3 wire SPI 9 bit

[espruino-discuss2]

Posted at 2016-08-10 by MichaelPralow

i want to provide a module for a specific display driver, so far it works perfectly - when using 4 wire SPI

the driver provides the option to use 3 wire SPI, but the data must be 9 bit (where the first bit determines a command or a data byte)

so far i have no luck with

// add 'it is data' to the data by setting an additional 9. left bit
      data |= (1 << 8);
      this.spi.write(data, chipSelectPin);

is there some module where 9 bit SPI is used already?

[gfwilliams]

Posted at 2016-08-15 by @gfwilliams

I'm not 100% sure if anyone uses it already... Are you using hardware or software SPI? I'm not sure about hardware, but software SPI definitely should work with 9 bits.

I just looked at the code and it seems like there is a bug that means that individual numbers being sent to spi.send are cropped to 8 bits, so that could be causing you grief? spi.write seems fine though.

If you need to use spi.send, for now, just use spi.send([data], chipSelectPin)