In this thesis, the automation of the long term and cyclic processes by using a programmable control unit is aimed. To achieve this goal, timing relays and various microcontrollers are investigated. PIC microcontroller is chosen to implement the control unit due to its advantages like high speed, Harvard and RISC architecture, low cost and flexibility for programming. Theory of the PIC microcontrollers is studied and a controller unit to be used in the mentioned processes is designed. Some features are added to the device to widen the application fields and consequently a multi-purpose programmable controller is realized. In the device, Microchip PIC16F877 is used as the microcontroller. The code of the controller is written in Assembly Language and is compiled with MPASM. This controller counts the signals coming from internal Timer 555 or external signals and activates ten different outputs in order. The operating times of the outputs can be changed by a keypad and shown in a display. By keeping the number of the used ports of the microcontroller, as few as possible, room for the future improvements and additions is provided.