I've decided to start on a digital-watch-project. It won't be very interactive, pretty much only "turn on, see the time and maybe temperature, humidity etc". It will use a small SSD1331 OLED display. To keep the time when it's turned off I thought about using a DS3231 AT24C32 IIC real time clock. For the temp & humidity (humidity isn't very important but would be cool) I don't really know what type of sensors to use.
I'm also confused on what type of Arduino I should use. Something small is obviously good and 3.3 V instead of 5 V is also good to keep battery consumption lower, but I still need enough pins.
When it comes to the battery I'm also not sure what voltage to get to power everything in the watch. All my other projects have had a powersupply plugged into the wall. Should one get a rechargable 3.7 V battery with x amount of mAh, or strive for some kind of battery holder so that I replace batteries instead of recharging one?
I respectfully think you should think the whole thing over again. Arduino really isn't for this sort of thing. By all means make a clock. It is possible to make a useful one that you can be proud of. On the other hand, I submit an Arduino watch would leave you looking like an idiot, and you will be a lot better off spending about a quarter of what you paid to make it, and walking out of the shop with a real one. If you really want to join this silly circus, I strongly suggest you make the case for it first.
I will share my project here. I tried to outline some of the many challenges that making a wrist watch entails. If you want something that is useful and looks good, then it is not a beginner project. By time all was said and done, I had spent several hundred dollars and over a year of time, but I learned a great deal. I'm still wearing this watch to this day!
Nick_Pyner:
I stand by what I said, but that is a truly heroic project.
It has just occurred to me that, these days, one is likely to 3D print the case - after designing it around the finished watch.....
I'm not disagreeing with you. I posted my experience to support your point of view. Making a watch sounds easy, but it is extremely challenging, and a beginner is not likely to understand that and become discouraged. I had to learn several new skills (smd soldering, library modification, sleep modes, interrupts, datasheets, pcb design, 3d design ect.) that are not immediately obvious to someone who wants to "make a watch". It is possible to make a watch as many people have with Arduino, but there's a reason why most of them are huge and ugly and don't have a long battery life.
That's why I didn't post the schematic or code for my watch. I've shared enough details that someone serious enough to learn can be inspired by it for their own project, but somebody who wants to "make a watch" and is still deciding on 3.3V, 3.7V or 5.V or asking which uC or display to use is not yet at the skill level to understand why I designed mine the way I did, or successfully build and troubleshoot such a project.
It would be a very good idea to start with a watch kit, as above.
Also start to build desktop or wall clocks, as there is a lot you can learn from that, too. The cost is extremely low, and they are mechanically easy to construct.
