stm32的mqtt的库函数代码

下面是基于STM32CubeMX和STM32 HAL库的MQTT客户端代码示例：

#include "mqtt.h"

/* MQTT客户端句柄 */
MQTT_Client_t mqttClient;

/* MQTT回调函数 */
void Mqtt_Callback(MQTT_Client_t *client, char *topic, uint8_t *payload, uint32_t length) {
  /* 处理MQTT消息 */
}

/* 连接MQTT服务器 */
int Mqtt_Connect(void) {
  int ret;
  struct mqtt_connect_client_info_t ci;
  
  /* 初始化MQTT客户端 */
  MQTT_InitClient(&mqttClient, MQTT_BROKER_ADDRESS, MQTT_BROKER_PORT, Mqtt_Callback);
  
  /* 配置MQTT连接信息 */
  memset(&ci, 0, sizeof(ci));
  ci.client_id = "mqtt_client";
  ci.keepalive = 60;
  ci.username = MQTT_USERNAME;
  ci.password = MQTT_PASSWORD;
  
  /* 连接MQTT服务器 */
  ret = MQTT_Connect(&mqttClient, &ci);
  
  return ret;
}

/* 发布MQTT消息 */
int Mqtt_Publish(char *topic, char *payload, uint32_t length) {
  int ret;
  
  /* 发布MQTT消息 */
  ret = MQTT_Publish(&mqttClient, topic, payload, length, 0, 0);
  
  return ret;
}

/* 断开MQTT连接 */
int Mqtt_Disconnect(void) {
  int ret;
  
  /* 断开MQTT连接 */
  ret = MQTT_Disconnect(&mqttClient);
  
  return ret;
}

请注意，这里的`MQTT_BROKER_ADDRESS`和`MQTT_BROKER_PORT`是MQTT服务器的IP地址和端口号，`MQTT_USERNAME`和`MQTT_PASSWORD`是MQTT服务器的用户名和密码。此外，您还需要在`Mqtt_Callback`函数中实现自己的消息处理逻辑。