 and 2x 24LC512.
'The following code is tested.
'could you give it a try and let us know what the result was?
' -----[ Fuses ]------------------------------------------------
@ __CONFIG _CONFIG1H, _OSC_INTIO67_1H
@ __CONFIG _CONFIG2H, _WDT_ON_2H & _WDTPS_128_2H
@ __CONFIG _CONFIG3H, _PBADEN_OFF_3H & _MCLRE_OFF_3H
@ __CONFIG _CONFIG4L, _LVP_OFF_4L & 0bfh ;_XINST_OFF_4L
'
' -----[ Includes/Defines ]---------------------------------------------------------
include "modedefs.bas" 'include serout defines

OSCCON=%01111000
DEFINE OSC 8
While OSCCON.2=0:Wend

SCL var PortC.3 ' I2C Clock
SDA var PortC.4 ' I2C Data
ROM con %10100000 ' address of chip1
ADDR VAR word ' ROM Location
portout var PortC.6
portin var PortC.7
Mode con 16468 ' 4800 Baud 8N1 for Monitor Port
Test var byte[21] ' Test Array
I2Cdelay con 10 ' Delay after I2Cwrite

Temp var byte
X var word
dta var word

CLEAR

Addr=100
loop:
SEROUT2 portout,Mode,[13,10,"** MCU started",13,10,13,10]
serout2 portout, mode, ["enter 1 to write data, 2 to read it, 3 to erase"]
serin2 portin, mode, [DEC1 temp]

select case temp
case 1
for X = 0 to 640 step 128
I2Cwrite SDA, SCL,ROM,X,[X],failw
Serout2 portout, mode, ["Read Address: ",#X," Data:",#X,10,13]
pause 10
next x
case 2
for x = 0 to 640 step 128
I2Cread SDA,SCL,ROM,X,dta,failr
Serout2 portout, mode, ["Read Address: ",#X," Data:",#dta,10,13]
next x
Case 3
for x = 0 to 640 step 128
I2Cwrite SDA,SCL,ROM,X,[$FFFF],failw
Serout2 portout, mode,["Erasing Address: ",#X," Data:",$FFFF,10,13]
pause 10
next x
case else
goto loop
end select

goto loop:

failr:
serout2 portout, mode,["failure to read",10,13]
return

failw:
serout2 portout, mode,["failure to write",10,13]
return

END

[NavMicroSystems]

Tom,

your code works as designed.

In the FOR...NEXT loop to write the eeprom you are counting from 0 to 640.
X is a WORD size variable and being used as EEPROM address as well as value to be written.
This means you are writing a WORD (two BYTES) to the EEPROM.
This requires two BYTE locations in your EEPROM.
By incrementing the address counter by 1 the LowByte of the last WORD written will always be overwritten with the HighByte oft the current WORD.

here is a working example:

for X = 0 to 640 
I2Cwrite SDA, SCL,ROM,X*2,[x]
pause 10
Serout2 portout, mode, ["Write Address: ",#x*2," Data:",#x,10,13]
dta=dta+1
next x

for x = 0 to 640 
I2Cread SDA,SCL,ROM,X*2,[dta]
Serout2 portout, mode, ["Address: ",#x*2," Data:",#dta,10,13]
pause 100
next x