SPI issues on CS line

Started by vnv, November 22, 2022, 06:00:18 pm

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Hello everyone,

there are issues on CS line for SPI which are very very strange.

So I have a small code running in python which sends out 0x40 command and does the read.
Problem is that CS bounces down/up couple of times before doing real clocking which puts device in some bad state because devices doesn't expect CS to bounce for no reason.

Here is the code:

#!/usr/bin/env python

import os
import sys

if not os.getegid() == 0:
    sys.exit('Script must be run as root')

from time import sleep
from pyA20Lime import spi

spi.open("/dev/spidev1.0", mode=0, delay=0, bits_per_word=8, speed=500000)

while True:

    value = spi.read(2)
    print value



And here are the images what goes on,



Does anyone knows what could this be and why would CS pin bounce before actual clock cycles start to go out?