µWatch2 Back Again



#14

Well, it's been around 2 years wince I last floated ideas for my µWatch2 project. Lots of things have happened since then which left zero time and enthusiasm for it, but as with all my projects it's back again.

This time it has a new concept and a new look, which I really like and think will work much better than any previous designs.

It is designed to be a "clip-in" watch calc, so it works equally well as a calc watch, or a tiny pocket calc. Just snap it in and out of the rubber watch band.

Specs are:

- 168x144 mono LCD. No backlight yet, it's designed for very low light conditions. But maybe I can add an even backlight as the LCD is transflective.

- 41mm x 55mm x 10mm alloy or SS case with screw on back plate

- 20 key keypad, with recessed legend overlay. 100g tact switches. 6.5mm key spacing

- Powered from 2 coin cell batteries. (estimate 1+ year life with continuous display)

- Processor choice is up in the air. Suggestions? Needs to be low power, I want to run continuously at 32KHz. Microchip 24F XLP perhaps. Would shoot for say 64KB & 8KB minimum as per the Mk1 uWatch. If it could play chess again I'd be happy.

The LCD and keys are FIRM, and the case design is almost complete to fit actual hardware. According to eMachineShop it should be manufacturable.
First design was 60mm wide with an extra column of keys, but I thought this was too big.

The concept is not a super high end feature watch, with USB and all sorts of fancy stuff. The idea is now low power, long battery life, ruugged, good nerdy calc watch looks, functional, with a basic Casio CFX-400 style shifting key style calc interface.

Might even have an internal micro SD card for storage, maybe

It will have a mineral glass protection for the LCD. Though I'm not sure how these are best mounted. At present it will just sit inside the case against the LCD. If it can some how be glued(?) on a front recess or something then I'll do that.

It will have a 0.1" I/O header pin interface on the left side, for, whatever...

Been thinking about a temperature compensated crystal for a super accurate watch, but that would increase the consumption maybe 10 fold.

Cost is not really factoring into the design, I want this to be a proper commercial quality calc watch you can wear everywhere and have it look good and last.

Buttons and spacing are designed so you can actually use the thing.

Previous designs have gone for powerful 32bit micros, rechargable lithium ion batteries, touch screen or cap sense buttons, and USB etc. But touch screen watches are now a dime a dozen, and I think cap sense will just be too variable at a small key spacing.

I want something with real calc buttons that screams "I'm a NERD!"




It is designed to fit the massively popular existing iPod Nano TikTok watch band. So it's the exact same height as a nano (41mm), but longer, so it would simply hang over each side of the watch band.

As always, feedback welcome.

Dave.


Edited: 20 Aug 2011, 9:55 a.m.


#15

Using the existing TikTok band is a good idea, but you'd want the edges of the case to be very close to the curvature of the iPod Nano for a good fit.

It's not obvious from the photos of the band, but the Nano's belt clip sits "down" in a 1mm or so recess in the bottom of the watch band's case area. This is what secures the watch from potentially sliding sideways out of the case. Your watch back should have something similar.


#16

Quote:
Using the existing TikTok band is a good idea, but you'd want the edges of the case to be very close to the curvature of the iPod Nano for a good fit.

It's not obvious from the photos of the band, but the Nano's belt clip sits "down" in a 1mm or so recess in the bottom of the watch band's case area. This is what secures the watch from potentially sliding sideways out of the case. Your watch back should have something similar.


Given that it's a high quality silicone rubber with a tight fit and almost 40mm of contact surface area on both edges, I would not expect any slip against an anodised aluminium case.

But I could be wrong, will have to suck it and see I guess.

Dave.

#17

For what I can tell after reading the description, this looks like a great tool... sign me up for one! :)
It isn't stated, but I assume it will be RPN, right? Will it have upgradeable firmware, and installable apps?
+1 for the Micro SD, it opens a lot of possibilities for easy backup, data transfer, firmware upgrade, and so on...

About the belt clip recess: if it's to be used also as a tiny desktop calc, I wouldn't want a belt clip on it...

Cristian


#18

Quote:
For what I can tell after reading the description, this looks like a great tool... sign me up for one! :)
It isn't stated, but I assume it will be RPN, right? Will it have upgradeable firmware, and installable apps?
+1 for the Micro SD, it opens a lot of possibilities for easy backup, data transfer, firmware upgrade, and so on...

About the belt clip recess: if it's to be used also as a tiny desktop calc, I wouldn't want a belt clip on it...


I agree on the belt clip.

It will be open source hardware and software, so you can do whatever you want with it.

As stated many times, I am not afraid to say that I am NOT an RPN fanboy, and that I prefer algebraic. So it will have algebraic off the bat. I added RPN to the first watch to make it novel, so will likly do the same with this one.

I couldn't care less about installable apps personally or anything else software, my first priority is to get working hardware.

