The Universal USB8255 IOIB

As you can see in the project block diagram above, the central of the project board is the Universal IO Interface Board. This board can be linked both by USB Black Box and Futurelec ET-8255PCI. As such it is very important to fabricate the board so that either of the programs from USB or PCI can be tested via it.

This is the basic Input Pins Configuration for the three main input to and output from this Universal Interface Board. I call it CN-A, CN-B, CN-C. CN-B is a 40P IDC male connector coming from USB Black Box. CN-C is a 34P IDC male connector coming from Futurelec ET8255PCI. Actually there are 3 outputs from Futurelec plus another relay contact NC & NO. However, I just prepare one for this UIB since for the time being there is no specific big project that requires 72 IO at one time. Yet another, if for testing purposes, the other two can use the same one connection by exchanging the connectors only. CN-C is the output 40P IDC to the existed 8255 IO Interface Board.

This is how the basic wiring for the Universal looks like.
Actually the main reason why I designed this UIB in such a way is simply because the 8255 IO Interface Board is already tested and worked nicely with the previous ISA 8255 IO board. Since that old board is no longer available and now we have both the USB and PCI 8255 based interface boards, so I guess it is wise to use the proven working inrface board. While it saving development time it also cut the research cost. Yet another, both USB and PCI are based on the same IC's which is 8255. However, since both of them are from different companies, so the ports of addresses and communication would be a bit different. What more, USB and PCI would give some opportunity for us to learn new knowhow or knowledge of how to program the hardwares as previously we only worked with ISA. The most important, this time we will within Windows environment, rather than DOS. This is also another experience of a lifetime.