Re: mraa_spi_bit_per_word Problem

I don't know for sure, but I have to assume that mraa_spi_write_buf would only toggle the CS line once.  There has to be a function that sends multiple bytes between toggling the CS line.

Given your requirement, I think your code should look something like:

data[0] = 0;

data[1] = address;

mraa_spi_write_buf(spi, data, 2);

data[0] = 0;

data[1] = reg;

mraa_spi_write_buf(spi, data, 2);