SIOP to LCD Interface
Notes:
The cycling computer can display the following statistics on its Planar Standish 8-digit LCD: temperature, relative humidity, speed, distance traveled, pulse rate, and stopwatch time.
Motorola’s MC14LC5003 is used to simplify the LCD interface. This device multiplexes 32 frontplanes with 4 backplanes to drive up to 128 segments. This is a perfect fit for the Planar Standish LCD which uses 32 frontplanes and 4 backplanes to display eight 15-segment alphanumeric characters.
The decision to use a serially interfaced LCD was prompted by the need to keep the cycling computer code as compact as possible. A microcontroller with built-in LCD drive capability would reduce component count, and possibly cost, but at the expense of requiring more complicated software to manage LCD updates.
On the other hand, a serially interfaced LCD can be managed with simpler, loop-oriented code that treats all updates identically. The resulting message handler is smaller and less complicated than the equivalent code for a direct drive LCD.