joystick interface - an inexpensive unidimensional design

an inexpensive unidimensional design Just as it is very easy to implement an "all or nothing" control (four pos- itions identified by two bits, or eight positions identified by three bits) it is very difficult to realise an inexpensive proportional control. When a reader suggested using an analog to digital converter, such as a 3162, to convert the voltage at the wiper of a joystick potentiometer into a single binary word we recognised the potential of the idea. The IC used is more than just a normal analog to digital con- verter as it provides a multiplexed BCD output (4 bits: pins 2, 1, 15 and 16). The information needed for multiplexing is supplied to three pins: 4, 3 and 5, in descending order of significance. The software controlling the input port must be able to inter- pret this information and the main points which should be borne in mind when writing this software can be gleaned by studying the flowchart shown here. A "0" appears on port A bits 7, 6 and 5 in turn, indicat...