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doceme / py-spidev

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bits_per_word in RasPi problem #6

Closed guibe80 closed 10 years ago

guibe80 commented 11 years ago

Hi there:

I'm using the SpiDev to connect my device and I need to send 16 bits words. I'm using the option "bits_per_word=16". However, if I put a value above 9 bits I recieve the error "IOError: [Errno 22] invalid argument".

I'm wondering if this is a problem of either the wrapper or the RasPi. I thought that the RasPi register were only 8 bits but it's working with 9 bits words.

Thanks for any feedback!

Mario B.

doceme commented 10 years ago

I don't have an RPi, so I can't say for sure. Perhaps you could take a look at the lower level kernel SPI driver (broadcom?) and see if it's possible to use 16 bit SPI transfers. It will only work if the underlying hardware and kernel driver support it.

gborque commented 10 years ago

I'm having the same problem using the Raspberry Pi as SPI master, it has been a tremendous headache. As you can see in the RPi wiki web page, the Raspberry Pi only supports 8 bits per word http://elinux.org/RPi_SPI