Hi all. This is a weird project and not one I'm really qualified to handle, but ah well. Not sure if it's in the scope of Arduino as I'm not too well researched on it.
About me: No experience in electronics other than cursory knowledge. Lots of experience in high level programming, but very little with direct hardware access. My main concern is with hardware, as I will usually pick up software implementation pretty quickly.
LANC is a protocol in camera circles, which allows control of a camera via remote. The physical connection is a 2.5mm TRS-style jack. It also allows the camera to send back information to the remote control (such as recording status).
Tally is another protocol which essentially allows a light to come on when a camera is active. It's used in live broadcast situations - when a camera is on the air, the light comes on.
However, I do not work in live broadcast, but in video recording, so I don't use production switchers or anything else which can activate the Tally light on my monitor, but I do need the tally light to see when the camera is recording.
My idea is this: 1. Press record button LANC remote. 2. Start/stop record command is sent to the Arduino board. 3. Arduino does nothing with the command but sends it onwards to the camera. 4. Camera changes status from "not recording" to "recording" (or vice versa). It sends this status via LANC to the Arduino. 5. Arduino receives the status change. It passes it back to the LANC remote, but it also sends a signal to the monitor over Tally, reporting that the camera is "on the air".
Hardware is where I really struggle. I don't trust myself to solder (I've set myself on fire making a sandwich), but ah well, cross that bridge when I get to it.
Here is the spec for the LANC protocol: http://www.boehmel.de/lanc.htm Easy enough to follow, kind of. I'm not sure exactly what combination of codes I have to send to the camera to start recording, but if I can just receive the signal from the LANC remote and just pass it on, then that'll be fine.
From what I can tell, I only want to send a signal over Tally if the camera is reporting status "rec", so Byte 4, 0x04.
The tally monitor I'm using is a Blackmagic SmartView Duo which has 2 monitors and one serial port to control the tally indicators on both monitors. I am only concerned with "Monitor 1 Blue".
The diagram of the tally connector is here: http://i.imgur.com/dgZVxt4.png
I am unsure if Tally is standardised so I'm really not sure what signal to send it or what a contact closure is.
"Ports" I will need on the circuit board are "LANC In", "LANC Out" and "Tally Out".
If anyone can help me out with this, it would be hugely appreciated. I need to know everything. What would be the best board to buy, what cables to buy etc.
In the meantime I'm just going to buy a LANC remote with a status LED, but I really want to be able to use a tally light and this seems a good project to get into electronics programming.
Thank you so much guys, hopefully I'll soon be able to return the favour.