I'm curious about the level of expertise you need in order to do this. I also have a cheap bracelet and I wanted to do the same thing, but reading this article seems like you need to be an expert in electronics/lowlevelprogramming.
Hi, author here. I can honestly say that I’m definitely not an expert. I tried to systematically write down questions on a text file and solve them one after the other. Solving one usually added a few other ones. “What chip is this?”, “how to program this chip?”, “do I need a development board?”, “what’s SWD?”, “how to pull an output high?” Etc. Lots of these are specific to this chip, too, so a lot of it is just reading the documentations and drilling down on libraries.
It’s something I find refreshing to read and like to state when I can: none of this was easy for me. But it was definitely fun. Having no deadlines helps. Having no practical goal and just enjoying the process was also refreshingly nice.
Hi author, nice hacking and writeup!. Nordic employee here. Note that if instead of the SoftDevice and the SDK you would've used Zephyr then you'd be able to do the same you did but with a fully open source software stack, including all layers of the BLE protocol stack. More here https://github.com/zephyrproject-rtos/zephyr
Hi. I use Jekyll and a Makefile that pushes the generated html to S3. I also needed to set up a cloudfront distribution instead of using a bare web-enable S3 bucket so I could use aws’s https certificate automation. Let me know if you need more details.
Some background helps, but there's nothing someone sufficiently determined couldn't do.
Recognising the I2C/TWI pins for example is a really quick win when looking at the OLED display. Otherwise, there's nothing much to do but spend a day googling - but you would find it with tenacity.
The difference in experience here is in turning it from a year long learning project for a beginner to "uncountable hours over several weeks" of exploration for someone a little more seasoned.
You need to have some experience, and the whole thing probably took a considerable amount of time, but basically it's not rocket science. It's a specific set of technical skills rather than stuff that's conceptually hard. Starting with a standard ARM dev kit like STM32F4 would give you most of the skills.
Electronics is a similar situation to programming: from the right perspective, it's quite easy: all of the details are very small and simple. The complexity is all to do with the way that many (MANY) small details are packaged together into a larger whole. Experience just helps you recognize common patterns, because you've seen them before. In theory, anyone with patience and determination can do this. The original article is well detailed for someone with knowledge of (or willingness to research) all the things called out, generally by name.
What I'm reading (I mostly skimmed the article) is that if you've connected an arduino with an OLED display, you should be pretty far along already. But, it does involve knowing how to read technical specifications. (as well as a steady hand, this stuff is tiny!)
I'm in the middle of a project using a related microcontroller (the nRF52832). When I started, I had very little electronics/embedded experience, and now I have more! It's absolutely doable.
