AD5678 and AD7193: Problem while using simultaneously.

Hi Mahendra,

Can you please prodive a schematic so we can see how you are interfacing to both. Are you using seperate digital interfaces?

Regards,

Padraic

Hi padraic,

      i have attached schematic.

among 2 only 1 AD7193 is placed on board 1 place is left open. External amplifier ckt circuit was isolated from AD5678 for testing purpose.

Same digital interface is used for all 3 ic's.

i also replace AD5678 but result is same. 

same interface working properly for LPC2378.

Hello Mahendra,

the connections/decoupling to the converters looks good.  It is unclear from your email whether the problem is due to the serial interface or something else. Can you confirm that you can read and write from either the ADC or DAC without corrupting registers in the other converter. For example, if you write to a register on the ADC, can you read back the same register to confirm that the correct value was written to the register. Can you also check the DAC registers to confrm that their contents were not altered by the write to the ADC.

You say that the ADC outputs all 1s when the DAC code is less than 32500. When the ADC outputs all 1s, can you read back the ADC's on chip registers to check whether the register values are correct or whether they are corrupted. Can you probe the reference input to the ADC along with the power supplies to the ADC to ensure that they are still at the expected value while the ADC outputs all 1s. Finally, probe the analog input to the ADC during the fault condition to check that the input has not changed.

Regards,

Mary.

Hello Mary,

      Thanks for reply.

      The same code and circuit are working for DAC channel 7. there is no probe but if i change DAC channel problem starts. Also same code and circuit are working fine in LPC2378 for all channels.

      I will try to read the ADC and DAC register value. i have attach code with email please check if there is any problem.

Thanks

Mahendra

Hello Mary,

            I checked all points mentioned by u.

            in that the setting of configuration register of ADC are corrupted. As far setting value is 0x041FD8 but after fault they are corrupt like

  0xF01FD8, 0xEF1FD8, 0x4B00B1, 0xB580B1 etc.

            All power supplies are at expected value. ADC input ok. DAC is working even after fault.

Hi Mahendra,

is CS of the AD7193 high when you write to the DAC. Is it possible that the data being written to the DAC is also being loaded to the config register of the AD7193?  Are other registers of the AD7193 corrupted (mode register, etc)?

Regards,

Mary.