Specifications

mikroElektronika | Free Online Book | PIC Microcontrollers | Appendix B: Examples
These oscillators are used when it is not necessary to have extremely precise frequency.
RC oscillator
If the operating frequency is not of importance then there is no need for additional expensive components for
stabilization. Instead, a simple RC network, as shown in the figure below, will be enough. Since only the input of the local
oscillator input is in use here, the clock signal with frequency Fosc/4 will appear on the OSC2 pin. Furthermore, that
frequency becomes operating frequency of the microcontroller, i.e. the speed of instruction execution.
External oscillator
If it is required to synchronize the operation of several microcontrollers or if for some reason it is not possible to use any
of the previous schematics, a clock signal may be generated by an external oscillator. Refer to the figure below.
ADDITIONAL COMPONENTS
Regardless of the fact that the microcontroller is a product of modern technology, it is of no use without being connected
to additional components. Simply, the appearance of voltage on the microcontroller pins mean nothing if not used for
performing certain operations (turn something on/off, shift, display etc.).
This section intentionally covers only the most commonly used additional components in practice such as resistors,
transistors, LED diodes, LED displays, LCD displays and RS232 communication circuits.
SWITCHES AND PUSH-BUTTONS
There is nothing simpler than switches and push-buttons! This is definitely the simplest way of detecting the appearance
of a voltage on the microcontroller input pin and there is no need for additional explanation of how these components
operate. Nevertheless, it is not so simple in practice... Then, what is it all about?
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