Python IOError: [Errno 90] Message too long, Passing long list to SPI function
17:07 18 Nov 2015

I'm programming my A13-OLinuXino-MICRO using the provided pyA13 0.2.2 SPI driver to send data to an LCD. Ideally I would like to send a list containing 320*240*2 (320*240 pixel 16 bits per color) bytes to be written in one continuous write command to be speed efficient. The drivers in spi.c and spi_lib.c had an 8bit tx_len which limited me to 256 bytes so I modified them to 32bit which worked but now I receive an error when I try to pass a list that is more than 4096 values long in my spi.write(data[:]) function. Below is the code I'm using to fill the screen with a solid color that is 16 bits:

def FillScreen(c):
    LCD_SetPos(0, 0, 239, 319)
    ch = c>>8 & 0x00FF
    cl = c & 0x00FF
    d =[]
    for x in range (0,76800):
        d += [ch, cl]
   spi.write(d[:])

This is the error I get when I run the function:

Traceback (most recent call last):
  File "lcd.py", line 205, in 
    FillScreen(0x00FF)
  File "lcd.py", line 200, in FillScreen
    spi.write(d[:])
IOError: [Errno 90] Message too long

The piece of code that is giving me this error is contained in spi.c

/* Send data */
    if(spi_write(fd, tx_buffer, tx_len) < 0){
        return PyErr_SetFromErrno(PyExc_IOError);
    }

Is there any way that I can pass a longer message to the spi.write function? I'm very new to python but quite comfortable with C, go easy on my code please... Also, I have tried looping smaller messages to fill the screen but that takes too long. Any help would be appreciated.

Thanks, Michael

python c spi ioerror