MCP2515, PIC16F877A and SPI

[Wajiha Zubair]

Hello,

I have this code and have been trying to make it work but it doesn't give the desired output. I am not sure if the SPI connection is the problem or the the way the message is being sent to the mcp2515. Can anyone help please.

I am using XC8 compiler.

#include <xc.h>
#include <string.h>


// Configuration Bits
#pragma config FOSC = HS // Oscillator Selection bits (HS oscillator)
#pragma config WDTE = OFF // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = ON // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = OFF // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (LVP disabled)
#pragma config CPD = OFF // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off)
#pragma config WRT = OFF // Flash Program Memory Write Enable bits (Write protection off)
#pragma config CP = OFF // Flash Program Memory Code Protection bit (Code protection off)

#define _XTAL_FREQ 8000000 // 20 MHz external oscillator frequency


#ifndef MCP2515_H
#define MCP2515_H

void MCP2515_Reset(void);
void MCP2515_Init(void);
void MCP2515_SendMessage(unsigned char id);
unsigned char MCP2515_ReceiveMessage(unsigned char* id);
void blinkLED(int ms);

#endif

#ifndef SPI_H
#define SPI_H

void SPI_Init(int s);
void SPI_Write(unsigned char data);
unsigned char SPI_Read(void);

#endif

/*
void main() {
//MASTER
TRISD = 0; // Configure RC0 as output for LED
TRISBbits.TRISB3 = 1; // Configure RB3 as input for Button
PORTDbits.RD2 = 1; // Initial LED state

SPI_Init(1); // Initialize SPI
MCP2515_Init(); // Initialize MCP2515

while (1) {
if (PORTBbits.RB3 == 1) { // when button is pressed
PORTDbits.RD2 = 1;
blinkLED(100);


}

unsigned char id;
unsigned char receivedMessage[8];
if (MCP2515_ReceiveMessage(&id)) {
//if (strcmp(receivedMessage, "ON") == 1) {
if ( id == 0x01 ){
PORTDbits.RD2 = 0; // Turn on LED
// __delay_ms(1000);
}
//else if (strcmp(receivedMessage, "OFF") == 0) {
// PORTDbits.RD2 = 1; // Turn off LED
//}
}
}
}
*/

// /*
void main() {
//SLAVE
TRISBbits.TRISB3 = 1; // Configure RB3 as input for Button
TRISD = 0; // CS output (assuming RA5 for CS)
PORTDbits.RD2 = 1;


SPI_Init(0); // Initialize SPI
MCP2515_Init(); // Initialize MCP2515

while (1) {
if (PORTBbits.RB3 == 1) {
PORTDbits.RD2 = 0;
// Button pressed, send CAN message to PIC1
unsigned char message[] = "ON";
MCP2515_SendMessage(0x01); // Send "ON" message
__delay_ms(1000); // Debounce delay
blinkLED(100);

}
if (PORTBbits.RB3 == 0){
PORTDbits.RD2 = 1;
}
}
}
// */


void MCP2515_Reset(void) {
PORTDbits.RD0 = 0; // Select MCP2515
SPI_Write(0xC0); // Send reset command
PORTDbits.RD0 = 1; // Deselect MCP2515
__delay_ms(1); // Wait for the reset to complete
}

void MCP2515_Init(void) {
MCP2515_Reset();
// Additional initialization code here (setting up CAN bitrate, filters, etc.)
}

void MCP2515_SendMessage(unsigned char id) {
PORTDbits.RD0 = 0; // Select MCP2515
SPI_Write(0x40); // Load TX buffer command
SPI_Write(id); // Load identifier
PORTDbits.RD0 = 1; // Deselect MCP2515

PORTDbits.RD0 = 0; // Select MCP2515
SPI_Write(0x80); // Request to send command
PORTDbits.RD0 = 1; // Deselect MCP2515
}

unsigned char MCP2515_ReceiveMessage(unsigned char* id) {
PORTDbits.RD0 = 0; // Select MCP2515
SPI_Write(0x90); // Read RX buffer command
*id = SPI_Read(); // Read identifier
PORTDbits.RD0 = 1; // Deselect MCP2515
return 1; // Indicate a message was received
}

void SPI_Init(int s) {
TRISCbits.TRISC5 = 0; // SDO output
TRISCbits.TRISC4 = 1; // SDI input
TRISCbits.TRISC3 = 0; // SCK output for Master (ignored for Slave)

// SPI control register settings
if (s == 1) {
SSPCON = 0b00100010; // SPI Master mode, clock = Fosc/64
} else {
SSPCON = 0b00100100; // SPI Slave mode, clock = SCK pin
}

SSPSTAT = 0b00000000; // Sample at middle, low to high clock
PORTDbits.RD0 = 1; // Set CS high (inactive)
}

void SPI_Write(unsigned char data) {
SSPBUF = data; // Load data into buffer
//blinkLED(50);
while(!SSPSTATbits.BF); // Wait until transmission is complete
}

unsigned char SPI_Read(void) {
SPI_Write(0x00); // Write dummy data to initiate SPI read
//blinkLED(50);

return SSPBUF; // Return the received data
}

void blinkLED(int ms){
PORTDbits.RD2 = 0;
__delay_ms(ms);
PORTDbits.RD2 = 1;

}

[Ttelmah]

This is a forum for the _CCS_ Compiler, not XC8.
You need to ask on the Microchip forums for help with this, not here.