If the pin is configured to be an input pin, then you’ll be reading (polling) its state several times within your program. Configure The Pin, determine the data direction, whether it’s an Input or Output.The registers dedicated to PORTA pins are (TRISA & PORTA), and the registers dedicated to PORTB pins are (TRISB & PORTB), and so on.Ĭontrolling or driving the I/O port is a pretty easy process. There are basically a couple of registers dedicated to each I/O port to control its operation. For this tutorial, we’ll be using PORTB for our Demo. Then the other ones will be using the exact same concept and working in a similar way. Generally speaking, the I/O ports are operating similarly which mean that you only need to investigate one of them. How does a digital input/output port work? Which is the case for PORTC & PORTD as you may have noticed
The pins of every single port may not be in consecutive order physically on the chip. However, some I/O ports may have less than 8-pins as in our PIC16F877A for examples. It’s common in 8-Bit microcontrollers to have I/O ports each of which has up to 8-pins. In our MCU there are 5 digital Input/output ports. As shown below from the PIC16F877A datasheet, the GPIO pins are clustered in PORTs.Īs you may have noticed that the pins are named and that’s why this is called “ PORTA“. Used for restarting the MCU on purpose.Įxcept for the special function pins, all the other pins are GPIOs. Those couple of pins are used to provide the MCU with the oscillator clock input it needs. The special (non-GPIO) pins are usually the following ones: In fact, most of the pins in a typical microcontroller are GPIO pins except for some special pins. GPIO stands for “ General Purpose Input/Output pins“. Component Name Buy On 1 PIC16F877A Add 1 BreadBoard Add 3 LEDs Add Add 2 Push Buttons Add 1 Resistors Kit Add Add 1 Capacitors Kit Add Add 1 Jumper Wires Pack Add Add 1 LM7805 Voltage Regulator (5v) Add 1 Crystal Oscillator Add 1 PICkit2 or 3 Programmer Add 1 9v Battery or DC Power Supply Add Add Add
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