Query about eval - cn 0326 kit

Hi Everyone

I have been trying to interface eval-cn-0326 kit which uses AD7793. So far i am able to communicate well with the chip , I am able to read the id and read whatever value i have written in the mode and configuration register.

But the problem arises when i try to read the data register. I always get a constant code of 0x800000 when the ph sensor is connected with it(status register show that there is no error).

If the pH sensor is removed , i get 0xFFFFFF(Seems right to me) and also the error bit in status register says that all the bits have been clamped to FF.

My setup is 
No temperature sensor on J2 (4.7k resistance in place of R1), pH sensor on J1

My observations are : 

No voltage between TP2(AIN1+ ) and GND. 

Please help me out of this , its very urgent. 

If you want to confirm anything else , please let me know.


  • My registers settings are as followed

    Configuration Register : Bias Disabled , Gain : 1 , Bipolar , External Reference , AIN1+ , AIN1- , BUffered Mode
    Mode register : Freq adc : 16.7Hz , Internal 64Khz clock , Single conversion mode

    Then i read the data register by sending 0x58 to the chip