pi3_1mhz_spi.py

import spidev
import time
spi = spidev.SpiDev()
spi.open(0, 0)

# getting pi 3 or later (bcm2835 +) to generate 1 MHz spi clock is possible, but stupid:
# setting to 1.6 MHz math works out generating a 1 MHz clock output.. 
hz = 1600000
i = 0

while True:
    spi.max_speed_hz = hz
    d = [0xFA] * 4096
    spi.xfer(d)
    #print('hz = {}, i= {}'.format(hz, i))
    #hz += 100000
    #i = i + 1
    #if hz >= 2000000:
    #    hz = 100000

    time.sleep(0.33)