STM32配合W5500网卡连接MQTT服务器

【1】W5500网卡

W5500是一种基于TCP/IP协议的网络通讯芯片，可以提供网络连接功能，相当于是一种嵌入式以太网控制器，具有低功耗、高速传输、易于集成等特点。W5500芯片能够支持TCP、UDP、IPv4、ARP、ICMP、IGMP等协议，使得它变得非常适合用于嵌入式设备与互联网之间的通信需求，例如智能家居、工业控制、远程监控等场景。W5500网卡还有一个特点是它支持硬件协议堆栈，这意味着它可以非常快地执行协议栈中的操作，从而大大提高了数据传输的效率。同时，W5500还具有较低的功耗，因此非常适合嵌入式设备这种资源受限的场景。

W5500芯片通过SPI总线与MCU进行通信，MCU需要实现SPI总线协议来控制W5500进行数据交互。

【2】SPI协议

SPI（Serial Peripheral Interface）协议是一种串行外设接口协议，是一种全双工、同步的接口技术，通常用于连接微控制器和外设，例如传感器、存储器、显示器等。SPI协议传输效率高，使用简单，开销较小，因此被广泛应用于嵌入式系统中。

SPI协议使用主从模式，主设备可以控制多个从设备，从设备不能主动向主设备发送数据或信息。SPI协议具有以下几个重要的信号线：

1. SCLK：时钟线，由主设备提供，用于同步主从设备之间的数据传输。
2. MOSI（Master Out Slave In）：主输出从输入线，由主设备提供，用于向从设备发送数据。
3. MISO（Master In Slave Out）：主输入从输出线，由从设备提供，用于向主设备发送数据。
4. SS（Slave Select）：从设备选择信号线，由主设备提供。当主设备需要与某个从设备通信时，将该线电平拉低，以选择需要通信的从设备。

SPI协议的数据传输是基于数据字节的传输，主设备每次通过MOSI线发送一个字节，从设备通过MISO线接受该字节，并回传一个字节。数据的传输顺序可以根据时钟线（SCLK）的极性和相位配置为四种不同的模式。SPI协议支持的模式受闪存、RAM、I/O和模拟/数字转换器等外设和类型的限制。

【3】W5500建立TCP协议通信

以下是STM32通过W5500建立TCP通信，并访问TCP服务器，完成数据收发的示例代码。

代码中使用了STM32 HAL库，W5500的IP地址和端口号需要根据实际情况进行设置。

#include "main.h"
#include "stdio.h"
#include "stm32f1xx_hal.h"
#include "wizchip_conf.h"
#include "socket.h"
#include "dhcp.h"

/* Private variables */
SPI_HandleTypeDef hspi1;

/* Private function prototypes */
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_SPI1_Init(void);
void W5500_Init(void);
uint8_t socket;
uint8_t buf[1024];

int main(void)
{
   
  /* MCU Configuration */
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_SPI1_Init();

  /* W5500 Initialization */
  W5500_Init();

  /* Connect to TCP Server */
  uint8_t server_ip[4] = {
   192, 168, 1, 100};
  uint16_t server_port = 5000;
  uint8_t connected = 0;

  while (!connected)
  {
   
    if (getSn_SR(socket) == SOCK_CLOSED)
    {
   
      socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
      if (socket == 0xFF)
      {
   
        /* Error: Failed to create socket */
      }
      else
      {
   
        /* Configure socket */
        uint8_t dest_ip[4] = {
   192, 168, 1, 200};
        uint16_t dest_port = 5000;
        uint8_t buf[4];
        IINCHIP_WRITE(Sn_DIPR(socket), dest_ip);
        IINCHIP_WRITE(Sn_DPORT(socket), dest_port);
        IINCHIP_SOCKET_CONTROL(socket, Sn_CR_OPEN);
        HAL_Delay(10);

        /* Try to connect to server */
        IINCHIP_SOCKET_CONTROL(socket, Sn_CR_CONNECT);
        HAL_Delay(1000);
        if (getSn_SR(socket) == SOCK_ESTABLISHED)
        {
   
          connected = 1;
        }
        else
        {
   
          /* Connection failed */
          IINCHIP_SOCKET_CONTROL(socket, Sn_CR_CLOSE);
          HAL_Delay(10);
        }
      }
    }
  }

  /* Send Data to Server */
  uint8_t tx_data[4] = {
   0x01, 0x02, 0x03, 0x04};
  write(socket, tx_data, sizeof(tx_data));

