Raspberry PI TFT Display via DPI-GPIO Interface

[homebrew]

Hi everyone,

just wanted to show a (small) success I had today with a salvaged display from an old (ca. 2010) HP Pro 8600 Premium Inkjet printer.

Apparently it is an A043FW05 - pinouts can be found via google.
This particular display works without any alterations with the Adafruit config files found here: https://learn.adafruit.com/adafruit-dpi-display-kippah-ttl-tft/installation for their 4.3" setup.

So ... lessons learned:
1) Don't throw away old display's of any sort - chanced are good that they can be reused.
2) Don't be afraid of hand soldering a 45-pin 0.5mm pitch connector - with a normal soldering iron and a microscope it is well doable.

I used mylar-tape to insulate the connector against the pads of the perfboard and to temporarily hold the wires in place. For extra mechanical some epoxy secured the connections more permanently.

Not quite elm-chan level soldering but apparently good enough ...

Currently an external PSU powers the backlight as it requires some 20 mA at 26V minimum for the LEDs. I'll probably also salvage the inverter from the original printer pcb.

Feedback and comments welcome

[Bud]

Great hack, true spirit of an electronics enthusiast!! 

[Scrts]

That's nice! What's the frame rate?

[Old Printer]

Excellent work. I have read so much about not bothering with undocumented displays. This is a tinkerers dream, got to have time to kill. Retirement is coming. So many communities are hosting electronics recycling, mine does it once a month. I have not approached them yet, but they farm out that part to someone local. A guy just sits there Saturday mornings collecting piles of discards. Next time I am down there I will ask about picking the odd piece or two off the pile.

[homebrew]

That's nice! What's the frame rate?

Thank you! According to the settings it should run at 60Hz. However, I'll measure this ...

[homebrew]

I have read so much about not bothering with undocumented displays.

I would double that - if it really is completely undocumented it would be quite a challenge. At least I got the chance to find a pinout - and a datasheet. However, the process was not straight forward and took me some hours of googleing various parts of the seemingly random numbers printed on the display casing. What really helped me was the flex pcb connector itself. You know the pin count, where ground is attached to and in my case (though not used) I could clearly spot where the touchpad traces were routed through. That helped a lot dismissing some datasheets right away. 

But perhaps I was just very lucky ...

[james_s]

It's always really cool to get something like this working. It's harder for me to justify anymore though when I can buy a brand new display on a breakout board for just a few dollars.