Good resource to understand HAL

Hows it going guys,

I just picked up a MESA 7i76e and got it up and running no problem. I have have proceeded with the PnCConfig and am able to run linuxcnc. I am still pretty new to Linuxcnc and was wondering if someone could point me in the right direction in understanding HAL. I am having a hard time understanding it conceptually. I know that the .hal file is a configuration file but thats about it. Is it some kind of configuration file for linuxcnc so it knows what board you are using, how to connect to it, and gives a layout of all the pins ? Am I on the right track? Any more resoruces would be awesome. Thanks for reading !

HAL is infrastructure that makes sharing specific information between programs possible and easily reconfigurable.

ie the mesa board program shares data (via HAL) with the linuxcnc machine's I/O controller program.

It's best analogy is electrical connections.

The manual is surely the best source of information.
Actually playing with simple (non machine controller) examples may be a good way to learn.

Ok so since the MESA is an FPGA card at the end of the day the HAL file is a way to tell LinuxCNC what is connected to where and these "connections" can be managed as one sees fit.

Andy,

Thanks for the reply I think I understand. This may be a step to far but could you brake down the syntax of the HAL line you included that would be a game changer or point me in the right direction as to where i can learn the syntax of HAL.