I2c write&read

[MINHLE]

thank Gusse,

i replaced data address (I: in this case) by WORD . . and/or change R from 10K to 6K. ..it doesnot work.

(in the data sheet of 24lc256 dooesnot mention anything data address.

VOLTAGE drop across: R_SCL (10K or 6K) : ~5V (unchanged)
R_SDA (10K or 6K): ~2.5V

!! is it possible the EEPROM: DEATH??

[Gusse]

Hi MInhle,

If you are running with internal oscillator then speed is 4MHz, not 20MHz. Also you should tell that to compiler.

14.2.6 INTERNAL 4 MHZ OSCILLATOR
The internal RC oscillator provides a fixed 4 MHz
(nominal) system clock at VDD = 5V and 25°C, see
“Electrical Specifications” section for information on
variation over voltage and temperature.

DEFINE OSC 4

OSC: INTRO CLOCKOUT

14.2.7 CLKOUT
The PIC16F62X can be configured to provide a clock
out signal by programming the configuration word. The
oscillator frequency, divided by 4 can be used for test
purposes or to synchronize other logic.

CLKOUT is RA6, which is also your I2C data pin. Disable CLKOUT or change I2C data pin to other IO.

If you are not using comparator then disable those.

CMCON = 7

I hope these modifications will bring up some life to your EEPROM interface.

BR,
-Gusse-

[MINHLE]

hello GUSSE,

i got a BONUS now. the led is on (pin2 only) and flash

i lookk for error in teh program and let u knoow later

thanks for your help

[MINHLE]

HI Gusse,

the modifications were made.
as indicated.

defined OSC 4 ;no effect: ( INTCLOUT is set in the fuse window)
SDA PORTA.3
SCL PORRT.4
......

R_SDA & R_SCL: 4.5k
a led on portb flashed is due to error that i cannot see where it comes from


not write nor read. i assume EEPROM???

[Gusse]

Hi MInhle,

Below is very simple I2C write and read test script.

<code><font color="#000000">CMCON = 7
TRISA = %11000000
TRISB = %00000000

SDA                 <b>VAR </b>PortA.3
SCL                 <b>VAR </b>PortA.4     
LED                 <b>VAR </b>PortB.0     <font color="#000080"><i>'Indicator LED (change if needed)    

</i></font>I2CDeviceEEprom     <b>VAR BYTE    
</b>I2CAddressEEprom    <b>VAR WORD
</b>TEMP1               <b>VAR BYTE
</b>TEMP2               <b>VAR BYTE

</b>I2CDeviceEEprom=$A0     <font color="#000080"><i>'DeviceID 10100000 = $A0 = %1010 A2=0, A1=0, A0=0 R/W=0

</i></font><b>DEFINE </b>OSC 4
    
Main:
    I2CAddressEEprom = 0
    TEMP1 = 1
    <b>GOSUB </b>Write_I2C
    <b>PAUSE </b>10
    <b>GOSUB </b>Read_I2C
    <b>IF </b>TEMP1 = TEMP2 <b>THEN
            HIGH </b>LED        <font color="#000080"><i>'If OK then 0.5s LED blink
            </i></font><b>PAUSE </b>500
            <b>LOW </b>LED
        <b>ELSE
            HIGH </b>LED        <font color="#000080"><i>'If FAIL then 2s LED blink
            </i></font><b>PAUSE </b>2000
            <b>LOW </b>LED
    <b>ENDIF
    GOTO </b>Main   
    
Write_I2C:
    <b>I2CWRITE </b>SDA, SCL, I2CDeviceEEprom, I2CAddressEEprom,[ TEMP1 ]
    <b>RETURN

</b>Read_I2C:
    <b>I2CREAD </b>SDA, SCL, I2CDeviceEEprom, I2CAddressEEprom,[ TEMP2 ]
    <b>RETURN
    
END
</b></code>

If write and read are successfully executed then LED will blink for 0.5s.
2s LED blink will be an indication of fail.

BR,
-Gusse-

[MINHLE]

hello Gusse,

I copy you program. run ---> the light is solid.,



i tr to put direcly data into EEProm, the out put is whatever,,,

i.e.

i = 0 ; data address
b0 = $2a ; data to be stored

i2cwrite .......... i, [b0]

b0 = 0
i2cread .........i,[b0]

run ----> whatever... output (BONUS ONLY)

i have to replace the EEPROm
thanks for your time

regards,

[Gusse]

Hi,

Sorry, I had one bug there. One pause missing.

<code><font color="#000000">CMCON = 7
TRISA = %11000000
TRISB = %00000000

SDA                 <b>VAR </b>PortA.3
SCL                 <b>VAR </b>PortA.4     
LED                 <b>VAR </b>PortB.0     <font color="#000080"><i>'Indicator LED (change if needed)    

</i></font>I2CDeviceEEprom     <b>VAR BYTE    
</b>I2CAddressEEprom    <b>VAR WORD
</b>TEMP1               <b>VAR BYTE
</b>TEMP2               <b>VAR BYTE

</b>I2CDeviceEEprom=$A0     <font color="#000080"><i>'DeviceID 10100000 = $A0 = %1010 A2=0, A1=0, A0=0 R/W=0

</i></font><b>DEFINE </b>OSC 4
    
Main:
    I2CAddressEEprom = 0
    TEMP1 = 1
    <b>GOSUB </b>Write_I2C
    <b>PAUSE </b>10
    <b>GOSUB </b>Read_I2C
    <b>IF </b>TEMP1 = TEMP2 <b>THEN
            HIGH </b>LED        <font color="#000080"><i>'If OK then 0.5s LED blink
            </i></font><b>PAUSE </b>500
            <b>LOW </b>LED
        <b>ELSE
            HIGH </b>LED        <font color="#000080"><i>'If FAIL then 2s LED blink
            </i></font><b>PAUSE </b>2000
            <b>LOW </b>LED
    <b>ENDIF</b>
    <b>PAUSE </b>1000        <font color="#000080"><i>'PAUSE ADDED</i></font>
    <b>GOTO </b>Main   
    
Write_I2C:
    <b>I2CWRITE </b>SDA, SCL, I2CDeviceEEprom, I2CAddressEEprom,[ TEMP1 ]
    <b>RETURN

</b>Read_I2C:
    <b>I2CREAD </b>SDA, SCL, I2CDeviceEEprom, I2CAddressEEprom,[ TEMP2 ]
    <b>RETURN
    
END
</b></code>

Now it will blink.

BR,
-Gusse-