Hacking a GVG (Grass Valley Group) 200 Production Video Switcher to work with an arduino

![GVG-200]({{ site.url }}/images/GVG-200-Overview.jpg)

I managed to get a GVG-200 Production Video switcher on ebay for cheap. Let's hack it to do fun things!

The main board is meant to communicate to the frame switcher (the bit that actually does the video switching). This commuinicates over a DB15 with something like 4 or 5 RS422 lines - not great to try and guess commands for. Instead, let's try the parallel bus that runs through all of the modules.

Doing some data sniffing from the couple of 7-segment displays that turned on rewarded pretty much nothing with a tiny burst of data appearing on some lines. Disconnecting these produced no different results on the displays so I tried a different route. I then traced all the traces coming off from the parrallel bus on the 'XPT Module' (the one with the most buttons). This gave me the following pinout:

  • I will fix this at some point (try copying into a text editor?)
Pin What Bus Pullup/Pulldown?
29 Bit0 Dout Float
12 Bit1 Dout Float
28 Bit2 Dout Float
11 Bit3 Dout Float
27 Bit4 Dout Float
10 Bit5 Dout Float
26 Bit6 Dout Float
9 Bit7 Dout Float
25 Bit0 Din 680K to GND
8 Bit1 Din 680K to GND
24 Bit2 Din 680K to GND
7 Bit3 Din 680K to GND
23 Bit4 Din 680K to GND
6 Bit5 Din 680K to GND
22 Bit6 Din 680K to GND
5 Bit7 Din 680K to GND
21 Bit0 Addr 680K to GND
4 Bit1 Addr 680K to GND
20 Bit2 Addr 680K to GND
3 Bit3 Addr 680K to GND
19 Bit4 Addr 680K to GND
2 Bit5 Addr 680K to GND
18 Bit6 Addr 680K to GND
1 Bit7 Addr 680K to GND
13 GND
14 GND
15 GND
16 GND
17 GND
31 NC
32 NC
30 ???
33 ???
34 ???