I2C with External Eeprom

Hi all,

The reason for this post is that i'm trying to get my 24LC512 eeprom to work with my PIC16F88.

I was successful with this eeprom and a PIC12F675, but for some reason with the 16F88 i cant read nor write anything.

I've search the forum for an answer but nothing worked.

I've read the pic16F88 datasheet over and over and i came up with some doubts.

Please try to answer my questions so i can proceed in finding a solution :)

According to the pic 16F88's datasheet ( I2C )Pin RB1 is for SDA and pin RB4 is for SCL.

1st question:
Is it mandatory that i use these ports to communicate with the eeprom ?
( this may be a silly question but for 12F675 i can use almost any pin for them ).

In the datasheet i have found that we need to clear SSPEN bit and program the 2 I2C ports as inputs.

2nd question:
For that to happen i need to mess with the SSPSTAT and SSPCON ?
If yes, can you please show me how can these be set ( since i dont understand the meaning of their bits :( )

thanks

Quote:

Originally Posted by ruijc

Hi all,
The reason for this post is that i'm trying to get my 24LC512 eeprom to work with my PIC16F88.
I was successful with this eeprom and a PIC12F675, but for some reason with the 16F88 i cant read nor write anything.
I've search the forum for an answer but nothing worked.
I've read the pic16F88 datasheet over and over and i came up with some doubts.
Please try to answer my questions so i can proceed in finding a solution :)
According to the pic 16F88's datasheet ( I2C )Pin RB1 is for SDA and pin RB4 is for SCL.
1st question:
Is it mandatory that i use these ports to communicate with the eeprom ?
( this may be a silly question but for 12F675 i can use almost any pin for them ).
In the datasheet i have found that we need to clear SSPEN bit and program the 2 I2C ports as inputs.
2nd question:
For that to happen i need to mess with the SSPSTAT and SSPCON ?
If yes, can you please show me how can these be set ( since i dont understand the meaning of their bits :( )
thanks

You seem to have a bit of a problem with a little bit of everything, but then, that's why you're here...
PBP's I2C commands pretty much take care of everything for you, no extra work needed, with most chips.
First off, do you have pull up resistors on SDA/SCL like the manual shows?
Second...where's the code?

If you are trying to use the hardware i2c, the 16F88 can't do it--it does not have master i2c capability (only SPI). Therefore, the i2c pin selections are irrelevant--you can connect them anywhere you want, and you'll have to define where they are, and use i2c commands.

Hello skimask and thanks for your help :)

Yes...i have the 4k7 pull ups ( also tryed other resistor values with no success.

here is the code :

Code:

