I thought I'd give an update on PicoGUS 2.0: boards are now in production at JLCPCB. I hope to get them by next week! Also, I have quotes out with some sheet metal bracket fabricators for a metal bracket for PicoGUS 2.0. That will raise the selling cost of PicoGUS 2.0 from $40 to $45, but I think a real metal bracket will be worth the cost. That does delay the release of PicoGUS 2.0 by 2-3 weeks, but again I think it will be worth it. It will also give me some more time to work on firmware improvements like USB joystick support and increasing the reliability of firmware flashing from DOS on some chipsets.
One thing I discovered when designing the new bracket is that the ISA card dimensions I've been using are wrong. I've been using the diagram in this well-researched blog article but it has an error: the distance from the center of ISA pad A1 to the card bracket face is too short by about 1mm. I'm now using the dimensions from the EISA spec, corroborated with caliper measurements from about 15 different ISA cards in my collection. If people have been finding that their PicoGUS cards with 3D printed brackets don't quit fit perfectly in their PCs, this wrong dimension is the reason why. I'll be releasing corrected STL files for the brackets soon.
Also, I am working on a prototype PicoGUS v1.2 design. The goal of it is to solve a few of the issues with the v1.1/v1.1.1 design and do things a bit differently to have a design that is as friendly for DIY assembly as v1, but also makes full PCBA production at places like JLCPCB possible. The changes are:
- Add pull down on RESET and RC on RUN, and specs 74AHC14 for U5 to prevent reset glitches
- For the DAC, you can either use the purple DAC module that previous versions use, or use the footprints for a PCM5100 and supporting circuitry directly on the board
- Uses 5V open collector on MIDI out to allow use of more commonly available resistors
- Uses 1206 SMT resistors instead of the two through-hole electrolytics
In a nutshell, PicoGUS v1.x will continue to be the DIY option, as PicoGUS v2.0 only really makes sense for fully automated assembly.
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