Hmmh, it could be done, but it'll be a bit tricky, especially the requirement to play and scan the RF simultaneously might lead to software complexity. I'd probably start by examining how to use the onboard SPI port to most benefit. For example, if your VS1000 CPU master clock is 48 MHz, you could set 191 to the SPI clock divider so you'd get 125 kHz SPI clock from the SCLK pin (48 MHZ / (191+1)*2). Using the SPI peripheral in 16-bit mode you'd get an interrupt from the SPI controller once per 16 bits, which is 7812.5 Hz. That would certainly be manageable. Your code can then handle 16 bits received from the MOSI pin by the SPI hardware. But I'm not sure how cycle accurate restarting the SPI transfer after each 16 bits in the interrupt handler is, you should test it.