Show HN: Reversing a Cinema Camera's Peripherals Port

Summary

So recently (actually three months ago), I acquired a used Sony PXW-FS7. It’s very heavy but produces also produces very nice images, which is all I wanted of it. (This is what it looks like rigged-out, mine has less stuff. Pic from the internet) It has this weird if you’re not used to ENG cameras side grip for holding the camera when it’s on your shoulder and then controlling it in a pretty ergonomic way. My only real problem with it that some buttons can only be reached using this removable accessory. Particularly the user buttons 4–6 (if you know old Sony menu systems you know the need for shortcut buttons.) This becomes evident when not shooting from the shoulder but e.g. the hip. You hold it from the top handle and can’t reach the buttons I use for focus zooming which is essential when using a camera that has zero usable auto focus (with a manual lens lol). I thought a bit and came to the conclusion that since it’s a tool used in an industry that kind of expects expandability and modularity (to a degree, but think of RED’s business model for example) and that the camera is already over 10 years old it would not be an extraordinarily complex/secure protocol the camera uses to communicate with the electronics in the grip. And so, without ever having attempted anything resembling this complexity and only knowing how an oscilloscope worked in theory, I made it my mission to reverse engineer the protocol and develop my own hardware to have another set of buttons on the top handle (or wherever to be honest.) I had 23n27 who randomly was also at chaosdorf at that there holding my hand a little so we quickly figured out it was a serial protocol looking veeeery similar to UART at 9600 baud. Of course we only had one wire which was a bit weird to me at first but that just means it’s an open-drain bus. The camera wiggles the voltage for a “placeholder” of sorts for eight bytes of all zeroes and whenever it’s low, the grip can pull it high. This is very visible when pushin...