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AD7982 SPI help

Question asked by JPablo on Nov 17, 2012
Latest reply on Nov 22, 2012 by jcolao

Hello,

We've been trying to test our ADC by interfacing it with a PIC32 microcontroller (PIC32MX795F512L) through the native SPI Channels.

We've connected everything as /CS mode 3 wire without busy indicator (digital side) and as the reference design with a AD4941 driver (analog side) but are unable to get anything other than a 0 result on the SDI in the microcontroller.

 

connections

Vdd = 2.5V (regulated)

Vref = 5V

Vio/SDI = 3.3 V (digital logic, regulated)

SCK = SPI clock on MCU

SDO = SDI on MCU

CNV we've tried connecting it to SS on the chip or a pin controlled by us using the timing diagram in the 7982 datasheet.

 

 

Right now we have a 1V offset Sine wave in an attempt to test the chip but as mentioned before have been unsuccesful. The microcontroller is acting as a SPI master and have tested the SPI side functionality in a loopback succesfully so we know its not the microcontroller.

 

Any help will be MUCH appreciated.

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