wristwatches that invite development

[NeverDie]

Color is an option for the one based on the ESP32, whereas the one based on the ESP8266 appears to be black and white only:
https://usa.banggood.com/OLEDTFT-Color-DevKit-ESP32-Watch-Development-Board-p-1561754.html?gmcCountry=US&currency=USD&createTmp=1&utm_source=googleshopping&utm_medium=cpc_bgcs&utm_content=frank&utm_campaign=pla-usg-rm-all-purchase-pc&gclid=Cj0KCQiAvc_xBRCYARIsAC5QT9l3MdPk8E0hMqlxHXnlmPz9j2RK8yc1NAogFB4TZtZrxgUGvvOA4KAaAuzFEALw_wcB&ID=6157240&cur_warehouse=CN

It would be nice if when you get near a screenless device your watch would light up with the information that would have been displayed if it did have a screen. That would save from feeling the need to put a screen on each individual device.

[alowhum]

Honest question: are devices that 'open' allowed to be sold?

[monte]

@alowhum yes?

[NeverDie]

@alowhum I'd say definitely yes. I'd wager that nearly all devices you own that you purchased can be opened, including RF devices, if by "open" you mean unscrewed. If, on the other hand, being open is a normal part of the devices operation, then it would have to pass FCC (or whatever it is for the country in question) in that configuration too before it gets the stamp.

Is that what you mean by "open"?

[Nca78]

@NeverDie said in wristwatches that invite development:

ESP32, ESP8266 appears to be black and white only:

ESPs are not a decent option for smartwatches. They are only an easy solution because they are relatively easy to implement compared to a low power bluetooth chip, and their high speed make things like interfacing a color lcd (for ESP32, ESP8266 is lacking IOs) easy also even if the code is not optimized.
But you want a smartwatch to survive more than a day, to be of reasonable size, and to interact in real time or seemingly in real time with your phone and as you would like here, with other smarthome devices. Not possible with wifi, keeping it enabled is eating way too much energy. And bluetooth on ESP32 is pretty bad also in term of energy use...

[NeverDie]

@Nca78 I agree with you, and yet there are companies making Arduino IDE friendly displays with esp8266 nicely integrated into them:

https://www.digikey.com/product-detail/en/4d-systems-pty-ltd/IOD-09TH/1613-1394-ND/7914219

https://www.digikey.com/product-detail/en/4d-systems-pty-ltd/SK-GEN4-IOD-24T/1613-1382-ND/7360955

They sure look as though they are meant to be used in watches. Maybe they serve some other purpose?

But, going back to the topic of better power utilization, I was looking recently at some of the STM32L low power MCU's, and some of them even include not only TFT LCD drivers but even hardware graphic accelerators:

https://www.st.com/content/st_com/en/products/microcontrollers-microprocessors/stm32-32-bit-arm-cortex-mcus/stm32-ultra-low-power-mcus/stm32l4-plus-series.html

But, unfortunately, they are lacking wireless. They do have wireless MCU's (a bluetooth one and a LoRa one), but both of those are lacking built-in LCD drivers.

I guess (?) with those you would drive the LCD screen in the same way as the Internet of Displays modules (above) are driven by the esp8266.

Of note, ST does say these radio modules were "developed using the same technology as the one implemented in our ultra-low-power STM32L4 microcontrollers:
https://www.st.com/content/st_com/en/products/microcontrollers-microprocessors/stm32-32-bit-arm-cortex-mcus/stm32-wireless-mcus/stm32wl-series.html

I don't know much about driving displays, but this guy managed to make a fairly compact watch with what looks like a decent black & white display using just an atmega328p as the mcu:
https://blog.zakkemble.net/diy-digital-wristwatch/comment-page-2/

A fancy smart-watch is a good touchstone/challenge. If you can make a wireless one that's of reasonable size for a watch and run for a good length of time on whatever power you can squeeze into it, then you can probably do just about anything IoT pretty well.

Maybe it's not as hard as it looks. A fairly cheap display for watches appears to have a hw interface already built in:
https://www.ebay.com/itm/KEYESTUDIO-2-2-inch-Circular-Round-TFT-LCD-Display-Module-for-Arduino-Watch-/133122982326

[NeverDie]

Hmm... Looking into it a bit more, there appear to be a ton of these esp32 display driver boards out there. Some drive e-paper displays and have LoRa on them as well:
https://github.com/Xinyuan-LilyGO/T5-Ink-Screen-Series

TTGO even has a watch series with built in LoRa:
https://www.aliexpress.com/item/33038999162.html?spm=a2g0o.detail.1000023.12.62c253deBh1jg2

Looking at the esp32 datasheet:
https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf
it says that in deep sleep with RTC timer and 8k of RTC memory retained, it's 10ua current drain. Meh, that may not be awesome, but I wouldn't call it terrible given that they're using a 700mah rechargeable battery.

