Scientific Calculator Watch

Posted on Apr 20, 2012

The uWatch comes as a kit of parts. All of the electronic SMD parts on the PCB are pre-assembled. The uWatch is normally in sleep mode and powers down the LCD to save battery power. (approx 3mA LCD on, and 15uA LCD off) To switch the uWatch on press either the MODE key or the RCL/STO key. The uWatch has three `modes`: 1) Time/Date display. 2) Calculator Mode. 3) Setup mode. You can cycle through the modes at any time by pressing the mode key. In Time/Date display mode you can turn on the backlight by pressing the RCL/STO key which turns on the backlight for about 5 seconds. If you press the same key a second time while the backlight is on then it will stay on permanately. Press the key again once to turn the backlight off again after 5 seconds.The calculator mode defaults to RPN mode.

Scientific Calculator Watch
Click here to download the full size of the above Circuit.

After you've tested the LCD is working you can glue it in place with superglue. The bottom of the socket head screws should ideally be flush with the underside of the PCB as shown in the photo, but do NOT force the LCD down to this level if it does not go. As long as the screws penetrate the holes in the main board enough for you to glue them, that is fine. A small bad of glue is applied to the bottom thread of each screw and then the LCD is pushed into place and held until set. This is a fairly tricky operation, as the LCD may tilt during the gluing. The key is to keep the LCD straight and level until the glue sets. After you install the batteries the watch will be ready for use. Pressing the MODE button will turn the watch on. At first the time and date will not be set, so the display may contain some incorrect characters, this is normal. Pressing the MODE button twice will get you to the setup menu from which you can set the time and date and other settings. In the calculator mode you can access the function menus by pressing the MENU key. Pressing the menu key again will cycle through the various menu options. The C key will exit the menu mode. Functions displayed on the LCD can be selected with the F1 to F6 function keys below the screen, the correspond in physical location to the options on the screen. In setup mode use the + and - keys to toggle through the various options. ENTER will select the options....

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