Issue while using ctypes in python

[GiggsB]

Hi,

I just wanted to give an update (I wasn't able to work on this issue for some time) that I was able to solve the issues. I used a python library called zlib instead of calling a C function. Using a python library looked easier. I also worked using @deanhystad's suggestion that data was actually immutable. So, I was able to update my python script accordingly and was able to make it work. I am adding my code just in case someone else faces similar issue.

import datetime
import os
import struct
import time
import pigpio
import spidev
import zlib

INTERRUPT_GPIO=25

bus = 0
device = 0
spi = spidev.SpiDev()
spi.open(bus, device)
spi.max_speed_hz = 4000000
spi.mode = 0

pi = pigpio.pi()
if not pi.connected:
    exit()

pi.set_mode(INTERRUPT_GPIO, pigpio.INPUT)

C=0
 
def output_file_path():
    return os.path.join(os.path.dirname(__file__),
               datetime.datetime.now().strftime("%dT%H.%M.%S") + ".csv")
 
def spi_process(gpio,level,tick):
    print("Detected")
    data = bytes([0]*1024)
    spi.xfer2([0x02])
    with open(output_file_path(), 'w') as f:
        t1=datetime.datetime.now()
        for x in range(1):
            recv = spi.xfer2(data)
            values = struct.unpack("<" +"I"*256, bytes(recv))
            C = zlib.crc32(bytes(recv))
            f.write("\n")
            f.write("\n".join([str(x) for x in values]))
        t2=datetime.datetime.now()
        print(t2-t1)
        print(C)

input("Press Enter to start the process ")
spi.xfer2([0x01])

cb1=pi.callback(INTERRUPT_GPIO, pigpio.RISING_EDGE, spi_process)

while True:
    time.sleep(1)

Thank you so much for all your help.