Investigate using a RaSCSI board as a pi-parport device

[quorten]

Investigate writing a Device Tree Overlay and building a DB25 rewiring dongle to allow using the RaSCSI board as a pi-parport parallel port interface.

https://github.com/akuker/RASCSI

Though it's a hack, passive SCSI bus termination (resistor-based) could be just good enough to get reliable communications with parallel port devices. Or it might require crude modifications to get sufficient termination behavior.

This could also address issue #4 since RaSCSI uses sequential BCM GPIO ordering for the data signals and (to the extent it matters) the control and status signals.

[quorten]

The interesting thing about the RaSCSI project is that it is very similar to the v1 design of pi-parport. Personally I plan on using the RaSCSI board as a SCSI hard drive and I'll see if I can make it double as parallel port interface.

[quorten]

We should have considered ourselves foolish not to realize this...

On pi-parport, if we connect A13, Y13, PERI_IN, and PERI_OUT rather than grounding the input and not using the output, api-parport board is also capable of being used as a RaSCSI board. However, you can only use it as exclusively an initiator or a target at a time, changing roles requires switching a DB25 rewiring dongle.