I have used the Cygnal (www.cygnal.com) C8051F126 part. It has onboard SPI port that I used to communicate with a serial interface graphics LCD module. I used this part with 22.1184 MHz crystal and with the 1X oscillator divider to the bus cycle clock this puppy can process code fast. I ran the SPI at busclk / 8 == 2.7648 MHz. (Note it can clock faster if the destination can talk as fast). In the application I was working with I found that the interrupt overhead to support the SPI at this rate was too high so I used the SPI port to do the bit level protocol and ended up polling the SPI byte complete status bit to know when to move on to the next byte. Overall I was VERY happy with the 'F126, how it worked, the Cygnal support, and the Cygnal IDE and debugger that supported the on-chip debug hardware that is on every Cygnal processor. (Yes you get hardware breakpoints right in the target product if you provide access to the JTAG port on the circuit board.

Michael Karas