A relative just bought a biofeedback accessory for an iphone 5/6 and was wondering if they could use it on one of my old iphones. She'd rather use an iphone without any data on it so people could use it without supervision, but the most recent one I have is a 4 (maybe a 4s, not sure).
I found this, but I'm worried it won't work. I know the best way is to just try it, and I probably will because it's cheap, but I'm interested in learning a bit about the differences between the two types of cables. Would a device built for the iphone 5/6 use a slightly different protocol? I see lots of adapters that allow new iphones to use old iphone accessories, but not the other way around. I assume a lot of that is just because there isn't a demand, but could there be a difference that results in only some accessories working in that direction?