tca9555驱动代码

以下是一个基于C语言的tca9555驱动代码示例：

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <linux/i2c-dev.h>

#define TCA9555_I2C_ADDR 0x20
#define INPUT_PORT_REG_ADDR 0x00
#define OUTPUT_PORT_REG_ADDR 0x01
#define POLARITY_INVERSION_REG_ADDR 0x02
#define CONFIG_REG_ADDR 0x03

#define NUM_PINS 16

int i2c_fd;

void tca9555_write_reg(char reg, char value) {
    char buf[2];
    buf[0] = reg;
    buf[1] = value;
    if (write(i2c_fd, buf, 2) != 2) {
        perror("write");
        exit(1);
    }
}

char tca9555_read_reg(char reg) {
    char value;
    if (write(i2c_fd, &reg, 1) != 1) {
        perror("write");
        exit(1);
    }
    if (read(i2c_fd, &value, 1) != 1) {
        perror("read");
        exit(1);
    }
    return value;
}

void tca9555_set_direction(int pin, int is_input) {
    char config_reg = tca9555_read_reg(CONFIG_REG_ADDR);
    if (is_input) {
        config_reg |= (1 << pin);
    } else {
        config_reg &= ~(1 << pin);
    }
    tca9555_write_reg(CONFIG_REG_ADDR, config_reg);
}

void tca9555_set_output(int pin, int value) {
    char output_port_reg = tca9555_read_reg(OUTPUT_PORT_REG_ADDR);
    if (value) {
        output_port_reg |= (1 << pin);
    } else {
        output_port_reg &= ~(1 << pin);
    }
    tca9555_write_reg(OUTPUT_PORT_REG_ADDR, output_port_reg);
}

int tca9555_get_input(int pin) {
    char input_port_reg = tca9555_read_reg(INPUT_PORT_REG_ADDR);
    return (input_port_reg >> pin) & 1;
}

int main() {
    int i;
    char buf[2];
    char input_port_reg;

    i2c_fd = open("/dev/i2c-1", O_RDWR);
    if (i2c_fd < 0) {
        perror("open");
        exit(1);
    }
    if (ioctl(i2c_fd, I2C_SLAVE, TCA9555_I2C_ADDR) < 0) {
        perror("ioctl");
        exit(1);
    }

    // Set all pins to output
    tca9555_write_reg(CONFIG_REG_ADDR, 0x00);

    // Turn on every other LED
    for (i = 0; i < NUM_PINS; i += 2) {
        tca9555_set_output(i, 1);
    }

    // Read all input pins and print their values
    input_port_reg = tca9555_read_reg(INPUT_PORT_REG_ADDR);
    printf("Input values: ");
    for (i = 0; i < NUM_PINS; i++) {
        printf("%d ", (input_port_reg >> i) & 1);
    }
    printf("\n");

    close(i2c_fd);
    return 0;
}

该代码连接到i2c总线，使用 ioctl() 函数将i2c设备文件的文件描述符设置为TCA9555芯片的地址。然后，使用tca9555_write_reg()和tca9555_read_reg()函数向TCA9555芯片写入和读取寄存器值，并使用tca9555_set_direction()、tca9555_set_output()和tca9555_get_input()函数来控制芯片的输出和读取输入。