***** SSPCON.5 = 0 ; Disable SSP Module TXSTA.5 = 0 ; Disable AUSART Tx RCSTA.7 = 0 ; Disable Serial Port OSCCON = %01111110 'Internal RC w/ I/Os INTCON=0 PIE1 = 0 'PIE2 = 0 PIR1 = 0 'off CMCON= 7 CVRCON= 0 'Vref Off CCP1CON= 0 T1CON= 0 'T2CON = %00000100 '***************************************************************************** 'DEFINEs '***************************************************************************** @ DEVICE INTRC_OSC @ DEVICE MCLR_OFF @ DEVICE PROTECT_OFF DEFINE osc 4 @ DEVICE CPD_OFF @ DEVICE LVP_OFF @ DEVICE BOD_OFF @ DEVICE PWRT_OFF @ DEVICE WDT_OFF '***************************************************************************** 'ADC DEFINE ADC_BITS 10 ' Set number of bits in result ( 8 or 10 bits ) DEFINE ADC_CLOCK 3 ' Set clock source (3=rc) DEFINE ADC_SAMPLEUS 50 ' Set sampling time in uS '***************************************************************************** 'ADC parameters ADCON1 =%10000000 'right justify ANSEL =%00000101 ADCON0 =%11000001 '***************************************************************************** INCLUDE "modedefs.bas" 'settings for serial comm DEFINE debug_reg PORTA DEFINE debug_bit 1 DEFINE debug_baud 9600 DEFINE debug_mode 1 '***************************************************************************** 'I/O's PORTA=0 PORTB=0 TRISA=%00100101 TRISB=%00000011 '***************************************************************************** 'PINS temp var PORTA.0 out var PORTA.1 volt var PORTA.2 a3 var PORTA.3 A4 var PORTA.4 but1 var PORTA.5 led2 var PORTA.6 led1 var PORTA.7 but2 var PORTB.0 but3 var PORTB.1 SCL var PORTB.2 SDA var PORTB.3 green var PORTB.4 red var PORTB.5 led4 var PORTB.6 led3 var PORTB.7 ***************************************************************************** ' variables va var word va2 var word tempe var word volte var word mem var byte p1a var word p1b var word p2a var word p2b var word p3a var word p3b var word p4a var word p4b var word state var byte st var word ed var word ADDR var word m1 var byte m2 var byte m3 var byte m4 var byte slot var bit w var byte CTW VAR BYTE km var byte ra var word set1 VAR BYTE set2 VAR BYTE rm var byte x var byte CLEAR '***************************************************************************** mem=1 state=1 p1a=$10 p1b=$1070 p2a=$1080 p2b=$2140 p3a=$2160 p3b=$3220 p4a=$3230 p4b=$4290 '***************************************************************************** start: high out debug $0D, $0A PAUSE 50 CTW=$A0 '***************************************************************************** debug "start menu",13,10 startmenu: I2CREAD SDA,SCL,CTW,1,[m1] I2CREAD SDA,SCL,CTW,2,[m2] I2CREAD SDA,SCL,CTW,3,[m3] I2CREAD SDA,SCL,CTW,4,[m4] if (mem=1) and (m1=0) then led1=1 led2=0 led3=0 led4=0 slot=0 endif if (mem=1) and (m1<>0) then pause 300 toggle led1 led2=0 led3=0 led4=0 slot=1 endif if (mem=2) and (m2=0) then led1=0 led2=1 led3=0 led4=0 slot=0 endif if (mem=2) and (m2<>0) then led1=0 pause 300 toggle led2 led3=0 led4=0 slot=1 endif if (mem=3) and (m3=0) then led1=0 led2=0 led3=1 led4=0 slot=0 endif if (mem=3) and (m3<>0) then led1=0 pause 300 led2=0 toggle led3 led4=0 slot=1 endif if (mem=4) and (m4=0) then led1=0 led2=0 led3=0 led4=1 slot=0 endif if (mem=4) and (m4<>0) then led1=0 pause 300 led2=0 led3=0 toggle led4 slot=1 endif if state=1 then green=0 red=1 endif if state=2 then green=1 red=0 endif if state=3 then green=1 red=1 endif if (but1=1) and (state=1) then gosub readmenu endif if (but1=1) and (state=2) then gosub recordmenu endif if (but1=1) and (state=3) then gosub erasemenu endif if but3=1 then gosub memorymenu endif if but2=1 then gosub statemenu endif goto startmenu '***************** recordmenu: debug "Record Menu",13,10 if slot=1 then goto warningmenu endif if mem=1 then st=p1a ed=p1b endif if mem=2 then st=p2a ed=p2b endif if mem=3 then st=p3a ed=p3b endif if mem=4 then st=p4a ed=p4b endif '****************** recordmem: debug "2s pause before start recording",13,10 PAUSE 2000 FOR ADDR= st TO ed for w = 0 to 15 ADCIN temp, va va2=va + (temp>>4) NEXT va = (va2 */ 5000 ) >> 2 va=va/10 toggle red pause 824 debug " Saved value: ", dec va2," - ", dec va," In position ", dec ADDR, 13,10 debug " VA2 = ", dec va2,13,10 I2CWRITE SDA,SCL,CTW,ADDR,[VA.highbyte] pause 10 ADDR=ADDR+1 I2CWRITE SDA,SCL,CTW,ADDR,[VA.lowbyte] pause 10 ADDR=ADDR+1 I2CWRITE SDA,SCL,CTW,mem,[addr] if but1=1 then 'stop recording pause 600 goto startmenu endif toggle led1 toggle led4 NEXT red=1 return '****************** erasemenu: '***************** eraseblock: debug "erasing block",dec mem,13,10 red=0 I2Cread SDA,SCL,CTW,mem,[x] debug "before in position ",dec mem," - ",dec x,13,10 I2CWRITE SDA,SCL,CTW,mem,[0] pause 500 red=1 return '****************** memorymenu: if mem < 4 then mem=mem+1 else mem=1 endif debug DEC mem,13,10 pause 300 return '****************** statemenu: if state < 3 then state=state+1 else state=1 endif debug "state change - ", DEC state,13,10 pause 300 return '****************** end

WP pin pulled high? Low? Floating?
Address pins pulled high? Low? Floating?

WP is connected to ground. Same as all address pins of the eeprom.

Quote:

Originally Posted by ruijc

WP is connected to ground. Same as all address pins of the eeprom.

Then I'd suggest backing up a bit...
Get uncomplicated...
Write some code to just write a few values to the eeprom and read them back to verify what was written...THEN write the code you actually want to use...'cause I see a few flaws in your logic in the code written a few posts back.

Thanks skimask,

Good idea. Will do that tonight and post the results ;)

.

