What's the maximum speed for SPI on an STM32F4 board running netmf?

I’m working on a project that requires me to read from an 18bit ADC (LTC2364-18) connected via SPI at 20Mhz. Yes, Mhz not kHz.

I was able to connect to my SPI flash at 12Mhz using the wonderful MX25l3206BlockDriver and TinyFileSystem code.

If I can’t read data at 20Mhz in managed code, what’s the easiest way to do this in managed code? RLP or firmware? I’m compiling my own firmware but I’m not a CPP guy. So any sample code would be appreciated.

20MHz SPI bus speed is fine

I love GHI. I’ll post code for the ADC when I have it.