AFE7950EVM: Switching between SPI lines (A, B1, B2) in Latte

Hi Team,

Is there any follow-up on this?

Hi Zeljko,

On reset only SPIA acts as SPI and other SPI buses have to be configured as SPI through SPIA. This means that SPIA must be used to bringup the AFE and configure the SPIB port. Then SPIB can be used for things such as changing the NCO or writing/reading other registers. This means that you would not be able to bringup the AFE from the FPGA using SPIB.

Regards,

David Chaparro

Hi David,

Thanks for the reply.

As I mentioned in the original post, I would eventually like to use SPI A as a channel between FPGA and AFE, so that FPGA can do the bringup and to be in full control, while having Latte in standby via SPI B.

But before any of these modifications happen, I still wanted to know if there is a command that can be issued in Latte (while it still uses SPI A to communicate with AFE via FTDI) and that can do the necessary switch between SPI A and SPI B, even if the SPI B is used only for updates of the NCOs. Can you comment on such a command if it exists and how is it used?

Finally, if what I understood from your reply above is correct, that would mean that practically SPIA is the only complete SPI, while SPI B1 and SPI B2 can only have a partial SPI functionality and can never enable full communication as SPI A is supposed to be doing it. In other words, regardless what is the source (Latte on PC, or FPGA, or even an micro-controller) when AFE is the target the full blown communication should always happen via SPIA, and never via auxiliary SPIs (B1 and B2), as those can only enable partial reconfiguration of AFE. Can you confirm if my understanding here is correct?

Kind regards,

Željko