CC2500: CC2500

Not sure I understand your question. The data you want to transmit is either written byte by byte over SPI to a FIFO and then transmitted on the air (RF) using different modulation formats, as listed in the data sheet (OOK, ASK, FSK, GFSK, MSK). This is called normal mode. You can also configure the radio to use serial mode (Synchronous or Asynchronous).
In asynchronous mode the CC2500 modulator samples the level of the asynchronous input 8 times faster than the programmed data rate
In the synchronous serial mode, data is transferred on a two wire serial interface. The CC2500 provides a clock that is used to set up new data on the data input line or sample data on the data output line.

Siri