Jornada 720/8 hardware retrofit

Hi friends,

I see that most of us here have a fond appreciation for our 2 decades old little Jornadas. In fact, I would say that more than half of the conversations on this forum touches the Jornada in one way or another. I see Stefan doing a great job compiling a newer Linux kernel to run on the Jornada, but that hit a huge hardware wall that makes the project sluggish on the device.

With that being said, I would like to see if we could join forces as a community and create a retrofit kit for the Jornada. I thought about this subject many times in the past, but I always stumbled across the fact that I can't find a newer display that would fit the case properly. Most displays today are 16:9, where the Jornada is 8:3. Hitachi is the original manufacturer of the Jornada's display (Hitachi SX16H003). While checking again for compatible displays, I came across this "newer" Hitachi TX16D18VM2CAB display. It has exactly the same characteristics of the original Jornada display, exact same size, but instead of being a 640x240 CSTN display, it is a 800x300 TFT display! I know this is not the most advanced retina display ever, but it is a great enhancement over the original display.

The other part of the job would be to develop a new mainboard that can fit on the Jornada's case. I thought about the board being developed around the Pi Compute Module, as this is cheap, widely available and very well supported. The board will have to interface the new Hitachi display (need to check hardware interface and protocols, maybe requires writing a fb-based linux driver) and the original keyboard. For the keyboard, I assume it won't be too hard. It should be straightforward to decode the signals and then either convert it to USB HID using a microcontroller (Atmel has great chips for that), or write a kernel driver to interface the keyboard directly. The microcontroller could also be used to read the Jornada's glass digitizer and convert that to mouse coordinates as well.

Of course we also must think about power converters, recharging circuit, etc. But there isn't a lot of things to think about. If we have the compute module ready, the display, and the keyboard interface, that's enough to breathe new life into our little old gadget! I have some PCB design experience, plus low level coding as well. I can design the mainboard and write the keyboard driver. I will definitely need help with the display interface. What do you guys think about that? Anyone willing to contribute?

Edited by ntware 2020-10-02 5:04 PM

Uhh. I love this.
I had a similar idea before i upgraded the RAM boards. But due to lack of time i did not start this project!

I help wherever I can!

I did not read the datasheet of the module, but the Pi has a DPI interface with a wide variety of fb-drivers ...
The Keyboard part can be done with a teensy over the USB port! I have some schematics/software for a Jornada keyboard somewhere.
Charging and power should be no problem at all.
The only thing iam a little bit worried is the display cable, and space inside the Jornada!

Regards
Stefan

Certainly an interesting idea, and there are certainly a lot of options for getting PCBs printed cheaply these days. It'll need some 3D printing though, like a replacement module for the modem and PC Card slot to (say) a USB C-type or may be an ethernet port in the modem slot. Probably some new modern-cell batteries at this point too.
You'll need to re-write the notification LEDs in as well and have a break-out for the media controls, speakers and mic.

Presumably the CF would be retained but the PC Card slot dropped in favour of

I would be interested to know if a straight swap of the display was actually that easy, especially with the digitiser still working?

Did you find a shop that sells these displays? Everywhere i looked they are sold out / discontinued ...

I didn't look much. I would assume that getting this display would be hard. These Hitachi displays were meant for industrial applications (HMI-like). I'll keep looking and let you guys know if I find something interesting. The digitizer is not permanently coupled with the display, they are detachable. This means that we can get a totally different display and place it under the digitizer, and that will work just fine. If I'm not mistaken, Jornada's digitizer is a traditional 4-wire analog interface (X+,X-,Y+,Y-). It's easily readable from a uC like the teensy or anything else that has proper ADC inputs. Talking about that, I do love the Teensy platform, but it might be too juicy for the task. I was looking for something less power hungry, on the 8-bit spectrum, since all it is going to do is read the keyboard (and possibly the digitizer) and send some USB signals.

About integrations with other peripherals, I was thinking about starting with the basics first: mainboard with CPU and wifi (compute module), keyboard, display and digitizer. This is enough to have the machine operational. Once we have the first level ready, we can expand the main board by adding more components. USB ports can be added at the empty area on the right side, next to the phone jack input. It would just require a small cut in there to fit the USB connector. I planned on keeping the PCMCIA slot intact. Later on we could even try to design a bit-bang interface to talk to it from the compute module. Same for the CF card slot.

edit: I found the display here. And this is one of the suppliers. Apparently the same display is also sold under the brand KOE

Edited by ntware 2020-10-02 8:40 PM

I love this idea, I toyed with the idea myself with a broken J690 I briefly owned, but at that size at least it was well beyond my abilities. With your skillset it seems very doable though. I'd be more than happy to volunteer my 3D printing and mechanical design capabilities (such as they are) if you need any adaptors / case parts / port covers etc. for this project. I'll soon be taking delivery of a 2nd 3D printer, a resin one well suited to small precise parts. I'd imagine this part of the project is some way off yet though... As a side note I'm using a Teensy as a keyboard controller in one of my projects, I can hook my little USB power meter up to this while I'm using it and get some readings while it's running if that's likely to be useful to you.

