The Casio Pocket Viewer was a competitor to the Palm Pilot. The two systems even shared the same LCD resolution – 160×160 monochrome. [Tomas’] particular model is an S660, sporting 6 megabytes of ram and an NEC V30MZ (Intel 8086 compatible) processor. Similar to Palm, Casio made an SDK freely available.
The SDK is still available from Casio, and [Tomas] was able to get it running on his PC. Development wasn’t without pitfalls though. The Pocket Viewer SDK was last updated in April of 2001. Software is written in C, but the then new C99 standard is not supported. The SDK does include a simulator and debugger, but it too is not as polished as todays systems – every simulator startup begins with setting the clock and calibrating the touch screen. Keep reading after the jump to learn about the rest of the hurdles he overcame to pull this one off.
The pocket viewer’s only connection to the outside world is through an RS-232 link. [Tomas] was able use the serial link to connect the pocket viewer to his server running custom PHP code. At first he tried to send full screens of data to the PV. This proved to be much too slow at serial speeds. Updating only those sections of the screen which have changed proved to be much faster. In the unlikely event that an entire screen has changed, [Tomas] sends the screen in chunks – so the user still sees activity at the display.
The finishing touch was a power source. The pocket viewer was designed to run on AAA batteries. [Tomas] installed a 3V regulator, but even then the system would reset randomly. The internal DC to DC converter of the Pocket Viewer was causing current spikes that his regulator couldn’t handle. A 100uf capacitor finally stabilized the power supply.
[Tomas] final hack was to add an interface from his garage door to his router. The router updates his server on the garage doors state. The server then formats this information for the pocket viewer, letting [Tomas] know if the garage is open or closed.
We think this is a great example of reusing old hardware. How many of us have an old PDA lying around? It would be great to see more of them end up being use like this, rather than recycled or worse yet, sent to the landfill.