Fruit Machine VFD
So after it arrived it was time to start the reverce engineering proccess. It turned out the VFD tube used has buiklt in driver chips that turned out to be shift registers.
The nice thing about this unit conpauired to the more common version is the driver electronics are not sandwitched between the VFD & the PCB, but are open for probing on the back.
After a lot of trial & error with the rig below I was able to generate a truth table of the bytes that yiou had to send to the display to get the charators & commands to control the display. All the info I found online about this truth table was wrong. So i made mine from scratch.
The pinout just took some time to figure out but was not to hard. Info I found online also confirmed I had done it right, some of the info online was wrong though. But this is why yiou do your own research. With that I was abole to put together the rig below.
The reverce engineering setup for figureing out the "protocol", even though I figured it out I don't know what the protocol is. Just a standard Pro Micro hooked into the serial input of the machine. I also traced out where the pins went on the PCB as well as the programming connector. The layout & design of this board was a little strange.
Ether way it worked for testing & figuring out the charator set of the display.
After lot of probing & experimenting sending random bytes at the display I was able to get it to display a question mark. Then I was able to get it to fill the display with the @ symble. Evententialy I was able to get the display to say "HI" repetedly on the display. This was a success as I was able to get the display to show something which is always a win on such projects as this.
After a while I was able to control what the display would show as I figured out how to dump the bytes to the dispaly.
One of the first tests getting the display to show THE_EPROM9. It worked a treat.
A more refined version of the THE_EPROM9 display scetch running with an animation that makes it scroll on the screen.
So after the success reverce engineering the first display I ordered to more. Both displays use the same VFD tube.
The "Reflex Gaming" display workjed with my code, anoyingly the other display did not work with my code & to this day I have not coded for this display. It uses a diffrent microcontroler.
All the other displays I have obtained use the same microcontroler. An Atmel ATMEGA8515. Turns out to be a pretty standard chip that you can pull the original code from if one so pleases. You could also use it as an interface point for your own microcontroler so you don't have to built the interface hardware for the VFD tube its self.
The display is a Itron MN09608A VFD. There were a few varyents used but they were esentaly all the same displays.
Due to the trace patten you can kind of make out where the driver chip is inside the VFD tube.
Acotone was used to removed the toner that protected the traces on the copper clad board.
PCB dureing asotone cleaning proccess.
PCB pre drilling after ecthing & cleaning proccess was complete.
The custom board all soldered up to the Arduino & display all working. First test after building.
The front after asembaling.
The back after asembaling.
Top view of the display doing its thing. Size was not a thing I really cared about dureing the build.
So it worked so well I made a second display, I programed it with my partners username & gve it to him.
My finnished display in all its glory. Showing my internet user handle.