[Yveaux]

@NeverDie This looks quite hackable: http://aliexpress.com/item/4000527495064.html
Not sure about battery life...

[NeverDie]

I was looking into possibly using an e-ink display, but then I read "Frequent continuous refresh will cause irreparable damage to E-Ink. It is recommended that the refresh interval be greater than 180s." http://wiki.seeedstudio.com/Grove-Triple_Color_E-Ink_Display_1_54/

If true, then it's obviously a non-starter for a watch.

I guess the Sharp memory display is the only alternative for an ultra low power display similar to e-ink ? I read that it was the display used in Pebble.

Maybe papercast is another one. It claims it can be updated at 7.5fps. [Edit: nope. Papercast only sells large displays that are too big for a watch].

[monte]

Not exactly a smart watch, but related to them. I've bought some round displays some time ago. This B&W: https://www.aliexpress.com/item/4000048389598.html
and this color ones: https://www.aliexpress.com/item/1904222704.html
Would recommend black and white ones, me and olikraus made them work with u8g2 library. It has pretty low power consumption with backlight off.
The color ones are bigger, have higher resolution and color(!). They have only parallel interface, but that's even good, because this way they doesn't have a bottleneck in form of SPI. They work with MCUFRIEND_kbv library after some edits.
So my first thought when I made those displays work was to make opensource smart watch...and then I read about Pine Time :)

[NeverDie]

After looking into it further, there may be no way to beat a reflective LCD for telling time, given the number of updates required:

So, I propose that an ideal smart watch would have reflective LCD for the frequently changing time component (minutes and seconds) and a Sharp memory display for everything else.

So, probably the easiest thing would be to keep your regular watch and then have smart-watch functionality on your opposite wrist (or wherever is convenient) that does everything but constantly display the time. That simplifies everything.

If there were some kind of micro sized digital watch LCD module that you could simply "drop in" to fill the role of constant time display, then you could combine the two into one, and maybe that would be the ideal arrangement. Here I'm thinking about something like the tiny digital time display in combo digital/analog watches, but without the analog part.

Rdot looks interesting, and they claim to be much more energy efficient than epaper (see above), but I don't see where to buy any of their stuff except for their $200 demo kit that they sell from Sweden.

Many years ago I used to have electrochromic night lights and backpacks lit by electrochromic tape, but this looks to be different than that. The very thin film nature of it would lend itself well to a wristwatch, though, since there's opractically no depth to it.
https://www.youtube.com/watch?v=BhC3NsWenRw

I just don't know where to buy digits made out of it. Anyone know of a source? Apparently they can be printed even by inkjet.

[monte]

@NeverDie the b&w screen I told about consumes 30uA without backlight. What are exact requirements for this type of watches?

[NeverDie]

@monte Not sure. I was looking at it from the angle of how to use as little power as possible. That way I learn something that I can maybe apply to other projects too. I don't really need a watch, so that part is just gravy.

[NeverDie]

A possibility would be to get a waterproof shell, such as:
https://www.aliexpress.com/item/32983519082.html?spm=a2g0o.cart.0.0.144f3c00YcDlHq&mp=1
and then craft your own DIY PCB with battery and display to fit inside it. If you put your buttons in the same place as the corresponding apple watch that the case is meant for, then presumably it would work. And it would be waterproof!

[Mishka]

@monte Charging it once a month might be a nice number to start from.

[Jon Raymond]

@NeverDie said in wristwatches that invite development:

craft your own DIY PCB with battery and display to fit inside it. If you put your buttons in the same place as the corresponding apple watch that the case is meant for, then presumably it would work. And it would be waterproof!

So like this or this? Even has full open source Arduino firmware. Really an impressive project!

[NeverDie]

@Jon-Raymond said in wristwatches that invite development:

So like this or this? Even has full open source Arduino firmware. Really an impressive project!

BINGO! Yes, exactly like that. He did such a good job I'd say the hardware development is effectively done. Now just leverage his Sandeep compatible arduino code by adding the Sandeep compatible Mysensors Arduino core software to it, and we're all good to go!

[monte]

@NeverDie but why do you need Mysensors in a wrist watch? :)

[Mishka]

@monte 1) To control all the sensors and 2) to be monitored by the network.

[Jon Raymond]

@NeverDie

If you can fit your code modifications into an nRF52832 then you can buy an off the shelf watch. All the hard work is done. It's even on sale currently :)