Summary of How to take input with PIC18F4550 Microcontroller
This article explains how to configure input and output pins on the PIC18F4550 microcontroller using the TRIS register. It demonstrates setting pin RA5 as an input connected to a tactile switch and pin RA0 as an output driving an LED. The simple program monitors the switch state and turns the LED on or off accordingly, showcasing basic input handling and output control with the PIC18F4550.
Parts used in the PIC18F4550 Input-Output Control Project:
- PIC18F4550 microcontroller
- LED
- Tactile switch
Any microcontroller based system typically has an input and a corresponding output. Taking simple output with a PIC microcontroller has been explained in LED blinking with PIC18F4550. This article explains how to provide an input to the controller and get a corresponding output using PIC18F4550.
PIC18F4550 has a total of 35 I/O (input-output) pins which are distributed among 5 Ports. Each Port of a PIC microcontroller corresponds to three 8-bit registers (TRIS, PORT & LAT) which should be configured to use the Port for general I/O purpose. For more details, refer LED blinking using PIC.
TRISD | Bit 7 | Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
Value | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
TRISD | Bit 7 | Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
Value | – | – | – | – | – | 1 | – | – |
TRISD | Bit 7 | Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
Value | – | – | – | – | 1 | – | – | 0 |
Project Source Code
###
// Program to control an LED using a switch
// Configuration bits
/* _CPUDIV_OSC1_PLL2_1L, // Divide clock by 2
_FOSC_HS_1H, // Select High Speed (HS) oscillator
_WDT_OFF_2H, // Watchdog Timer off
MCLRE_ON_3H // Master Clear on
*/
void main()
{
ADCON1=0x0F; // Set all pins as digital I/O
CMCON=0x07; // Set all comparators as digital I/O
TRISA.RA0=0; // Configure pin RA0 as output
TRISA.RA5=1; // Configure pin RA5 as input
while(1)
{
if(PORTA.RA5) // If input is high
LATA.LATA0=1; // Turn the LED On
else
LATA.LATA0=0; // Turn the LED Off
}
}
###
