用C实现GPIO模拟IIC，可管理多个子设备，并添加注释

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define HIGH 1
#define LOW 0

// 定义GPIO引脚编号
#define SDA 2
#define SCL 3

// 定义IIC通信速率
#define IIC_SPEED 100000

// 定义IIC总线状态
#define IIC_IDLE 0
#define IIC_START 1
#define IIC_STOP 2
#define IIC_ACK 3
#define IIC_NACK 4

// 定义IIC设备地址
#define ADDR_TEMP 0x48
#define ADDR_EEPROM 0xA0

// 定义IIC设备状态
#define DEVICE_IDLE 0
#define DEVICE_BUSY 1

// 定义IIC设备结构体
typedef struct {
int addr; // 设备的IIC地址
int state; // 设备的状态
} iic_device_t;

// 定义IIC总线状态变量
int iic_state = IIC_IDLE;

// 定义IIC设备数组
iic_device_t iic_devices[] = {
{ADDR_TEMP, DEVICE_IDLE},
{ADDR_EEPROM, DEVICE_IDLE},
};

// 初始化GPIO引脚
void init_gpio(int pin) {
// TODO: 实现GPIO初始化
}

// 设置GPIO引脚状态
void set_gpio(int pin, int value) {
// TODO: 实现GPIO设置
}

// 获取GPIO引脚状态
int get_gpio(int pin) {
// TODO: 实现GPIO读取
return LOW;
}

// 等待一段时间，以实现IIC通信速率控制
void delay() {
usleep(1000000 / IIC_SPEED);
}

// 发送IIC起始信号
void iic_start() {
set_gpio(SDA, HIGH);
delay();
set_gpio(SCL, HIGH);
delay();
set_gpio(SDA, LOW);
delay();
set_gpio(SCL, LOW);
delay();
iic_state = IIC_START;
}

// 发送IIC停止信号
void iic_stop() {
set_gpio(SDA, LOW);
delay();
set_gpio(SCL, HIGH);
delay();
set_gpio(SDA, HIGH);
delay();
iic_state = IIC_STOP;
}

// 发送IIC应答信号
void iic_ack() {
set_gpio(SDA, LOW);
delay();
set_gpio(SCL, HIGH);
delay();
set_gpio(SCL, LOW);
delay();
set_gpio(SDA, HIGH);
delay();
iic_state = IIC_ACK;
}

// 发送IIC非应答信号
void iic_nack() {
set_gpio(SDA, HIGH);
delay();
set_gpio(SCL, HIGH);
delay();
set_gpio(SCL, LOW);
delay();
set_gpio(SDA, LOW);
delay();
iic_state = IIC_NACK;
}

// 发送一个字节的数据
void iic_send_byte(int data) {
int i;
for (i = 0; i < 8; i++) {
if ((data & 0x80) == 0) {
set_gpio(SDA, LOW);
} else {
set_gpio(SDA, HIGH);
}
delay();
set_gpio(SCL, HIGH);
delay();
set_gpio(SCL, LOW);
delay();
data <<= 1;
}
}

// 接收一个字节的数据
int iic_receive_byte() {
int i;
int data = 0;
set_gpio(SDA, HIGH);
delay();
for (i = 0; i < 8; i++) {
data <<= 1;
set_gpio(SCL, HIGH);
delay();
if (get_gpio(SDA) == HIGH) {
data |= 0x01;
}
set_gpio(SCL, LOW);
delay();
}
return data;
}

// 发送IIC设备地址和操作类型
int iic_send_addr(int device_addr, int operation) {
int ack;
iic_send_byte((device_addr << 1) | operation);
ack = get_gpio(SDA);
if (ack == LOW) {
iic_state = IIC_ACK;
} else {
iic_state = IIC_NACK;
}
return ack;
}

// 读取IIC设备的数据
int iic_read(int device_addr, int reg_addr, int len, char *buf) {
int i;
int ack;
iic_device_t *device = NULL;
for (i = 0; i < sizeof(iic_devices) / sizeof(iic_device_t); i++) {
if (iic_devices[i].addr == device_addr) {
device = &iic_devices[i];
}
}
if (device == NULL) {
return -1;
}
if (device->state == DEVICE_BUSY) {
return -1;
}
device->state = DEVICE_BUSY;
iic_start();
ack = iic_send_addr(device_addr, 0);
if (ack == LOW) {
iic_send_byte(reg_addr);
ack = get_gpio(SDA);
if (ack == LOW) {
iic_start();
ack = iic_send_addr(device_addr, 1);
if (ack == LOW) {
for (i = 0; i < len - 1; i++) {
buf[i] = iic_receive_byte();
iic_ack();
}
buf[len - 1] = iic_receive_byte();
iic_nack();
}
}
}
iic_stop();
device->state = DEVICE_IDLE;
return 0;
}

// 写入数据到IIC设备
int iic_write(int device_addr, int reg_addr, int len, char *buf) {
int i;
int ack;
iic_device_t *device = NULL;
for (i = 0; i < sizeof(iic_devices) / sizeof(iic_device_t); i++) {
if (iic_devices[i].addr == device_addr) {
device = &iic_devices[i];
}
}
if (device == NULL) {
return -1;
}
if (device->state == DEVICE_BUSY) {
return -1;
}
device->state = DEVICE_BUSY;
iic_start();
ack = iic_send_addr(device_addr, 0);
if (ack == LOW) {
iic_send_byte(reg_addr);
ack = get_gpio(SDA);
if (ack == LOW) {
for (i = 0; i < len; i++) {
iic_send_byte(buf[i]);
ack = get_gpio(SDA);
if (ack == HIGH) {
break;
}
}
}
}
iic_stop();
device->state = DEVICE_IDLE;
if (ack == LOW) {
return 0;
} else {
return -1;
}
}

int main() {
char buf[10];
iic_read(ADDR_TEMP, 0x00, 2, buf);
printf("Temperature: %d.%d\n", buf[0], buf[1]);
return 0;
}