  /* Receive Data from Server */
  int rx_len = 0;
  while (1)
  {
   
    rx_len = getSn_RX_RSR(socket);
    if (rx_len > 0)
    {
   
      read(socket, buf, rx_len);
      /* Data received from server, do something */
    }
= SPI_DIRECTION_2LINES;
hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;
hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
hspi1.Init.NSS = SPI_NSS_SOFT;
hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_128;
hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
hspi1.Init.TIMode = SPI_TIMODE_DISABLE;
hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
hspi1.Init.CRCPolynomial = 10;
HAL_SPI_Init(&hspi1);
}
/* GPIO Initialization */
static void MX_GPIO_Init(void) 
{
   
GPIO_InitTypeDef GPIO_InitStruct = {
   0};
__HAL_RCC_GPIOA_CLK_ENABLE();
/*Configure GPIO pin : PA4 */
GPIO_InitStruct.Pin = GPIO_PIN_4;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
}
/* System Clock Configuration */
void SystemClock_Config(void) 
{
   
RCC_OscInitTypeDef RCC_OscInitStruct = {
   0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {
   0};
/** Initializes the RCC Oscillators according to the specified parameters
in the RCC_OscInitTypeDef structure. */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) 
{
   
    Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks */
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK) 
{
   
    Error_Handler();
}
}

【4】封装MQTT协议报文

下面使用MQTT client library for Contiki来连接MQTT服务器。这个库适用于不同的平台，包括STM32。在使用前，需要根据需求进行一些配置，例如： 指定MQTT服务器的地址和端口号，配置MQTT客户端ID和主题等。

#include "contiki.h"
#include "contiki-net.h"
#include "mqtt.h"

#include "stm32f1xx_hal.h"
#include "wizchip_conf.h"
#include "w5500.h"

/* MQTT Configuration */
#define SERVER_IP_ADDR "192.168.1.100"
#define SERVER_PORT 1883
#define MQTT_CLIENT_ID "mqtt_stm32"
#define MQTT_TOPIC "example_topic"

/* Network Configuration */
static wiz_NetInfo gWIZNETINFO = {
    .mac = {
   0x01, 0x02, 0x03, 0x04, 0x05, 0x06},
                                   .ip = {
   192, 168, 1, 200},
                                   .sn = {
   255, 255, 255, 0},
                                   .gw = {
   192, 168, 1, 1},
                                   .dns = {
   8, 8, 8, 8},
                                   .dhcp = NETINFO_STATIC };

/* W5500 Buffer */
static uint8_t buf[2048];

/* Prototypes */
static void MX_SPI1_Init(void);
static void MX_GPIO_Init(void);
void SystemClock_Config(void);
void Error_Handler(void);
void W5500_Select(void);
void W5500_UnSelect(void);
uint8_t W5500_WriteByte(uint8_t b);
uint8_t W5500_ReadByte(void);
void MQTT_Callback(struct mqtt_connection *m, void *userdata, mqtt_event_t event, mqtt_data_t *data);

/* MQTT Connection */
static struct mqtt_connection mqtt_conn;
static struct mqtt_message *msg_ptr = NULL;
static uint8_t mqtt_connected = 0;

PROCESS(mqtt_process, "MQTT Process");

AUTOSTART_PROCESSES(&mqtt_process);

/* MQTT Process */
PROCESS_THREAD(mqtt_process, ev, data)
{
   
  PROCESS_BEGIN();

  /* Initialize W5500 */
  reg_wizchip_cs_cbfunc(W5500_Select, W5500_UnSelect);
  reg_wizchip_spi_cbfunc(W5500_ReadByte, W5500_WriteByte);
  wizchip_init(buf, buf);

  /* Configure Network */
  ctlnetwork(CN_SET_NETINFO, (void*)&(gWIZNETINFO));

  /* DHCP Initialization */
  uint8_t /* Enable DHCP */ dhcp_client_start();

/* Wait for DHCP to finish */
while (gWIZNETINFO.dhcp == NETINFO_DHCP) 
{
   
    HAL_Delay(1000);
    // wait for DHCP to finish }
    /* Print IP Address */
    printf("IP address: %d.%d.%d.%d\n", gWIZNETINFO.ip[0], gWIZNETINFO.ip[1], gWIZNETINFO.ip[2], gWIZNETINFO.ip[3]);
    /* Configure MQTT Connection */
    memset(&mqtt_conn, 0, sizeof(mqtt_conn));
    mqtt_conn.state = MQTT_INIT;
    mqtt_conn.host = SERVER_IP_ADDR;
    mqtt_conn.port = SERVER_PORT;
    mqtt_conn.client_id = MQTT_CLIENT_ID;
    mqtt_conn.user_data = NULL;
    mqtt_conn.user_name = NULL;
    mqtt_conn.password = NULL;
    mqtt_conn.protocol_version = MQTT_VERSION_3_1_1;
    mqtt_conn.keep_alive = 60;
    /* Connect to MQTT Server */
    mqtt_connect(&mqtt_conn);
    /* Wait for MQTT Connection to Finish */
    while (!mqtt_connected) 
    {
   
