Hi
I'm looking to build my own hand watch.
I posted here because I want to know suggestions on equipments I can swap to build a better and more efficient watch.
The idea I have by now after research is that a display like this Display, with a ESP12E behind it (with attention to code, to have low energy consumption) and a li-ion battery coin cell like LIR1620. The problem I went around is how to sync time. Wifi would consume too much power from the coin battery, it would be like 10x the maximum current it can withstand (when transmitting), also if it were possible via wifi, it would access my wifi generated by my mobile and get the info via the same server as windows does (EDIT: only to sync, then it would disable wifi and add the seconds). Ok, so I decided to add buttons to eliminate this wifi problem. I could pull a bit of the terminals from the display to make a flat side and add few "nano" switches like nodemcu esp8266 has for flash/reset buttons. So I'd do that by setting the GPIO pins (the ones for SDA, SCL, VCC and GND for the display) to input to read the buttons when the display is off. So then I could adjust time and one button makes the GPIOs turn into serial and power for the display (i.e., the turn-on button), so I can see the time I set. I'm very forwarded to not soldering too much because I don't have good soldering iron with proper tip for SMD. Also I don't feel like going to websites for custom PCB making.
Another thing to mention is that the display, ESP and coin battery would fit within 16 mm width. This width is not a requirement, it's rather a size I found slim. The length would be superimposed by the display. If wasn't clear, yes, I'd pile battery, ESP and display, from bottom to top.
Maybe if anyone of you have suggestions on libraries I should use, uC for low energy, another tiny display, a good fitting battery, I'd greatly appreciate.
Thanks in advance.

 

I'm very forwarded to not soldering too much because I don't have good soldering iron with proper tip for SMD. Also I don't feel like going to websites for custom PCB making.

That will make for a very challenging project then. Let us know how it goes.

 

Just found out there's this ESP32 with embedded colored display, with a sneaky battery connector. Just need to buy the battery separetely. But the good thing is that this YCE 402030 battery is 180 mAh, higher than the current miband (125 mAh). I can wrap it in a cloth to hold it all, just need to make something fancy. Also it has BTLE, which I can use with my knowledge of appinventor to upload notes and time. Seems I'm gonna have some fun.

 

If you want this to be a serious watch, with low power and accuracy, you need to move away from ESP-anything and get a small surface-mount micro using a 32,768Hz crystal and run a *LCD*.

 

If you want this to be a serious watch, with low power and accuracy, you need to move away from ESP-anything and get a small surface-mount micro using a 32,768Hz crystal and run a *LCD*.

I understand, but higher power can be sustained by larger battery or 6 days of on time instead of 7 days. I don't mind that day lost. Also, every week I'd disconnect the battery, so accuracy is not of a big deal, as it will shut down. When I upload time and date on turn on again, it's all okay again.
And this will be a one time project, not for sale.