pi_spi.py

import spidev 

bitrate = 50000000

print(f'rate {bitrate/1e6}MBit/s bit period should be {1000000000/bitrate}ns')

spi = spidev.SpiDev()
spi.open(0, 0)
spi.max_speed_hz = bitrate 

for i in range(1000000):
    spi.xfer([12, 14, 95])

spi.close()