This is a simple device driver for the PIUIO arcade input board that allows for reading inputs and controlling outputs from userspace programs. It is coded assuming the default configuration where four sets of inputs are attached to a multiplexer, and it fetches all four sets for a single read operation. (In some circles, this is referred to as the "r16 kernel hack.")
There are two parameters for this module:
timeout_ms: Milliseconds to wait for a USB message to complete before timing out and returning an error. Default is 10.batch_output: Batch output messages with the next input request rather than sending them immediately. Since the multiplexer requires outputs to be sent when requesting input, this can increase performance when input is frequently polled anyway. Default is true (batching is on).
To compile the kernel module, run make inside the mod directory. This
should build a kernel object file piuio.ko against your currently installed
kernel. To install this module, place it in your distribution's directory for
kernel module updates. This often looks lomething like:
/lib/modules/your-kernel-version/extra
/lib/modules/your-kernel-version/updates
or similar.
Two tools are provided for testing I/O through this device. These tools are
found in the tools directory.
intest: Display input live from the I/O card.outtest: Read any of the characters [RLDUrldu1234B] from standard input and toggle the corresponding outputs. (Note that this will not happen immediately unless you turn thebatch_outputoption off.