Latest OLED Watch (Isn't OLED)

The OLED watch project started when I saw some small OLED displays on ebay and thought 'What can I do with that?'. The watches followed, but there was always the problem of the power consumption of the display. I manage about 400 hours of use from a rechargeable 2032 battery, more from a non-rechargeable (the capacity is higher).
So, I had a look around and found a lower power display, one of the Sharp memory LCDs. These are very low power LCD displays.

A redesign of the hardware to drive the LCD was needed as the display isn't I2C, it's a serial bit stream. The hard part of using this LCD was finding a way to solder the 0.5mm pitch connector on to a PCB. Milling that connector was challenging as well. In the end I got a new soldering station so I have hot air. I also have a stencil for solder paste application. As well as milled PCBs I had a few made up by Dirty PCBs so I have a full solution if I need it.

The code was adjusted and the display was up and running.

The PCB is reversed due to the layout of the display connection. It's a cleaner look, but less interesting. I may revisit that in a later iteration.
The battery has also been reversed.

The overall watch is as thin as the OLED one and is very wearable.

So far the battery life seems to be far in excess of the OLED watch. The display update takes 20ms and to get power consumption to an absolute minimum the display is updated every 5 minutes. I'll see what real world battery life I get from this and then decide on what update rate I'll settle on.

Latest OLED Watches

The latest iterations of the OLED watch are finally approaching wearable. Well, the first of the two is wearable but a bit thick. The second is much more wearable size.

The first iteration is the smallest PCB so far fitted into a 3D printed case and mounted on a cloth strap latched with velcro.

The switches are mounted on the top and the clear front flexes when they are pressed.

The overall thickness is 15mm, which is a bit too thick to wear comfortably. It gets caught on sleeves and catches easily on fabric.


The latest iteration is a one that doesn't use a PCB. This removes 1.6mm of thickness immediately, but makes the construction more manual.

The wiring is manually laid out and not very tidy. the thickness is much less, at 9mm, or 10mm to the tops of the front cover screws. Compared to my main watch this is very similar.

The components are mounted in a 3D printed frame like this earlier version:

The minimum thickness is fixed by the switches that I have used. The wiring adds a millimetre or so to the thickness, that could be reduced by inlaying the wires into the frame. More use could also be made of the 3D space in the frame. At the moment there are no components on top of components.

Using a PLA 3D printed frame is useful as it is possible to heat components and wiring up with a soldering iron and push it into the PLA. This then holds the component firm when the plastic cools.

There may be a better way to wire the components, maybe using a smaller PCB that just has the surface mount components on it.