problems working with 24C512

[shaiqbashir]

thanks for your help

mat jensson you have raised a nice point here. I have tried almost every possibility in my coding as well as in my connections, but its not working at all. Please explain me your idea,
i mean what do u mean by marking the read bit? and how can i specify two addresses, can u explain me a bit.

One more thing that i want to share with u all. I get different numbers as output when i connect SDA SCL on different ports.


when i have

SDA = portB.1
SCL= portB.0
output= 2

SDA = portD.1
SCL= portD.0
output= 2

SDA = portC.1
SCL= portC.0
output= 8

I just couldnt get it.



Regards,

Shaiq Bashir

[Bruce]

Make sure you have A0,A1,A2 on your EEPROM at ground.

Make these few changes to your existing code.

CNTRL VAR BYTE ' added for control byte
CNTRL = %10100000 ' value of control byte

EWrite:
I2CWRITE SDA,SCL,CNTRL,Addr,[E_ByteOut] ' Write out the byte
Pause 10 ' Delay 10ms after each write
Return

ERead:
I2CREAD SDA,SCL,CNTRL,Addr,[E_ByteIn] ' Read in the byte
Return

Does this work?

[mister_e]

For the really last time, i'm still sure your SDA/SCL are reverted and/or you don't have the right Pull-Up resistors on SDA & SCL, and i also endorse the A<2:0> setting.

OK why i stick to it ?

1. Because i already used something like that in one of my Radio Decode Dongle to confirm the end-user haven't swap the SDA/SCL line when reading in circuit the target I2C EEprom inside the radio.

2. Let's say i use a at24c1024 here with the following...

        CONT    CON %10100000
        ADDR    VAR WORD
        ByteA   VAR BYTE
        
        SDA     var PORTC.4
        SCL     var PORTC.3        
        PAUSE   500
        
Start:
        for addr = 0 to 10
                ByteA=ADDR.LOWBYTE
                I2CWRITE SDA,SCL,CONT,ADDR,[ByteA]
                PAUSE 20
                NEXT
                
        FOR ADDR=0 TO 10
                I2CREAD SDA,SCL,CONT,ADDR,[ByteA]
                HSEROUT ["ADDR=", DEC ADDR,_
                         "   ByteA=", DEC ByteA,13,10]
                NEXT

I got the expected..

ADDR=0   ByteA=0
ADDR=1   ByteA=1
ADDR=2   ByteA=2
ADDR=3   ByteA=3
ADDR=4   ByteA=4
ADDR=5   ByteA=5
ADDR=6   ByteA=6
ADDR=7   ByteA=7
ADDR=8   ByteA=8
ADDR=9   ByteA=9
ADDR=10   ByteA=10

But now if in my code i swap the SDA, SCL definition to...

        SDA     var PORTC.3
        SCL     var PORTC.4

i got...

ADDR=0   ByteA=8
ADDR=1   ByteA=8
ADDR=2   ByteA=8
ADDR=3   ByteA=8
ADDR=4   ByteA=8
ADDR=5   ByteA=8
ADDR=6   ByteA=8
ADDR=7   ByteA=8
ADDR=8   ByteA=8
ADDR=9   ByteA=8
ADDR=10   ByteA=8

Amazing how close to your problem it is huh?

Let's do it much funky now... let's totally remove the EEPROM from the circuit. With the pull-up installed i still have all those 8, without pull-up i got all 0.

Now, with the right code, but the EEPROM have the wrong A<2:0> setting...
i got all 16, reverted... all 8.

Enjoy!

[sayzer]

Let this be the schematic for reference.


<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=2625&d=1212050571" >