单片机stm32使用ESP8266MQTT AT指令发送json字符串

一、问题描述

    基于文章<单片机stm32使用rt-thread软件包at-device的AT指令>，测试发现使用MQTT AT指令发送主题信息时，直接发送字符串正常，发送json字符串时出问题，提示错误。数据格式的区别如下：

'%s'//正常发送'\'%s\''//提示错误有，发送失败

二、解决办法

    查看文档，发现指令AT+MQTTPUBRAW：发布 MQTT 消息（二进制），该指令格式如下：

AT+MQTTPUBRAW=<LinkID>,<'topic'>,<length>,<qos>,<retain>

参数：

<LinkID>：当前仅支持 link ID 0。

<topic>：MQTT topic，最大长度：128 字节。

<length>：MQTT 消息长度，不同 ESP 设备的最大长度不同：

对于 ESP32 设备：最大长度受到可利用内存的限制；

对于 ESP8266 设备，最大长度受到可利用内存和 MQTT_BUFFER_SIZE_BYTE 宏的限制。该宏的默认值为 512，可在 build.py menuconfig 中设置它的值，以此更改对最大长度的限制。该宏的值 = 消息的最大长度 + MQTT 报头长度（取决于 topic 名称的长度）。

<qos>：发布消息的 QoS，参数可选 0、1、或 2，默认值：0。

<retain>：发布 retain。

三、代码修改

修改代码如下：

#include <rtthread.h>#include <rtdevice.h>#include <at.h>#include <at_device.h>#include <at_log.h>
#define AT_SEND_MQTT_CMD(client, resp, cmd) \ do { \ (resp) = at_resp_set_info((resp), 256, 0, 10 * RT_TICK_PER_SECOND); \ if (at_obj_exec_cmd((client), (resp), (cmd)) < 0) \ { \ result = -RT_ERROR; \ goto __exit; \ } \ } while(0) \
//mqtt 发布主题，测试不同的信息，看是否可以正常发布json信息static int mqtt_at_send(int argc, char **argv){ rt_uint8_t retry_num=3; at_response_t resp = RT_NULL; int result=-RT_ERROR; int i=0; at_client_t client=RT_NULL; struct at_device *device = RT_NULL;
device = at_device_get_by_name(AT_DEVICE_NAMETYPE_NETDEV, 'esp0'); if(device == RT_NULL) { rt_kprintf('no find esp0.\r\n'); return -1; } client=device->client; resp = at_create_resp(128, 0, 10 * RT_TICK_PER_SECOND); if (resp == RT_NULL) { rt_kprintf('no memory for resp create.\r\n'); return -1; } while (retry_num--) {
if(argc == 1)//字符串发送 { /*mqtt pubTopic*/ //AT_SEND_MQTT_CMD(client, resp, 'AT+MQTTPUB=0,\'testTopic1\',\'{\'testTopic1\':\'data_test1\'}\',0,0'); AT_SEND_MQTT_CMD(client, resp, 'AT+MQTTPUB=0,\'testTopic1\',\'test123456\',0,0'); }            else if(argc == 2)//字符串发送 { AT_SEND_MQTT_CMD(client, resp, 'AT+MQTTPUB=0,\'testTopic1\',\'{key0:data_test1}\',0,0'); }            else if(argc == 3)//二进制发送信息 {// if (at_obj_exec_cmd(client, at_resp_set_info(resp, 128, 0, 20 * RT_TICK_PER_SECOND),// 'AT+MQTTPUB=0,\'testTopic1\',\'%s%s\',0,0', argv[1], argv[2]) != RT_EOK)// {// LOG_D('device send failed.\r\n');// } AT_SEND_MQTT_CMD(client, resp, 'AT+MQTTPUBRAW=0,\'testTopic1\',30,0,0'); /* show pubTopic message *///                    for (i = 0; i < resp->line_counts - 1; i++)//                    {//                        LOG_D('%s', at_resp_get_line(resp, i + 1));//                    } rt_device_write(client->device,0,'{\'key0\':\'data_test1\',\'key1\':1}',rt_strlen('{\'key0\':\'data_test1\',\'key1\':1}')); } /* show pubTopic message */ for (i = 0; i < resp->line_counts - 1; i++) { LOG_D('%s', at_resp_get_line(resp, i + 1)); } //rt_thread_mdelay(5000); /* initialize successfully */ result = RT_EOK; break;

__exit: if (result != RT_EOK) { rt_thread_mdelay(1000); rt_kprintf('%s device send retry...', device->name); } } if (resp) { at_delete_resp(resp); } if(result != RT_EOK) { return -1; } return 0; }MSH_CMD_EXPORT(mqtt_at_send, esp8266 mqtt at send message);
static int esp8266_mqtt_at_init(void){ rt_uint8_t retry_num=3; at_response_t resp = RT_NULL; int result=-RT_ERROR; int i=0; at_client_t client=RT_NULL; struct at_device *device = RT_NULL;
device = at_device_get_by_name(AT_DEVICE_NAMETYPE_NETDEV, 'esp0'); if(device == RT_NULL) { rt_kprintf('no find esp0.\r\n'); return -1; } client=device->client; resp = at_create_resp(128, 0, 10 * RT_TICK_PER_SECOND); if (resp == RT_NULL) { rt_kprintf('no memory for resp create.\r\n'); return -1; } while (retry_num--) { /* mqtt para */ AT_SEND_MQTT_CMD(client, resp, 'AT+MQTTUSERCFG=0,1,\'123cli\',\'\',\'\',0,0,\'\''); rt_thread_mdelay(3000); /* mqtt connect para*/ AT_SEND_MQTT_CMD(client, resp, 'AT+MQTTCONNCFG=0,120,0,\'lwt_topic\',\'lwt_msg\',0,0'); rt_thread_mdelay(3000); /* mqtt connect */ AT_SEND_MQTT_CMD(client, resp, 'AT+MQTTCONN=0,\'47.107.99.203\',1883,1'); /* show connect info */ for (i = 0; i < resp->line_counts - 1; i++) { rt_kprintf('%s', at_resp_get_line(resp, i + 1)); } //rt_thread_mdelay(5000); /*mqtt subTopic*/ AT_SEND_MQTT_CMD(client, resp, 'AT+MQTTSUB=0,\'testTopic1\',0'); rt_thread_mdelay(3000); /* initialize successfully */ result = RT_EOK; break;
__exit: if (result != RT_EOK) { rt_thread_mdelay(1000); rt_kprintf('%s device initialize retry...', device->name); } } if (resp) { at_delete_resp(resp); } if(result != RT_EOK) { return -1; } return 0; }//mqtt 参数初始化，订阅主题void mqtt_at_init(int argc, char **argv){ int result=-1; result = esp8266_mqtt_at_init();
if (result!=RT_EOK) { rt_kprintf('mqtt at cmd err.\r\n'); }}MSH_CMD_EXPORT(mqtt_at_init, esp8266 mqtt at cmd demo);

四、测试结果