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Verifone 13817 4 Line VFD (Read 1286 times)
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Verifone 13817 4 Line VFD
Mar 19th, 2020, 6:29pm
 
Trying to hack the 4 line VFD from a Verifone "Ruby" Gas Station management/POS terminal (Pictured Below)
 
These displays are starting to appear on the surplus market.  (Note copyright date shown on display.)
 

 
The unit has only a 10 pin IDC connector.  There is no separate power connector, and there are no helpful markings or other clues like test points.
 
Here is a diagram of what I know about the connector at this time:
 

 
Pin one is marked with a square land on the PCB, and should be the red stripe if you have an appropriate cable.
 
Power is 5VDC, and a full display will need over 1 amp (1A).  A blank, idle display is about 0.4A.
 
WARNING: VFD (Vacuum Fluorescent Displays) Operate on HIGH VOLTAGE. There is a step-up circuit that boosts the 5 volts. Touching the Pins Leading to the Glass Tube (or other points) can lead to an Electric Shock even if nothing is displayed.
 
Unfortunately, unlike the Noritake VFD's described here, these displays do not seem to use a simple serial interface.
 
Momentarily holding pin 1 high seem to put them in a self-test or demo mode, but that is all I have been able to make them do.  It could be some sort of I2C or similar protocol that without help from the designer would be very difficult to determine.
 
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Re: Verifone 13817 4 Line VFD
Reply #1 - Apr 10th, 2020, 7:55am
 
So thanks to the current world situation, I have had some time to continue trying to make this very nice display do something useful.
 
So, looking at the pin-out (previous post), we see that there are 3 inputs, and 1 output.  I (rhetorically) wondered if there were any common interfaces that used 4 wires where the peripheral device would have 3 inputs and 1 output....
 
Turns out there is -- SPI:
 

 
 
So I connected up an Arduino Nano, and after a little trial-and-error, I came up with the following assumed pinout:
 
Code:
Arduino          Verifone 

D10 -->   *SS   -->   4
D11 -->   MOSI  -->   2
D12 <--   MISO  <--   5
D13 -->   SCK   -->   3
 


 
I then wrote a simple "Bit Banger" or "Fuzzer" to send random stuff to the SPI port.
 
Using this, with the above pinout, I do get data coming back on MISO, and things such as clearing the above pictured test mode, and in a few rare cases, I have gotten a couple random characters on the screen.
 
SPI has various possible clock edge triggering modes, as shown in the table below.  I seem to get the most consistent data responses in SPI_MODE1.
 
Code:
Mode	      CPOL   CPHA     Output Edge  Data Capture
SPI_MODE0	0	0	Falling	   Rising
SPI_MODE1	0	1	Rising	   Falling  <----
SPI_MODE2	1	0	Rising	   Falling
SPI_MODE3	1	1	Falling	   Rising 


 
Next, I need to write another Arduino program to allow me to replay interesting sequences of data or strings.
 
I do want to note that this display is *far* more complex than the basic Noritake serial units.  This display contains a Motorola 68000 processor, RAM, and 2 ASIC's.  It is likely quite capable, but with no starting clues at all, determining the full capabilities and possible modes of this device is likely to be a very lengthy process.
 
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