Serial Peripheral Interface

Can you explain where LinuxCNC fits into this system?

I rather think that you are confusing data-rate with latency. LinuxCNC typically transmits very little data (dozens of bytes) but it does it every 1mS +/- 25uS.

I am certain that we can help you with your project (I did 15 years postdoctoral research, so have pedagogic inclinations) but I question your underlying architecture.

There is a bitbanged SPI component here:

github.com/LinuxCNC/linuxcnc/blob/master...onents/max31855.comp

Might be a starting point.

monkey_biz wrote:

Wouldn't I be able to just use the SPI hardware provided on the beagle bone for this as opposed to do a bit banged SPI? I am doing my best to get acquainted with linux but it is proving to be tough

In theory, yes.
You would need a simple HAL driver to get values from HAL and put them into the BB SPI registers.

Writing HAL drivers can often be surprisingly simple. Do you have any C-code examples using BB SPI?

Be aware that there is now considerable divergence between Machinekit and LinuxCNC. I you are using Machinekit then you may need to get your answers from their forums.

The realtime layer is not about speed so much as well-defined time-intervals.
G-code interpretation is non-realtime, the G-code is turned into a sequence of simple movements. These movements are converted to a set of axis positions and it is these positions that are transmitted by the realtime layer. Every 1mS a new set of positions comes out of the motion module, and also every 1mS the current hardware position and inputs are processed.

Basically, only the parts of LinuxCNC that "touch" hardware are realtime.