Thanks and I apologize for the long delay in this update. Due to the feedback that I have received, I will not be continuing with this board. Thank you to both Larry and Kelly for all of their help. I will outline what happened;
Today I talked with Kelly and I am not sure what happened, but somehow his mainboard is now fried. He has his printer out being looked at and repaired and he should have it back later this week. The board he is using was thoroughly tested before it went out and was running on my printer for at least a month. I feel terrible. Kelly is going to send the board back to me when he gets the printer back from repair. I gather that he is doing a bunch of upgrades regardless, so the fried mainboard did him a favor. Here is the interaction via Facebook messenger between Kelly and myself.
I have reviewed the documentation and the pinouts and it all looks correct. I am at a loss on what went wrong. Going forward, I will look to make them more specific.
After Larry read the post and discussed this with me, he is not moving forward as well. We are cancelling the entire program. It turns out that the wiring and setup are a bit to complicated.
I can totally see how the cabling and the connector is a total pain in the back side. Steve and I are working on another design that does not have the screw connectors used during this implementation as well as some of the additional wiring requirements. More specifically, it is a hat for the PI that has a direct 24 pin Molex connector and powers the PI directly via the internal pins. The initial design is complete. It works with the PI 3 and PI Zero. Steve has built the first one and is going to be testing the hardware shortly. He and I went over and over the hardware design and all of the features. I am working on the software for Octoprint as well. It is a combination of the PSU and LED plugin for Octoprint, as well as some additional features. I will have a specific post regarding this and the design. I am expecting to have them here for testing the middle of November 2017. I believe strongly that this should be put out as an open source item, under the Creative-Commons Sharealike license. We are still discussing it.
While working on this note, there was a post by Ed Burchard about another ATX breakout board. Francesco Truzzi in 2014 created an interesting ATX breakout board. This is not exactly for 3D printers and Octoprint, but I just thought that it has a lot of great features.