R66-R68 were placed there as a placeholder, just in case a resistor divider, biasing, filtering, etc was by any chance needed in a particular case. If you don´t need any of these, please ignore these three resistors.
I used STM32L4 to try to drive AD7771 in SPI mode, and tried to read and write its register mode (SPI control mode). Through reading the data manual, I found that the working mode of SPI can only choose mode 3.
I'm using AD7771 with an fully differential AMPOP. The ADC would be supplied with 3.3 V, Vref- would be tied to ground and Vcm would provide a bias for the AMPOP. In the ADD7771 analog inputs, there would be something like this:
I'm new using the EVAL-AD7771 board so I would like to know if you have a tutorial that would help me to get familiar with this board. I would like to be able to process signals from the AD7771 with a microcontroller by using the J1 connector, however…