Andy, thank you for the hint! I was somehow under the impression
that I need to adhere the 10 to 12 bits distance in both ways which
seems kinda silly, because it would introduce a unnecessary gap
between transmission to the CMX981. I guess this simplifies my life
a little :)
Concerning FSB vs. CBUS: I already have a CML (PE0002) device
connected via CBUS to CMX981 which supplies the transmission clock
signal. The connection is not reliable for clock speed greater than
2Mhz. Additionally, I always have to give the address before sending
data or receiving data. On plus side, it is SPI compatible. Later I
may use the gumstix SPI port to connect to the CBUS port and use it
simply for configuration. As you can see in the CMX981
block diagram, the device has one CBUS port switchable to FSB
and two additional FSB ports. Using the FSB port 3 and enabling TX
and RX data paths in the CMX981, I am able to simply send data to
device without a register address and the device immediately
processes the data according to the modulation scheme and delivers
baseband I/Q data to another device (or loops it back to the
gumstix). As I wrote before, the serial clock for FSB transmission
can be set up to 9.126 Mhz.
I am already in contact with CML and they suggested to use the
OMAP's McBSP for controlling TX and RX data, that's why I started
this thread initially.
So I am off reading Linux Device Drivers.