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A project log for Psioπ

Resurrecting a Psion Series 5 PDA with modern innards

RasmusBRasmusB 04/25/2015 at 15:254 Comments

tl;dr - No progress as of last time. I'm considering another display model, and I'm hoping to assemble the final USB keyboard driver soon.

No, neither me or my project are dead, but there hasn't been much happening for a while, mainly because of work.

One setback is that the OLED screen I ordered was cancelled, and then the seller doubled the price when I wanted to re-order it. I'm not eager to spend $100+ on a screen which I'm not sure how to control yet, so I'm looking for other options.

I want to use an OLED screen for two main reasons:

  1. They are thinner and thus easier to integrate in my build. It may sound stupid when you know that I have around 4.5mm of depth to use in the lid, but you quickly run out of space when considering that I also need to fit a screen carrier, an adapter PCB and all the connectors. Every mm matters!
  2. It can be more power efficient than an LCD when showing dark content. Since I want to use my Psion mainly for text-based work, it will probably make a difference.

One of the projects I'm following could be a way forward. The latest project log from the DSI display shield project shows that they have gotten another display working. This is very similar to the OLED display I was considering but with higher resolution. This display can be had for around $50 from Asian retailers. The issue remains how to create the high-speed serial interface to drive a modern cellphone screen. The DSI shield project obviously has a working solution (HDMI -> DSI), and I could use that for prototyping. It would consume a lot of power though, and is not suitable for the final design.

There are adapter IC:s that can handle an 24-bit RGB parallel input signal (for example the Solomon Systech SSD2828), but I'd rather find a way to drive it that doesn't involve adapters to keep cost and power consumption down. The Raspberry Pi has had a DSI interface since the beginning, but for some reason the Raspberry Foundation hasn't made the interface available to users. It has been over a year since they showed a working prototype, but there has been no official updates since. The rumor mill has an official launch slated for Q2 2015... fingers crossed! :)

I have also done some more thinking about the USB keyboard I made. I haven't assembled the final prototype yet but it will happen eventually, mostly because I want to learn more about the USB-enabled AVR devices. But I did rethink using USB for the final design, because of the power consumption. It is more power efficient to get a dedicated IC to perform the keyboard functions, so I'll look into that after completing my USB prototype.

Discussions

Andy wrote 05/12/2015 at 20:38 point

Good to hear from you again! I myself have been a bit busy with graduating as well these days and I have not really been working on this project either. Similarly, I tried looking at the Mangascreen, but that appears to have been delayed as well. I hope some changes are at foot so that I can continue. In the meantime I am just playing around with FreeCAD to see how to accommodate with the limited space inside the Psion.

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RasmusB wrote 05/13/2015 at 08:05 point

Thanks, and good luck with the graduation! I'm ordering the components for the USB keyboard soon, so I'll expect to do a write-up on that soon (next month probably). Do you have a project log somewhere?

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Andy wrote 05/25/2015 at 15:39 point

Nope, not yet, I should start one. Do you happen to know what kind of material the outer casing is made of? I accidentally snapped one of the clips off and I want to glue it back. I saw somewhere that they mentioned the case was made of ABS, which would make ABS cement the most optimal adhesive.

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RasmusB wrote 05/25/2015 at 18:34 point

Yes, it is ABS. Let me know if you find a good adhesive. I'm going to have to fix some minor cracks on my units as well.

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