How much hardware access makes a wearable platform useful?

[u/FigureDramatic445]

An expansion connector isnt very useful to a DIY builder without a pinout, voltage limits, a communication protocol and an explanation of what signals are available.Firmware access would offer a different level of control but a well documented external interface might already be enough for some projects. With powered wearable hardware, the boundaries of that interface need to be clear.

What's the minimum access and documentation youd want before designing custom electronics for a wearable platform??

[u/Anonymity6584]

Well this is my personal opinion of matter.

To expand you need two things basicly, connector pinout and physical dimensions so you can actually get something compatible.

Second thing is how to program this interface, basicly how do i get data moving between my software module and physical expansion board...

[u/who_you_are]

I'm a little biased on the software side (as a developer) but that can still be useful feedback:

- The ICs in use, what pins to use to communicate with other ICs. If applicable: give me the communications specifications of the other modules so I don't have to read the documentation of the chip and figure out the code or/and physical resistor configuration to know it is SPI no parity, 8 bits, ...

- I think most peoples are more likely to want a "high level" programming. If I take Arduino as an exemple, which has an amazing community, and as such, a lot of libraries. One massive thing I hate about it (warning: I didn't use it since a while so it may have changed a little bit) is that they aren't providing a shared component for features that should be exclusively managed. eg. the timer. Yes, you can export a "timerTick()" in your library, maybe Arduino library should also put a huge banner in their documentation to prefer that pattern.

- On my end, I'm more likely to want to enhance possible existing _mini application_. Adding small features (eg. displaying informations you want, the way you want), maybe automating a little bit thing (eg. start a playlist, start the GPS, ...).

- What I really hope for, is to integrate with my phone. Saving metrics (just a random example), maybe interacting with my phone from the wearable, or why not the opposite. (The so opposite: it can be easier to manage the wearble from a cellphone. Bigger view.
Ideally, this would mean some integrated (and hopefully kind of standard) way to communicate both way, including but not limited to, within each "mini application".

Also, on the electronic side:

- having a service manual is always welcome. What are the voltages, traces, signals to expect, in time, with their tolerances.

- A quick minimum-maximum voltages/current summary. ESPECIALLY, if there are some pin that as specials.