Nexys Video SDK for DSPI Transfer

[Roy0215]

Hi,

I'm now verify my spi slave design on the Nexys Video. So I refer to the DSPI programer's reference manual.

The shot below is the API function DspiGet from the manual.

 

Two underlined definitions of parameter bFill seem different and it makes me confused.

'level of MOSI during transaction' seems to be a flag.

But the latter description shows bFill is the data to be sent.

Which one is correct?

Besides, can I use DspiGet function without bFill? I just want to read the default data from the registers in my design.

Best,

Roy

[zygot]

I've not looked at this interface before but I'd say that you have good reason to be confused as this appears to be a typo. bfill in the function call is of type BYTE which clearly is not going to be TRUE or FALSE. Hopefully, someone from Digilent will take interest in time to help you.

[jpeyron]

Hi @Roy0215,

I reached out to a design engineer about this forum thread and they responded that

"whenever you do an SPI transaction you have to shift an equal number of bits in both directions (out on MOSI, in on MISO). The bFill parameter specifies a constant 8-bits to shift out on MOSI each time a byte is transferred. With DspiGet every time a byte is transferred the same data is shifted out. If you want to shift out a non-fixed pattern on MOSI and receive data then you need to use the DspiPut function instead of DspiGet."

We are still clarifying the verbiage for the DSPIGet function attached above.

thank you for your patience,

Jon