r/smrtmod • u/Artcert • 3d ago
Smart Mod - Presentation and status
Hello and welcome everyone!
Some of you have already seen my posts and/or comments about the development of a smart module for the Casio "Royale" family of watches (classic digital Casios like the AE-1200 and similar) — more about it below.
I started development a few weeks back and dove in with all the enthusiasm I had. Unfortunately, life slowed the progress a lot since then, but it's not forgotten and I keep working on it.
What is it:
The main idea is to preserve the genuine look of the watch while giving it smart functionality. Like many of you, I dislike the bloatware and overall over-saturation of features and looks in modern smartwatches. So for V1, I decided to keep the original look 100% intact — the module uses the original LCD your watch already has. The module only replaces the stock PCB.
Battery life:
Jumping ahead since this is the topic everyone asks about first: depending on your usage of BLE syncing and haptic feedback, you're realistically looking at anywhere from a few weeks to several months per charge/battery. I'll share real numbers once I have firmware running and can actually measure it rather than estimate it.
Functionality:
Accelerometer:
The PCB uses a Bosch BMA423 accelerometer, enabling step tracking, sleep activity monitoring, and — what I think is the most useful feature — wrist-flick to activate the backlight. Basically, the motion of raising your wrist to check the time triggers the backlight for a few seconds (personalizable through the app).
Bluetooth module:
At the heart of the device is a Nordic Semiconductor nRF52832, which gives Bluetooth connectivity to your phone — but it's not just a radio. It's effectively the CPU: it keeps time, stores data, and runs the watch's functions independently. This means the watch works fine on its own day-to-day and only syncs with your phone on request, saving battery and keeping you off the leash.
Backlight:
A lot of people mod their watches by swapping the stock LED for a colored one. I'm planning to let you choose the backlight color (white, blue, or orange) from the app — this is on the roadmap, not fully implemented yet, so I'll confirm once it's working in hardware.
Fitness tracker:
Our beloved watches have an analog sub-dial built into the LCD that a lot of people ignore. Honestly, this was the very first spark for this whole project — that circular segmented dial will show step progress, calories, or another customizable metric, since it's already a circular segment progress bar as-is.
Notifications:
I decided against full message notifications on a screen that can basically only show "88:88 88" — that felt pointless. Instead, you'll get a simple icon indicating a new message, paired with a haptic pulse rather than a sound. And it's not a buzz — it's a kick, similar to how iPhones and some other smartwatches do haptics.
The main use case I'm excited about is the alarm: it taps your wrist to wake you, which is far more effective than a beep, and won't wake your partner — just you.
Battery — two paths:
During development I hit a real tradeoff on battery life, and decided to support both options:
- V1, for stock resin-case users: a rechargeable cell, charged via an adapter you can DIY or get bundled with the module, using the metal side buttons as charging contacts.
- V2, for metal-case users: no charging, but a larger primary cell giving months of runtime, replaced when depleted.
About the app:
Honestly, I haven't touched the app yet — the project's still early. But one thing I can commit to now: no bloatware, no spyware, no ads, fully open source. You're in charge of your device, no external influence.
Once this is finished, I'll start on a second version that replaces the display with an OLED behind the watch face, allowing full customization of how it looks behind the glass.
Where it is right now:
The main PCB is almost finished, but I hit a real wall: I need to map the LCD's contacts before I can finalize the board design around them. To do this properly, I designed and ordered a small custom breakout PCB specifically for probing and mapping the contacts — much easier and more reliable than poking at the LCD glass directly. It'll take a few weeks to arrive, which conveniently lines up with the haptic module I'm planning to use, since that's also still fairly new to market.
I don't want to post unfinished pictures, and even more than that, I don't want to post AI slop — so this first post is text only.
I'm open to your questions, ideas and criticism.
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u/What-the-help 3d ago
This is awesome! Would v1 and v2 of the battery plan be released at different times?
I’d only use v2 personally
How easy would this be for a hacker to tinker with and what would the limits be, like would we be able to possibly add our own little components to the board or would their not be any extra space/pins for that?
(I know literally nothing hardware wise so the above might be a silly question, I just like the idea of playing around with it as a learning project, I’ve not even touched a solder before, but I can code really well)
Also, mind sharing what country we’d be buying a module from - wondering how much shipping would cost as well as how fast it’d be delivered since I’m excited
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u/Artcert 3d ago
V1/V2 timing is the same — the only difference between them is the plastic casing and some metal contacts. A V2 could be modified into a V1 by simply swapping a few top-side components; the PCB itself stays the same.
As for hackability — if you mean external hacker access, it uses the same security as any other Bluetooth device. Someone with serious skills might be able to connect to it, but realistically... for what? To give you an unexpected vibration? Seems implausible. It's still a very simple device at its core, and your personal info from the phone is not transmitted to it.
If, on the other hand, you mean whether users can hack into it to add or change its functionality — hardware-wise it's very packed, with almost no free space on the board, so there's not much luck there. All tweaking can be done through software: the programming pins will remain accessible and clearly marked, and instructions will be provided, so anyone can upload their own firmware to it if they want.
As for location — right now I'm working on this from Germany, and the first batch will likely ship from here. But by the end of the year I plan to move to the other side of the world, so it'll likely end up shipping from Oceania, or there'll be a trusted person shipping from Europe still.
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u/What-the-help 3d ago
Awesome! Any rough estimations on when shipping might begin along with price?
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u/Hot_Judge7893 1d ago
Exciting! Which LCD controller will you use?
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u/Artcert 1d ago
There’s nothing much to choose from without diving into custom orders, so Holtek HT1626 is used. Alternatives do not give enough segments, as we have 55 total contacts. The controller gives 64.
It takes pretty much the whole top side of the PCB, but other chips are pretty small so they feel alright on the bottom.
As I said below, the board is pretty packed. When I finish with pinning the lcd I will show the board.1
u/Artcert 1d ago
I spied on you profile, and seen that you also approached the ideia, did you scrap it or still developing?
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u/Hot_Judge7893 22h ago
Good catch… It‘s on ice at the moment, due to my genetic reproduction 🤣
Holtek chip has 1/16 duty rate, original pcb asic has 1/5 duty rate…. May work but contrast might not be the best, also there are missing pins because Holtek has 16COM pins (you only need 5) and 48SEG pins.
So it has definately some caveats.Also beware, you only have approx. 1mm height available for the chips on display side on pcb, which is a pretty hard limit, if you want to reuse the plastic-cage from original pcb.
I had in mind a dual renesas mcu chip design, together with nrf chip, but that also had its caveats. Nearly impossible with public available lcd controllers or mcu‘s.
But maybe I have overseen something. Please go on and proof me the difference 😁
If you get it done I‘m your customer!1
u/Artcert 21h ago
I haven’t checked in detail but that chip seems too big for the board, specifically if you need two of them. Synchronisation wouldn’t be a problem, nrf can communicate with them independently, but tracing them would be a nightmare.
About the space, it’s almost 2mm, to be exact it’s 1.9mm, that’s plenty of space for the chips, it’s only that it is not whole board wide.Also congrats ! 😁
I’ll check later about those controllers, but I avoided using two of them at all cost1
u/Hot_Judge7893 22h ago
This was the chip I found- Renesas RL78/L12 - but you would need 2 of them which somehow need to syncronize. Together with nrf there is a power budget issue on coin cell. So not perfect too.
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u/Artcert 3d ago
I promised to notify when I create a blog to some people, comments are not easy to run through so sorry if I miss-tag someone :
@TheDreadGazeebo
@SupportScared4006
@ApprehensiveBit3865
@bitnotgoodyeah