spi_test_speed.lua

-- clock_div: SPI clock divider, f(SPI) = 80 MHz / clock_div
function spi_test(clock_div)
  
  spi.setup(1, spi.MASTER, spi.CPOL_HIGH, spi.CPHA_HIGH, 8, clock_div, spi.FULLDUPLEX)
  
  for n=0,256 do
    r = { spi.send(1, n) }
    --print(n, r[2])
    if n > 0 and ((n-1)*2) % 256 ~= r[2] then print("ERROR!") ; return end
    end
  
  print("Test OK! :)")
  
end

-- test with ATtiny 2313:
-- > spi_test(19)
-- ERROR!
-- > spi_test(20)
-- Test OK! :)