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Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-10-11, 09:13

Received the sample ESS sound chips and ZIF socket finally. Still working on a super simple ISA mockup so I can test the individual chips before soldering but I should be ordering the boards soon. 🎧🤘🤘 Filename ES1869F.jpg File size 393.66 KiB Views 70 views File license CC-BY-4.0 Filename ES1869F_ …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-10-07, 07:18

Technically yes but only if I move the mounting hole on that side, or make the board longer. Neither of which I want to do. The mounting holes were a decision for practicality. The holes on that side align with the ATX mount for a full-sized motherboard in case someone wants to mount this in …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-10-07, 06:29

Okay, only a little hair-pulling, but I was able to "find" some board space for the ES1869F! 😅 I moved all the POST logic to the top. While the flip-flop was involved in showing system activity on the 7-seg decimals, I've chosen not to include that. This way the chip that has the flip-flops can stay …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-10-04, 21:24

You did say the goal was for either card to work in either slot, so if you delete one, the space increases. The two slots are for flexibility. Depending on what SBC and how wide it is, you can position things to fit better. For instance, I had an arrangement that worked better with the SBC in slot …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-10-04, 12:17

How about moving the post card chips in front of the pci and leaving the displays where they are? Well... It's not impossible. I've been staring at this for a bit and I may need to scrape this layout. I might need about 10mm more space to add some proper coupling caps to the audio signal path which …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-10-03, 21:29

Lol ok. Could you squish it a bit? Maybe put a few chips on the back or in front of the pci slots? Sound cards need low noise Yes, I'm aware the sound card needs a quiet spot, but specifically the anolog signals need a quiet spot. The choice to put the chip on the bottom left seemed reasonable as …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-10-03, 11:47

Made some headway on the layout. Things are getting SUPER tight! Waiting for the sample ES1869F chips and the test fixture. This is a list of features I wanted. Wavetable header: This will have to be a backward vertical mount because of the lack of PCB space. This should allow the smaller wavetable …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-09-29, 10:30

China and fraud. Name a more iconic duo Actually, the ones I bought from China were good... The ones from South El Monte, California were bad. Oh, well I guess. Ah, will look at CMI8330. I have a few cards with the ES1869F and I'm routing things for that. Hopfully the samples I ordered will work …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-09-29, 09:03

Signal too fast? So, the chips are all the same part numbers. (DM9368N). I built a quick test circuit and I can confirm the first two chips I got are bad! Now it's weird that the chip is current limiting like it should, so I guess it's some kind of LED driver, but I'm not sure what's going on. The …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-09-29, 05:44

Are you sure the 88s aren't upside down? One has a dot, the other doesn't. If one is upside down it might explain ir The decimals on the 7-segs show activity on the bus and bounce back and forth. They are independent of the DM9368N drivers. I double-checked a few times with the other chips to make …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-09-28, 13:52

Finally got some time to assemble one of the boards! The first test was 90% successful with all the major functions working. This is good news as it confirmed my assumptions about the reverse engineering of the Rockwell backplane. What works: The SBC slots work beautifully! This includes the PISA …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Prototype)

Posted on 2024-09-25, 23:43

Haha it's hard not to think further ahead. I've... Well, I started and then realised how much work it would be in kicad... To design a 7 slot wide backplane for modern pcie. Basically it would be Intel's project Christine but with the expectation that the sbc would face "up" in a tower case. Allow …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Design)

Posted on 2024-09-25, 12:27

It's rather strange. It's almost like Allen Bradley/Rockwell used "most" of the PISA pinout. They crafted their SBC, (at least the ones using the EISA slots), to inject the CPU 3.3V into the card from the slot instead of including it on the SBC PCB itself. As you can see, the Rockwell backplane has …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Design)

Posted on 2024-09-25, 12:11

Maybe I misunderstood it, but what are the differences between the sbc slots? One is one pinout standard and one is another? No. My goal was to craft the backplane so any of the different types could work in either slot. However, a full understanding of the configuration is important. Specifically, …

Re: Project "Backwards". A universal backplane for PISA, Allen Bradley, and ISA "half-size" SBCs. (Status: Design)

Posted on 2024-09-25, 12:04

Very interesting. I've sometimes wondered why, especially in the era of 50kg gpus, we don't move back to backplanes. In my mind, having the CPU card and gpu card mounted back-to-back vertically, would be the next logical SFF and maybe more step. Most people only use one card now. On that note, I'm …

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