Just finished assembling a small code and still cannot work with the eeprom

this is the code i used :

Code:

'**************************************************************** '**************************************************************** SSPCON.5 = 0 ; Disable SSP Module TXSTA.5 = 0 ; Disable AUSART Tx RCSTA.7 = 0 ; Disable Serial Port OSCCON = %01111110 'Internal RC w/ I/Os INTCON=0 PIE1 = 0 'PIE2 = 0 PIR1 = 0 'off CMCON= 7 'COMPARATOR OFF CVRCON= 0 'Vref Off CCP1CON= 0 T1CON= 0 'T2CON = %00000100 osctune=0 '***************************************************************************** 'DEFINEs '***************************************************************************** @ DEVICE INTRC_OSC @ DEVICE MCLR_OFF @ DEVICE PROTECT_OFF DEFINE osc 8 @ DEVICE CPD_OFF @ DEVICE LVP_OFF @ DEVICE BOD_OFF @ DEVICE PWRT_OFF @ DEVICE WDT_OFF '***************************************************************************** '***************************************************************************** 'ADC parameters ADCON1 =%10000000 'right justify ANSEL =%00000001 'PORTA.0 ANALOG ADCON0 =%11000001 '***************************************************************************** INCLUDE "modedefs.bas" 'settings for serial comm DEFINE debug_reg PORTB DEFINE debug_bit 7 DEFINE debug_baud 9600 DEFINE debug_mode 1 '***************************************************************************** 'I/O's PORTA=0 PORTB=0 TRISA=%00000001 'PORTA.0 AS INPUT TRISB=%00000111 'SDA,SCL AND BUT1 AS INPUTS '***************************************************************************** 'PINS A0 var PORTA.0 a1 var PORTA.1 A2 var PORTA.2 A3 var PORTA.3 A4 var PORTA.4 MCLR var PORTA.5 a6 var PORTA.6 a7 var PORTA.7 SDA var PORTB.0 'I2C DATA PIN SCL var PORTB.1 'I2C CLOCK PIN but1 var PORTB.2 'BUTTON FOR LOOP b3 var PORTB.3 B4 var PORTB.4 B5 var PORTB.5 B6 var PORTB.6 out var PORTB.7 '***************************************************************************** ' variables mem var byte ADDR var word m1 var word m2 var word CTW VAR WORD '***************************************************************************** CTW=$A0 m1=0 m2=0 '***************************************************************************** start: I2CREAD SDA,SCL,CTW,$1,[m1] pause 10 debug " value IN EEPROM address 1 = ",dec m1,13,10 I2CREAD SDA,SCL,CTW,$10,[m2] pause 10 debug " value IN EEPROM address 10 = ",dec m2,13,10 I2CWRITE SDA,SCL,CTW,$1,[5] PAUSE 10 debug " WROTE 5 at address 1 = ",13,10 I2CWRITE SDA,SCL,CTW,$10,[6] PAUSE 10 debug " WROTE 6 at address 10 = ",13,10 loop: if but1=1 then goto start else goto loop endif end

The value returned for both addresses is 257

Just as a note, with the first code ( showned in post #4 ) the returned value was always 8 ( for any address ) and 0 when removing the pullups.

EDIT:
Changed the lines:

I2CWRITE SDA,SCL,CTW,$1,[5]

to

ADDR=$1
I2CWRITE SDA,SCL,CTW,ADDR,[5]

( as seen in Melanie's post about I2C )
http://www.picbasic.co.uk/forum/showthread.php?t=587

but the return value is the same :(

Code:

DEFINE OSC 8 INCLUDE "modedefs.bas" @ DEVICE INTRC_OSC @ DEVICE MCLR_OFF @ DEVICE PROTECT_OFF @ DEVICE CPD_OFF @ DEVICE LVP_OFF @ DEVICE BOD_OFF @ DEVICE PWRT_OFF @ DEVICE WDT_OFF DEFINE DEBUG_REG PORTB DEFINE DEBUG_BIT 7 DEFINE DEBUG_BAUD 9600 DEFINE DEBUG_MODE 1 osccon=$7e:cmcon=7:adcon1=$80:ansel=1:adcon0=$c1:porta=0:portb=0:trisa=1 trisb=7:sda var portb.0:scl var portb.1:addr var word:dat var byte dat2 var byte:ctw con $a0 start: dat=dat+1:addr=addr+1 i2cwrite sda,scl,ctw,addr.highbyte,addr.lowbyte,[dat]:pause 10 debug "Wrote: ",dec addr," with ",dec dat,13,10 i2cread sda,scl,ctw,addr.highbyte,addr.lowbyte,[dat2] debug " Read: ",dec addr," val: ",dec dat2 , 13 , 10 if dat = dat2 then debug "Write/Read Successful at ",dec5 addr," with ",dec3 dat,13,10 else debug "Write/Read Error at ",dec5 addr,"-Wrote:",dec3 dat," - Read:",dec dat2,13,10 endif pause 500:goto start END

OR un-COLONized...

