Getting Started with Stm32 : RC522 RFID Reader

#ifndef RC522_H
#define RC522_H

#include "stm32f4xx.h"

// RC522 Pin Definitions
#define RC522_RST_PIN   GPIO_PIN_0
#define RC522_RST_PORT  GPIOB
#define RC522_SS_PIN    GPIO_PIN_12
#define RC522_SS_PORT   GPIOB

// RC522 Commands
#define PCD_IDLE          0x00
#define PCD_AUTHENT       0x0E
#define PCD_RECEIVE       0x08
#define PCD_TRANSMIT      0x04
#define PCD_TRANSCEIVE    0x0C
#define PCD_RESET         0x0F

// RC522 Registers
#define CommandReg        0x01
#define CommIEnReg        0x02
#define DivIEnReg         0x03
#define FIFODataReg       0x09
#define FIFOLevelReg      0x0A
#define ControlReg        0x0C
#define BitFramingReg     0x0D
#define ModeReg           0x11
#define TxControlReg      0x14
#define TxASKReg          0x15

// Function Prototypes
void RC522_Init(void);
void RC522_Reset(void);
void RC522_WriteRegister(uint8_t reg, uint8_t value);
uint8_t RC522_ReadRegister(uint8_t reg);
uint8_t RC522_Communicate(uint8_t command, uint8_t *sendData, uint8_t sendLen, uint8_t *receiveData, uint8_t *receiveLen);
uint8_t RC522_IsNewCardPresent(void);
uint8_t RC522_ReadCardSerial(uint8_t *serial);
void RC522_SelectCard(void);

#endif
    

#include "rc522.h"

// RC522 Initialization
void RC522_Init(void) {
    // Set RST and SS as GPIO outputs
    RCC->AHB1ENR |= RCC_AHB1ENR_GPIOBEN; // Enable GPIOB clock
    GPIOB->MODER |= (0x1 << (RC522_RST_PIN * 2)) | (0x1 << (RC522_SS_PIN * 2)); // Set RST and SS as output
    GPIOB->ODR |= RC522_RST_PIN; // Set RST high
    GPIOB->ODR |= RC522_SS_PIN; // Set SS high

    RC522_Reset(); // Perform a soft reset
    RC522_WriteRegister(TxControlReg, 0x03); // Enable antennas
    RC522_WriteRegister(ModeReg, 0x3D); // Default mode settings
}

// Perform a soft reset
void RC522_Reset(void) {
    RC522_WriteRegister(CommandReg, PCD_RESET);
}

// Write to RC522 Register
void RC522_WriteRegister(uint8_t reg, uint8_t value) {
    GPIOB->ODR &= ~RC522_SS_PIN; // Select the RC522
    SPI2->DR = (reg << 1) & 0x7E; // Send address with write bit
    while (!(SPI2->SR & SPI_SR_TXE)); // Wait for transmission to complete
    SPI2->DR = value; // Send the value
    while (!(SPI2->SR & SPI_SR_TXE)); // Wait for transmission
    GPIOB->ODR |= RC522_SS_PIN; // Deselect the RC522
}

// Read from RC522 Register
uint8_t RC522_ReadRegister(uint8_t reg) {
    GPIOB->ODR &= ~RC522_SS_PIN; // Select the RC522
    SPI2->DR = ((reg << 1) & 0x7E) | 0x80; // Send address with read bit
    while (!(SPI2->SR & SPI_SR_TXE)); // Wait for transmission
    while (!(SPI2->SR & SPI_SR_RXNE)); // Wait for reception
    SPI2->DR = 0x00; // Dummy byte to receive data
    while (!(SPI2->SR & SPI_SR_RXNE)); // Wait for reception
    uint8_t value = SPI2->DR; // Read the received data
    GPIOB->ODR |= RC522_SS_PIN; // Deselect the RC522
    return value;
}

// Check if a new card is present
uint8_t RC522_IsNewCardPresent(void) {
    uint8_t result = RC522_ReadRegister(ControlReg);
    return (result & 0x01); // Return 1 if a new card is present
}

// Read card serial number
uint8_t RC522_ReadCardSerial(uint8_t *serial) {
    uint8_t status = RC522_Communicate(PCD_TRANSCEIVE, NULL, 0, serial, NULL);
    return (status == 0) ? 1 : 0; // Return 1 if successful
}
    

#ifndef I2C_LCD_H
#define I2C_LCD_H

#include "stm32f4xx.h"

// LCD Address
#define LCD_I2C_ADDR 0x27

// Function Prototypes
void LCD_Init(void);
void LCD_SendCommand(uint8_t cmd);
void LCD_SendData(uint8_t data);
void LCD_Print(char *str);
void LCD_Clear(void);

#endif
    

#include "lcd.h" 

// Initialize the LCD
void LCD_Init(void) {
    // Send initialization commands
    LCD_SendCommand(0x38); // Function set
    LCD_SendCommand(0x0C); // Display ON, Cursor OFF
    LCD_SendCommand(0x06); // Entry mode set
    LCD_Clear(); // Clear display
}

// Send a command to the LCD
void LCD_SendCommand(uint8_t cmd) {
    I2C1->CR1 |= I2C_CR1_START; // Generate start condition
    while (!(I2C1->SR1 & I2C_SR1_SB)); // Wait for start condition

    I2C1->DR = LCD_I2C_ADDR << 1; // Send LCD address
    while (!(I2C1->SR1 & I2C_SR1_ADDR)); // Wait for address ack
    (void)I2C1->SR2; // Clear address flag

    I2C1->DR = cmd; // Send command
    while (!(I2C1->SR1 & I2C_SR1_TXE)); // Wait for transfer complete
    I2C1->CR1 |= I2C_CR1_STOP; // Generate stop condition
}

// Send data to the LCD
void LCD_SendData(uint8_t data) {
    LCD_SendCommand(data | 0x40); // Send data with data bit
}

// Print a string on the LCD
void LCD_Print(char *str) {
    while (*str) {
        LCD_SendData(*str++);
    }
}

// Clear the LCD
void LCD_Clear(void) {
    LCD_SendCommand(0x01); // Clear display command
}
    

#include "rc522.h"
#include "lcd.h" 

int main(void) {
    // System Clock Configuration
    SystemClock_Config();

    // Initialize GPIO, SPI, and I2C
    GPIO_Init();
    SPI_Init();
    I2C_Init();

    // Initialize RFID and LCD
    RC522_Init();
    LCD_Init();

    LCD_Print("Waiting for Tag...");

    while (1) {
        if (RC522_IsNewCardPresent()) {
            uint8_t serial[5];
            if (RC522_ReadCardSerial(serial)) {
                LCD_Clear();
                LCD_Print("Tag ID: ");
                for (int i = 0; i < 5; i++) {
                    char buf[3];
                    sprintf(buf, "%02X", serial[i]);
                    LCD_Print(buf);
                }
            }
        }
    }
}