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ADS1100 send only 0xFF byt's

schneider jean-marie
Prodigy 170 points

Other Parts Discussed in Thread: ADS1100

Hello,

 

I am developping an application with a presure sensor and would like to use ADS1100 as A2D convertor. On the same I2C bus I have an EEPROM which work fine.

With the ads I had trouble :

  • during initialisation (send the configuration byte), I see nothing wrong (ADS send the ACK as expected)
  • config is as follow :
    • PGA0 = 0 and PGA1 = 0 : gain = 1
    • DR0 = 1 and DR1 = 1 : 8 samples per second
    • SC = 1 : continuous mode
    • other = 0
  • when I start a read operation, ADS send the ACK and then the 3 bytes.

But all bytes equal 0xFF, even the config one.

Analog input is 4.1 V (Vin- = 0 V, Vin+ = 4.1 V).

 

That very disapointing and I am unable to see what is wrong. Any idea would help !

 

Thanks you

Jean-Marie

  • 0
    Prodigy 170 points

    I did not post in the correct forum !!

     

    Is it possible to move it in the correct one (data converters) ?

     

    Thanks

    Jean-Marie

  • 0 in reply to schneider jean-marie
    TI__Guru 55466 points

    Hi,

    When trying to perform the read operation from the ADS1100; after sending the I2C address slave byte, is the read/Write bit set high to be able to read data form the ADS1100?  If after sending address byte, this bit is low, then the ADS1100 is configured to be written to; and this could explain why the SDA line is left high.

     Let me know if this helps,

    Thank you,

    Regards,

    Luis

     

  • 0 in reply to Luis Chioye
    Prodigy 170 points

    Hello Luis !

     

    Thanks you for your answer ! That exactly my issu... Problem is coming from my code where I define adresse of ADS in the write mode. And when I would like to read the conversion valueI add 1 to this :

    #define ADRESSEADS 10010010

    Pression[0]  = ADRESSEADS +1;

     

    after this operation Pression[0] is till equal to 10010010 ! I modify the code to

     

    unsigned char AdresseADS;

     

    and initialise it at the beginning of the main() function. So problem is solves !

     

    Thanks again

    Jena-Marie