Control Real World Devices with Your PC

The project illustrates how a PC and microcontroller were interfaced in order to control a servo and sense the value of a potentiometer or any analog input.

A microswitch can be turned ON by the servo and a lamp will then be turned ON by the microswitch. The potentiometer could be a temperature sensor and a heater can be turned ON the servo is a practical application. A relay or other power controller can be used to replace the servo. A simplified version of Basic is used to program the PICAXE and the VB.Net is used for the interface.

The design of the circuit includes 3 AA batteries that run the PICAXEs and for running analog inputs is a 5V regulated supply since the reference voltage does not change. A regulated supply is not needed for simple ON/OFF circuits. A D9 plug is used as the download cable since most modern PCs have a D9 serial port connection.

The circuit is reconfigured as a serial interface circuit where the 22k resistor that used to go to leg 2 now goes to leg 4 while the leg 2 has been grounded.
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