AD7920 12-bit ADC lab

Question

I set up the AD7920 12-bit ADC lab but do not get the screens that are shown. Here are my screens:

layout:

Why do I not get any output from the MISO logic analyzer ? 
 Could the chip layout be backwards from the web layout, as the "1" and "8" in the above picture are on the Right. 
 Thus, is this chip layout as: 
 top 5 6 7 8 bot: 4 3 2 1 
 whereas in the web instruction it is 
 top 8 7 6 5 bot 1 2 3 4 
 Also, where should I place the 1+ /1- leads of the oscilloscope to read the input voltage ? 
 I placed the 1+ at W1 and 1- at ground, but the oscilloscope shows zero voltage: 
 
 Thanks !

andreeapop · Answer

Hi Ron, 
 
 I don't see any falling edge of the CS signal in your screenshot. This should trigger the conversion. I think the SPI is not configured correctly in the logic analyzer. 
 Is the same value read even if you change the output value of the signal generator? Could you please check the wiring again, because it seems like the ADC is reading a voltage equal to its Vref and I think maybe that's why it decodes 0xFFFF. 
 
 Regards, 
 Andreea

andreeapop · Answer

Hi Ron, 
 I tried to redo the setup with the newest Scopy version. 
 This is my result in Logic analyzer when the signal generator is set to 1.5V. It is not the same value as in the activity, but if decoded using the formula in the documentation, the hex value corresponds to 1.558V which is an acceptable result. 
 
 These are my Logic Analyzer settings, with a SPI Decoder enabled

The CS signal is created in Digital IO Tool. After you make all the other instrument settings, you can detach Digital IO tool (find this option in Preferences menu, it it is not already active on your device).Enable the Digital IO, clicking on Run, then with DIO0 set as output, alternatively click on 1 and 0 to change its state and create the CS signal.

If you are still not able to receive data from the ADC after these steps, your AD7920 may be damaged (maybe as a consequence of the reverse wiring from the beginning). I tried this experiment with two different AD7920 and one of them was also broken. What I noticed and helped me determine that the IC is broken was that the VDC Measure of the M2K Power supply was not accurate, reading ~2.5V instead of 3V which I set. 
 Regards, 
 Andreea