How to Use PIC18F458 : Examples, Pinouts, and Specs

The PIC18F458 is an 8-bit microcontroller developed by Microchip Technology. It features a 16-bit instruction set, 32 KB of Flash memory, 1.5 KB of RAM, and a wide range of I/O ports. This microcontroller is designed for embedded applications that demand high performance and low power consumption. Its robust feature set makes it suitable for automotive, industrial, and consumer electronics applications.

• Automotive systems (e.g., CAN bus communication)
• Industrial automation and control
• Consumer electronics
• Data acquisition systems
• Embedded systems requiring low power and high performance

The PIC18F458 is available in a 40-pin PDIP package. Below is the pin configuration and description:

For the complete pinout, refer to the official datasheet.

1. Power Supply: Connect the VDD pin to a 5V power source and the VSS pin to ground.
2. Reset Circuit: Use a pull-up resistor (typically 10 kΩ) on the MCLR pin to enable proper reset functionality.
3. Oscillator Configuration: Connect an external crystal oscillator (e.g., 20 MHz) to the OSC1 and OSC2 pins, along with appropriate capacitors.
4. Programming: Use an ICSP (In-Circuit Serial Programming) tool to program the microcontroller via the MCLR, PGD, and PGC pins.
5. I/O Configuration: Configure the I/O pins as input or output in the software, depending on the application.
6. Peripheral Setup: Initialize peripherals such as ADC, UART, or CAN as required by your application.

• Ensure the operating voltage is within the specified range (4.2V to 5.5V).
• Use decoupling capacitors (e.g., 0.1 µF) near the VDD and VSS pins to reduce noise.
• Avoid leaving unused pins floating; configure them as outputs or connect them to ground via pull-down resistors.
• For CAN communication, ensure proper termination resistors (120 Ω) are used on the CAN bus.

Although the PIC18F458 is a standalone microcontroller, it can communicate with an Arduino UNO via UART. Below is an example of how to send data from the PIC18F458 to an Arduino UNO:

PIC18F458 Code (MPLAB XC8):

#include <xc.h>

// Configuration bits
#pragma config OSC = HS        // High-speed oscillator
#pragma config WDT = OFF       // Watchdog Timer disabled
#pragma config LVP = OFF       // Low Voltage Programming disabled

#define _XTAL_FREQ 20000000    // Define crystal frequency (20 MHz)

void UART_Init(void) {
    TRISC6 = 0;                // TX pin as output
    TRISC7 = 1;                // RX pin as input
    SPBRG = 31;                // Baud rate 9600 for 20 MHz clock
    TXSTAbits.SYNC = 0;        // Asynchronous mode
    TXSTAbits.BRGH = 1;        // High-speed baud rate
    RCSTAbits.SPEN = 1;        // Enable serial port
    TXSTAbits.TXEN = 1;        // Enable transmission
}

void UART_Send(char data) {
    while (!TXSTAbits.TRMT);   // Wait until transmit buffer is empty
    TXREG = data;              // Transmit data
}

void main(void) {
    UART_Init();               // Initialize UART
    while (1) {
        UART_Send('A');        // Send character 'A'
        __delay_ms(1000);      // Delay 1 second
    }
}

Arduino UNO Code:

void setup() {
  Serial.begin(9600);          // Initialize serial communication at 9600 baud
}

void loop() {
  if (Serial.available() > 0) { // Check if data is available
    char received = Serial.read(); // Read the received character
    Serial.print("Received: ");    // Print the received data
    Serial.println(received);
  }
}

1. Microcontroller Not Responding

   • Cause: Incorrect power supply or missing decoupling capacitors.
   • Solution: Verify the power supply voltage and add 0.1 µF capacitors near the VDD and VSS pins.

2. Programming Failure

   • Cause: Incorrect ICSP connections or configuration.
   • Solution: Double-check the connections to the MCLR, PGD, and PGC pins. Ensure the programmer is compatible with the PIC18F458.

3. UART Communication Not Working

   • Cause: Mismatched baud rates or incorrect wiring.
   • Solution: Ensure both devices use the same baud rate and verify the TX and RX connections.

4. Analog Inputs Not Reading Correctly

   • Cause: Improper ADC configuration or noisy input signals.
   • Solution: Verify the ADC setup in the code and use proper filtering for the input signals.

Q: Can the PIC18F458 operate at 3.3V?
A: No, the PIC18F458 requires a minimum operating voltage of 4.2V.

Q: How do I enable the CAN module?
A: The CAN module can be enabled by configuring the appropriate registers (e.g., CANCON, CIOCON) in the software. Refer to the datasheet for detailed instructions.

Q: What is the maximum clock speed of the PIC18F458?
A: The maximum clock speed is 40 MHz when using an external oscillator.

Q: Can I use the PIC18F458 for low-power applications?
A: Yes, the PIC18F458 supports power-saving modes such as Sleep mode, making it suitable for low-power applications.