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