Code:

DEFINE OSC 8 INCLUDE "modedefs.bas" @ DEVICE INTRC_OSC @ DEVICE MCLR_OFF @ DEVICE PROTECT_OFF @ DEVICE CPD_OFF @ DEVICE LVP_OFF @ DEVICE BOD_OFF @ DEVICE PWRT_OFF @ DEVICE WDT_OFF DEFINE DEBUG_REG PORTB DEFINE DEBUG_BIT 7 DEFINE DEBUG_BAUD 9600 DEFINE DEBUG_MODE 1 osccon = $7e cmcon = 7 adcon1 = $80 ansel = 1 adcon0 = $c1 porta = 0 portb = 0 trisa = 1 trisb = 7 sda var portb.0 scl var portb.1 addr var word dat var byte dat2 var byte ctw con $a0 start: dat = dat + 1 addr = addr + 1 i2cwrite sda , scl , ctw , addr.highbyte , addr.lowbyte , [ dat ] pause 10 debug "Wrote: " , dec5 addr , " with " , dec3 dat , 13 , 10 i2cread sda , scl , ctw , addr.highbyte , addr.lowbyte , [ dat2 ] debug " Read: " , dec5 addr , " val: " , dec3 dat2 , 13 , 10 if dat = dat2 then debug "Write/Read Successful at " , dec5 addr , " with " , dec3 dat , 13 , 10 else debug "Write/Read Error at " , dec5 addr , "-Wrote:" , dec3 dat , " - Read:" , dec dat2 , 13 , 10 endif pause 500 goto start END

Hi skimask,

i'm pleased to say that your code worked. Thank you very much for your help ;)

Will re-write my entire code from scratch.

I have some notes here and i will see what happens.

.

Quote:

Originally Posted by ruijc

Hi skimask,
i'm pleased to say that your code worked. Thank you very much for your help ;)
Will re-write my entire code from scratch.
I have some notes here and i will see what happens.
.

Really?
That's amazing...because I did a quick search a couple days ago for 24LC512 here on THESE forums and, except for COLON-izing the one listing, practically did a cut-and-paste.
Search engine must've been broken that day...huh?

I guess i missed that one, sorry.

But thanks anyway for your help ;)

.

Greetings,

While reviewing my code i changed the I2C lines from :

I2Cread SDA,SCL,CTW,mem,[x]

to

I2Cread SDA,SCL,CTW,mem.highbyte,mem.lowbyte,[x]

to make it work.

Sorry if i'm a bit stubborn ( just trying to learn :) ), but i re-made ( yes... re-made ;) ) the search and as before almost every one mentions the I2C lines as follows :

I2cwrite SDA,SCL,CONTROL,ADDR,[DATA]

Posts like:
http://www.picbasic.co.uk/forum/show...hlight=24lc512

http://www.picbasic.co.uk/forum/show...hlight=24lc512

http://www.picbasic.co.uk/forum/show...hlight=24lc512

Including melanie's post

http://www.picbasic.co.uk/forum/showthread.php?t=587

The only one that mentions to separate the address in high and low somehow did not worked in that case

http://www.picbasic.co.uk/forum/show...hlight=24lc512

My question is just to try to understand

Why is that the i2c line ( I2cwrite SDA,SCL,CONTROL,ADDR,[DATA] ) works with other pics ( yes...all my programs with 12F675 work ) and with the 16F88 does not ? Why with this pic i need to have the address separated with high and low byte ?

Also ( question for skimask )
In post # 7 you mention :

Code:

'cause I see a few flaws in your logic in the code written a few posts back.

Can you please point where the flaws are so i can take a look at them ?

Thanks

Quote:

Originally Posted by ruijc

Why is that the i2c line ( I2cwrite SDA,SCL,CONTROL,ADDR,[DATA] ) works with other pics ( yes...all my programs with 12F675 work ) and with the 16F88 does not ? Why with this pic i need to have the address separated with high and low byte ?

Quite frankly, if it works, who cares? :)
Actually, I don't remember the answer to that at the moment. I'll remember eventually...

Quote:

Also ( question for skimask )
In post # 7 you mention :

Code:

'cause I see a few flaws in your logic in the code written a few posts back.

Can you please point where the flaws are so i can take a look at them ?
Thanks

You'll figure it out... Suffice to say there's just MUCH better ways to do some things, more reliable, faster, longer, stronger, and so on...

I've had to make some changes in my logic to work with the new I2C lines ( low/high address ) but still maintained the generic structure.

This was my priority #1

After checking if it works will study on those flaws :).

I undestand your point of "if it works, who cares", but if we leave things like that we will never get to improve the codes to be more reliable, faster and shorter ;)

Dont you agree ?

In the mean time, if you remember please let me know ;)

Thanks again
.