I have the below python script which I am using to collect data from a microcontroller using SPI communication. That part is working fine, however, now I am trying to implement CRC function from a c file.
import ctypes
lib = ctypes.CDLL( '/home/pi/serial_communication/crc.so' )
lib.crc32Word.argtypes = ctypes.c_uint32, ctypes.c_void_p, ctypes.c_uint32
lib.crc32Word.restype = ctypes.c_uint32
INTERRUPT_GPIO = 12
pi.set_mode(INTERRUPT_GPIO, pigpio. INPUT )
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):
data = [ 0 ] * 1024
spi.xfer([ 0x02 ])
with open (output_file_path(), 'w' ) as f:
for x in range ( 1 ):
spi.xfer2(data)
values = struct.unpack( "<" + "I" * 256 , bytes(data))
C = lib.crc32Word( 0xffffffff ,data, len (data))
f.write( "\n" )
f.write( "\n" .join([ str (x) for x in values]))
print (C)
cb1 = pi.callback(INTERRUPT_GPIO, pigpio.RISING_EDGE, spi_process)
while True :
time.sleep( 1 )
The C function that I am trying to invoke from the python script is
crc32Word(uint32_t crc, const void * buffer , uint32_t size)
But when I run the above script, I receive error as:
Exception in thread Thread - 1 :
Traceback (most recent call last):
File "/usr/lib/python3.7/threading.py" , line 917 , in _bootstrap_innerself.run()
File "/usr/lib/python3/dist-packages/pigpio.py" , line 1213 , in run cb.func(cb.gpio, newLevel, tick)
File "2crc_spi.py" , line 50 , in spi_process
C = lib.crc32Word( 0xffffffff ,data, len (data))
ctypes.ArgumentError: argument 2 : < class 'TypeError' >: wrong type
One way to solve this is to use data = bytes([0]*1024) . But if I use this method, the file stores 0s even if I am actually receiving data correctly (checked using logic analyzer).
Can someone please help? Thanks.