Oh, that will be very useful Robert! Perhaps we can explore the power saving modes on the Teensy to see if we can go very low power on it. My only concern would be for it to reduce Jornada’s battery life, as this is one of its main features

Maybe try this place?
https://www.hkinventory.com/p/d/TX16D18VM2CAB.htm

It says it's in stock.

I don't have any coding or circuit board knowledge, but I can surely help with sourcing components both in Hong Kong and from mainland China.

I am used to buying things off taobao (the Chinese equivalent to eBay). Shipping is pretty fast and smooth and CHEAP (~usd$3-4 per KG!).

I don't actually believe in collective unconsciousness or synchronicity. But ... somehow this is really what I have been contemplating on since last month:



But the double USB connectors make it a bit too high for the slim casing. Perhaps I should go for Pi Zero then (dirt cheap over here locally, around usd$15 only!).

What motivated me to daydream about this project is videos like this one: https://www.youtube.com/watch?v=AKWheG8wKxM

I am also be happy with 3D printing stuff. I'm no experts but can use Cura and TinkerCad and print with 0.2mm extruder at 0.08 layer height with really good results.

Edited by hpcboy 2020-10-03 8:49 AM

I had a quick try at this today - Sadly I can't give any useful readings yet as the current draw from the Teensy is basically lost in the 'noise' on my cheap power meter - I also forgot that this one has a resolution of 10mA so probably not much use at microcontroller current levels. I've been looking for an excuse to buy a better power meter for a while though - One is now on its way (still a cheap one but with a higher resolution and with some averaging / storage functions so more useful for this and other jobs I have for it).

Pi Zero is not fast enough for desktop usage. Not to mention it is single core and very hard to get in quantities. That's why I though about the compute module. It is a bit more expensive, but can give you the performance of a Pi3+ with a 64-bit processor, multi core and integrated eMMC. Check the description here: https://www.raspberrypi.org/products/compute-module-3-plus/

My new power meter arrived today - It's vastly better than the old one. I was able to get some decent readings from the Teensy (acting as USB keyboard with my Eee PC keyboard), current draw was a very steady 26mA. With some very enthusiastic typing I managed to get it to go up by 1mA, but it doesn't drop below 26mA, no matter how long it is idle for. Clearly no power saving settings implemented at present. For reference an ordinary desktop USB keyboard drew about 20mA.

There is useful page here covering power saving with the Teensy - https://www.pjrc.com/teensy/low_power.html - Most promising without major mods seem to be dropping the clock speed and turning on idle mode.

ntware - Please let me know what would be most useful for me to look at first, for my own project I'm letting it turn off the USB ports when the system sleeps so haven't much looked into optimising power usage on peripherals.

I think the best way to approach this project is by, as we say in Portuguese, eating by the edges. That means that we must target each step individually. I think the first iteration would be to manufacture a new mainboard based on the compute module, that can interface the Hitachi SX16H003 display (this is the Jornada's original display), keyboard and touch digitizer. This is the bare minimum to have a powerful new Jornada running on the same case with the same peripherals. Later on, we can think about changing the display with a better one, adding USB ports, WiFi, Ethernet, etc. Definitely the most challenging this will be to interface the display. I have an old broken Jornada that I can use to start interfacing the display with a Raspberry Pi. I'll do my research here, anyone interested in helping will be very welcomed. _den-null I could definitely use your hand on this!

Just to follow up on my research, the most detailed website I could find with internal specs of the Jornada is this: http://www.jax184.com/projects/Jornada/Specs.html

There you can find datasheets for everything, but most importantly the Hitachi Display and the Epson Display Controller. We will need a display controller to be able to interface the Hitachi LCD panel, but I can't find anything on the internet about that. The panel is simply too old, and anything I can find about it directs me to buying the display. Perhaps our best bet is to reverse engineer how the Epson controller is connected to the LCD panel on the Jornada, and then use the Epson s1d13506 datasheet to figure out how we can interface the Epson controller with the Raspberry Pi. This means that we will have to use an ancient LCD controller to interface an ancient LCD panel. But that's ok, worst case scenario we can scavenger the parts from the Jornada's mainboard itself.

I've skimmed through the manual of S1D13506 Color LCD/CRT/TV Controller and it has the interfacing to SA-1100 (ARM) processor in the last part.

lots of timing and other technical details there.

Update: I found a Japanese site that interfaced S1D13506.

According to the site, parts like LPC2478, LPC1788, SH7262 can be used, which has LCDC to control the LCD.

Some details on this Japanese site.
http://elm-chan.org/junk/aki3k/report.html

I'll try to search around for info on the HITACHI LCD panel and will post it here if I find anything.

Edited by stingraze 2020-10-09 11:28 PM