Upgradable firmware, of course. But whether or not that that's via an easy to use external connector, or via an internal connector, or requires a special programmer etc remains to be seen.

If I stuck a USB connector on the side for instance, then the feature creep starts. You need a faster processor and crystal, and a boot loader to download firmware via the USB etc. Then it chews the batteries, so you start thinking of a USB rechargable lithium ion battery to power it all etc etc...

I'm now thinking that if I use a rubber membrane keypad and don't have any external connectors, then the thing would be fairly water resistant (not waterproof)

Dave.


#19

Dave,

pls make it RPN, pretty please!

hpnut in Malaysia

#20

Hi Dave! Glad to see you are working on this. Though to be honest, I'd be happy with one of the original µWatchs (I discovered it too late to buy).

Just beware of feature creep. If you listen to us, we'll be asking for an HP-42s with a color graphics display and GPS/GSM/WiFi/HDMI/bluetooth/SD card, web cam, and a TV remote control. ;)

But basic HP-45/55 type functionality would do.


#21

Quote:
Hi Dave! Glad to see you are working on this. Though to be honest, I'd be happy with one of the original µWatchs (I discovered it too late to buy).

Trust me, you wouldn't!

It looks far better in the photos than it actually looks and performs in real life.

It was never designed as a commercial product or everyday watch, it was designed to win a design contest and just satisfy my desire to see if it could be done using off the shelf parts.

The battery life was abysmal, the watch band attachment always fell off, and it was a bulky. It was a terrible watch, but a neat project none the less.

Quote:
Just beware of feature creep. If you listen to us, we'll be asking for an HP-42s with a color graphics display and GPS/GSM/WiFi/HDMI/bluetooth/SD card, web cam, and a TV remote control. ;)

I can offer that for sale tomorrow, you can already buy them on ebay :->

Dave.

#22

Actually, an accuracy factor such as the HP 41CX or a correction factor found in the Synchronar Mark one thru four would be more preferable then the temperature compensated crystal

Using the correction factor, a number between 200 and 700 I have gotton the synchronar to within 2 seconds a year on my wrist. Each correction digit (1) is a 4 second per year change to the count of the crystal:

You want to avoid trimming capacitors as they are subject to temperature effects. So finding an accurate cut to the crystal and combinging that with an accuracy factor would solve the power consumption and give the user better control of the watch environment.

Cheers, Geoff

(yes, i have a synchronar)


#23

I have a Synchronar, too, but the batteries have long since ceased to hold a charge. Changing them is a huge pain but I suppose I should get the Dremel out and have a go.

#24

Hi Dave,

As happy Mk1 user I will for sure want a Mk2.
The idea with the TikTok band is nice, I like it!

Quote:
Been thinking about a temperature compensated crystal for a super accurate watch, but that would increase the consumption maybe 10 fold.

With the TI eZ430-Chronos some guys took care of to increase the accuracy, see this article at watchuseek.com
the most accurate astronomical wristwatch in the world? (This link points to an entry about the new Astro-watch firmware, time precission discussion, measurement and analysis is in earlier articles).

The developer there (Catalin) offers several firmware versions, e.g. data-logger, sports-watch, worldtime and astronomical.

eZ430-Chronos uses a 32 kHz crystal, even without any external capacitors.

Hubert

#25

Hi!

Your new watch project looks very promising! Count me in on one...

For me, it dosen't really matter if it will be an RPN or algebraic calculator. If it can do what the HP-01 can do (especially basic time claculations would be nice) and maybe has one or two unshifted (user defineable) constant keys for currency and/or unit conversions, I will be more than happy! If you need votes for adding backlight, count me in on that too. And please don't clutter the little keyboard with triple-shifted functions (but I understand that this has never been your intention anyway).

Does the display allow a constantly running analog watch when not in calculator mode?

And will it fit other iPod nano wristbands other than the one proposed by you? I get very uncomfortable if I wear such large plastic/rubber bracelets for longer and would prefer a "breathing" bracelet made of fabric or leather (there are plenty to chose from and most of them much cheaper than the TocToc band, at least in Europe).

Regards,
max

Edited: 22 Aug 2011, 10:37 a.m.


#26

Quote:
Does the display allow a constantly running analog watch when not in calculator mode?

Yes. Continuous display of anything you want on the dot matrix display. Analog, digital, Klingon, whatever.

Quote:
And will it fit other iPod nano wristbands other than the one proposed by you? I get very uncomfortable if I wear such large plastic/rubber bracelets for longer and would prefer a "breathing" bracelet made of fabric or leather (there are plenty to chose from and most of them much cheaper than the TocToc band, at least in Europe).

Any band that allows added height and extra width would work. Not the fully enclosed types though, as that would require the exact form factor as the Nano. I could do that of course, but then there is no room for the keypad.

Dave.


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