Question: Can I program multiple SigmaDSPs in parallel using one USBi?
Answer: Yes, you can string together multiple SigmaDSPs on one or more PCBs and control them with a single USBi.
If all of the SigmaDSPs in the chain are running the same program, you can set them all to the same address and connect the I2C lines (SDA and SCL) in parallel to all of them.
Here's an example of where we set up 6 EVAL-ADAU1701MINIZ boards in the lab connected to a single USBi via a ribbon cable with header connectors. In this case, you set all of the SigmaDSPs to the same I2C address and use a single SigmaStudio project containing a single SigmaDSP IC. When you Link-Compile-Download, the same data will be sent to all of the SigmaDSPs on the I2C bus. As long as the cable is relatively short and the signal integrity of the signals is maintained, this works just fine.
In the case where the program needs to be different on each SigmaDSP, you need to make a SigmaStudio project with multiple ICs. You can either set different I2C addresses for each SigmaDSP, or use different SPI latches for each SigmaDSP, or use a combination of I2C and SPI simultaneously.
Here is a picture of our internal USB testing board, which contains two ADAU1701 SigmaDSPs. The communications protocol can be easily changed for each SigmaDSP between I2C or SPI, and the addresses and latch lines are also configurable.