Designing a wristwatch with 7-segmetn LEDs

[jared_Pham]

Hello everyone,

I'm a very new face in the world of electronics and all your help will make me grow faster. One of my lame points is that i have few chances to apply what i've learned into real life.

The reason i'm posting this is currently i'm trying to design a digital wristwatch (as small as possible) which displays time, date-month-year and can be adjusted by users. I'm gonna using leds (i think 7-segment LEDs may work) but i dunno how to start. i can use well ICs for analog circuits but i think this problem involves digital ones.

I hope you dont mind giving some ideas or any sources where i can develop my knowledge of digital controllers.

Regards.

 

[magnatro]

there are dedicated ICs for this.

 

[jared_Pham]

thank you man! but you mean ICs controlled by digital system or what ? because i already found out those ICs (using analog circuits) might cost much more than it should. hope you wont be bothered with my questions 'cause i goddamn have a little of experience on this.

 

[Reloadron]

Years ago HP made several lines of calculators using tiny LED displays. They were discontinued. I am not going to try and dissuade you from your project but something you need to consider is the power consumption of even small LED displays for an application like a watch. Most watches use the much more efficient LCD (Liquid Crystal Display) rather than a LED (Light Emmiting Diode) type display. Watches do not allow space for large batteries. Questions are most welcome but as I said, creating a watch from scratch is a complex project, doing it using a LCD display is not at all practical due to the power consumed by the display.

Just My Take
Ron

 

[crutschow]

The old wrist watches, that had LED displays, had a PB switch to turn-on the LEDs only when you wanted to see the time because of the high power consumption of the LEDs. Some later units used an inertia switch, so you just had to flick your wrist to momentarily turn on the display. Even then the battery life tended to be short.

The wrist watch ICs are a single IC with all the circuitry to do wrist watch functions, such as crystal oscillator, time, day, date, stopwatch, alarm, display driver, etc. Those ICs are all CMOS digital with no analog.

You could conceivably design a wristwatch with a small, very low power microprocessor, but it's rather reinventing the wheel.

 

[crutschow]

Years ago HP made several lines of calculators using tiny LED displays. They were discontinued.

I had one of those and it would typically run for only a few hours on the NiCd batteries before needing recharging, and they only seemed to last a year or so in normal service before needing replacement (I think the batteries would tend to overcharge when left on the charger).

The first HP calculator with an LCD display I bought to replace it used three small button cell non-rechargeable batteries in place of the large AA size NiCds in the LED version. The button cells would typically last several years of normal daily use before needing replacement, longer than the lifetime of the NiCds in the LED calculator.

 

[jared_Pham]

Thank you all! I don't wanna spam but I have to post this just to express my appreciation to you guys. All your sharing of knowledge will benefit beginners like me.