After crashing my GoPro into the ground quite hard, I decided to use an enclosed case to protect the lens. This severely reduces the sound level on the internal microphone, so I decided to use an external one.
I bought a cheap cable from China, though the first one never arrived, and the second one didn’t work because they plainly used the wrong connector.
The GoPro accepts both regular USB Mini (for data and charging) and 10 pin USB Mini to add external microphone, and analog AV out.
USB Mini 10 pin, nearly identical to the 5 pin, until you look closely.
So I bought a 10 pin connector and soldered the microphone-end of the Chinese cable to it.
Round 1, no result. apparently, 100kOhm on the ID pin does *not* trigger the external microphone. After replacing this resistor with a 330k resistor (as suggested somewhere online), the external microphone works!
The finished microphone cable. Looks identical to the eBay listing, but this one actually works.
I’m quite pleased with the cable, its very compact, light and flexible. However, I wanted more. Two things that interested me were the option to charge the camera while in use, and the analog video out. I have a small 5″ display which I could use to look at what the camera is seeing in real time, as a kind of viewfinder.
So I soldered together a much more complete cable. The microphone input still works, but the analog video out does not. Maybe they cannot be used at the same time? Maybe that is the function enabled with 100k? Oh well..
The more-functions cable. Too bad the video out doesn’t work like expected.