SPI communication rising edge of clock

[Milad]

Hello,

How can I have the rising edge of my clock to be less than 40nm? I am currently using a 4GHZ clock cycle for my SPI communication? Thank you.

[Wojtek]

I don't know what is the time of edge rising, but according to reference manual SPI Master on nrf51822 allows max data rate of 8Mbps