Frequently Asked Questions

Please read this before emailing me. I get the same questions over and over again:

Q) Can I buy one?

A) Yes. I am making a DIY kit available.

Q) When will it be available?

A) Mid May is the target date. I'll update this site the day it's available - really.

Q) How much does it cost?

A) US$115 for the kit, not including the watch band.

Q) Can I buy one fully assembled?

A) Not at present. It takes quite a while to build each one, they have to be soldered, glued, assembled, tested and programmed by hand. I don't have that much free time, but I might build a small batch occasionally to see what interest there is, we'll see.

Q) Is it "open source"?

A) Yes. The software will be released under the GPL license. I encourage people to modify and share their own firmware for it.

Q) I can buy a Casio calculator watch for $20, what makes this different?

A) This is a SCIENTIFIC calculator watch. If you don't understand the significance of that then please go and buy the "4 banger" Casio. The last scientific calculator watch was the Casio CFX-400 20 years ago, and they can go for over $1000 on eBay.

Q) Why doesn't it have a case?

A) The entire concept of the watch was to use off-the-shelf-parts. If it had a professional custom case then it would loose that nerdy DIY look and look like a store bought product. That is missing the entire point of the design! You can't brag about a watch you built yourself if it looks like a store bought product.

The watch is elegant looking without a case, it's a work of art. If you don't "get it" then you 'd better go buy that Casio 4-banger instead.

However, I wouldn't mind doing a "professional" version, but I lack the CAD design skills to do a really good looking case for it. If you have these skills and think you can do something great then get in touch, but no time wasters please. I've had people say they can design a case for it and they don't come through. They don't realise how hard it actually is.

Q) It isn't very "stylish"

A) The watch is built entirely using off-the-shelf parts. i.e. parts available from your local electronics store. It's like building your own car using only bits from your local hardware store. So for a DIY design, the watch is incredibly stylish!

Q) Does it tell the time too?

A) Of course it does! You can even "tweak" the clock to compensate for errors in the crystal oscillator.

Q) Where are all the scientific functions?

A) They are on a "rolling menu key" system that maps to the 6 function keys. It's an elegant system that works very well with few key presses. Some functions only take 2 key presses. Watch the videos and you'll see.

Q) Can I program it myself?

A) You sure can, that's the entire point. The source code for the (free) Microchip C30 compiler will be available for modification, or you can simply write your own firmware from scratch. All you need is a PIC programmer that supports the 24FJ64GA004 chip, and a custom download cable. The connector to make your own programming cable is included in the kit. It is compatible with the MPLAB ICD 2 in-circuit programmer/debugger (recommended).

Q) Is this basically a "computer on your wrist"?

A) Yes. It's more powerful than many of the 8 bit microcomputers from the 80's. It uses a 16bit processor and has 64KB of program memory. It can work up to 8MHz. The 16 character x 2 line dot matrix LCD can display almost anything you want.

Q) Does it have a backlight?

A) Yes it does, but it's quite weak due to limitations in the simplistic circuit used. But you can read the time in the dark. The backlight currently only works in the time/date mode. An updated design may improve on this.

Q) What battery does it use, and what is the battery life?

A) The watch uses either one or two CR2032 lithium batteries (in parallel). Continuous operation would give you 100hrs+ operation, and it should last a few years in "sleep" mode.

Q) What is "sleep" mode?

A) The display on the watch uses a lot of power (comparatively speaking), so it can't be left on continuously. So the watch switches the screen off after a pre-set time period to save power. If you want to see the time or use the calculator you simply hit the MODE button and the watch switches on instantly at the last point it left off, even in the middle of a calculation!

Pressing the STO/RCL button instead will turn the watch on and activate the backlight for a few seconds.

Q) Does it really use RPN?

A) Yes, it really does. This is the worlds first RPN calculator watch. The user can select either RPN or Algebraic mode. The RPN mode is the classic 4 level HP stack with rolling T register. The algebraic mode is like the old (pre-VPAM) Casio's (e.g. FX-82, FX-100 etc) and has 6 levels of parentheses.

Q) Does it do base conversions?

A) The first prototype doesn't, but I plan to add that real soon.

Q) I've seen HP-02 mentioned, what does this mean?

A) HP-02 was the original codename for the watch design. It's a take-off on the Hewlett Packard HP-01 watch.

Q) What's the deal with the "serial port"

A) I have designed in a universal serial port that is connected to the high speed UART inside the PIC chip. This could be used for an RS232, IrDA, SPI or other custom interface. The current firmware does not use this feature, but it's there waiting for someone to make use of it. This uses a 5 pin connector like the ICSP programming interface.

Q) I've heard it's got IR capability too.

A) I have left a free pin on the PIC and space on the top of the PCB to solder an IR LED. The current firmware does not use this, but you could potentially control your TV or whatever with the watch.

Q) How can I update the firmware?

A) You will need to build a programming cable, and have access to a suitable PIC programmer.

Q) Does it measure temperature?

A) The prototype did have a temperature sensor on it. But it was discovered that it picked up too much heat from the users body and gave an unacceptable error on the high side after 5 minutes of being worn. So support for this has been dropped.