I have a situation where I do not want to use a TIMER and DMA channel to feed the McBSP transmitter, but would like to use the BRG (Baud Rate Generator) to send 12-bit or 16-bit words at a steady rate. The data can be all zeroes (0x0000) or anything else, so that's why I prefer to save the resources and bandwidth by avoiding a TIMER & DMA. I also need to use the SPI mode, a.k.a. CLKSTP=2.
So far, I have not been able to get the McBSP transmitter to send data from an empty transmit register. This makes some sense, because the McBSP peripheral usually knows that nothing is being updated in the output data register. I cannot quite determine from the documentation whether it should be possible to have the McBSP simply send zero-content data words without some mechanism to continually store 0x0000 in the output register.
Can anyone shed some light on whether it is possible to achieve what I describe?
If it is possible, then is SPI CLKSTP mode perhaps causing problems (due to the cross-connect between transmit and receive clocks and framing)?
Also, can anyone give example register settings to achieve the above?
I have a hunch that SPI mode is combining with my receive settings to prevent things from working, but I cannot be sure.
Since the McBSP transmitter is generally triggered to send whenever data is stored in the output register, I am assuming that I must change some setting so that this trigger requirement is defeated and the BRG frame sync is used instead. Any information would be appreciated!