It sounds like you are talking about synchronous communication - no start or stop bits. If that is the case, you can use the SPI function of the processor.
Hi skyjumper,no UART :-)I need to generate a signal for driving digital modell locomotives (not DCC but Motorola-Märklin). So my other end of the communication is a decoder chip inside the locomotive. I have a rough manual how to generate the frames with a serial line at 19200 bit/s but you have to do some strange timing things to get the right signal. I thaught that it is better to generate the signal without that strange things but for this you "might" have to send the frames with a non-standard bit rate (s. http://modell-zug.com/Support/HowToArticles/DigCtrlSys/DigitalTransmission.htm). I read some documentation where they don't use exactly 4800 bit/s... but I'm not sure.Regards, Holger