        PROCESS_PAUSE();
    }
    /* Publish Message to MQTT Server */
    static char msg[100] = "Hello from STM32 using MQTT protocol!";
    msg_ptr = mqtt_msg_publish_init(msg, strlen(msg), MQTT_TOPIC, MQTT_QOS_LEVEL_0, MQTT_RETAIN_OFF);
    mqtt_publish(&mqtt_conn, msg_ptr);
    /* Wait for Message to be Sent */
    while (mqtt_conn.out_buffer_sent == 0) 
    {
   
        PROCESS_PAUSE();
    }
    /* Subscribe to MQTT Topic */
    mqtt_subscribe(&mqtt_conn, MQTT_TOPIC, MQTT_QOS_LEVEL_0);
    /* Loop Forever */
    while (1) 
    {
   
        PROCESS_PAUSE();
    }
    PROCESS_END();
}


/* SPI Initialization / static void MX_SPI1_Init(void) { / SPI1 parameter configuration*/
hspi1.Instance = SPI1;
hspi1.Init.Mode = SPI_MODE_MASTER;
hspi1.Init.Direction = SPI_DIRECTION_2LINES;
hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;
hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
hspi1.Init.NSS = SPI_NSS_SOFT;
hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_128;
hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
hspi1.Init.TIMode = SPI_TIMODE_DISABLE;
hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
hspi1.Init.CRCPolynomial = 10;
HAL_SPI_Init(&hspi1);
}
/* GPIO Initialization */
static void MX_GPIO_Init(void) 
{
   
GPIO_InitTypeDef GPIO_InitStruct = {
   0};
__HAL_RCC_GPIOA_CLK_ENABLE();
/*Configure GPIO pin : PA4 */
GPIO_InitStruct.Pin = GPIO_PIN_4;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
}
/* System Clock Configuration */
void SystemClock_Config(void) 
{
   
RCC_OscInitTypeDef RCC_OscInitStruct = {
   0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {
   0};
/** Initializes the RCC Oscillators according to the specified parameters
in the RCC_OscInitTypeDef structure. */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) 
{
   
    Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks */
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK) 
{
   
    Error_Handler();
}

}

/* Error Handler */
void Error_Handler(void) 
{
   
while (1) 
{
   
    // error } }
    /* W5500 Select */
    void W5500_Select(void) 
    {
   
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
    }
    /* W5500 Unselect */
    void W5500_UnSelect(void) 
    {
   
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
    }
    /* W5500 Write Byte */
    uint8_t W5500_Writebyte(uint8_t b) 
    {
   
        uint8_t res;
        HAL_SPI_TransmitReceive(&hspi1, &b, &res, 1, HAL_MAX_DELAY);
        return res;
    }

/* W5500 Read
byte */ uint8_t W5500_Readbyte(void) 
{
   
    uint8_t b = 0xff;
    HAL_SPI_TransmitReceive(&hspi1, &b, &b, 1, HAL_MAX_DELAY);
    return b;
}
/* MQTT Callback */
void MQTT_Callback(struct mqtt_connection *m, void *userdata, mqtt_event_t event, mqtt_data_t *data) 
{
   
    switch (event) 
    {
   
        case MQTT_EVENT_CONNECTED: printf("MQTT connected\n");
        mqtt_connected = 1;
        break;
        case MQTT_EVENT_DISCONNECTED: printf("MQTT disconnected\n");
        mqtt_connected = 0;
        break;
        case MQTT_EVENT_PUBLISHED: printf("MQTT message published\n");
        break;
        case MQTT_EVENT_SUBACK: printf("MQTT subscribed to topic\n");
        break;
        case MQTT_EVENT_UNSUBACK: printf("MQTT unsubscribed from topic\n");
        break;
        case MQTT_EVENT_DATA: printf("MQTT received message\n");
        printf("Topic: %.*s\n", data->topic_name_size, data->topic_name);
        printf("Message: %.*s\n", data->data_size, (char *)data->data);
        break;
        default: break;
    }
}