{"id":3464,"date":"2025-03-12T12:44:54","date_gmt":"2025-03-12T12:44:54","guid":{"rendered":"https:\/\/iotthinghub.com\/?p=3464"},"modified":"2025-03-12T14:03:51","modified_gmt":"2025-03-12T14:03:51","slug":"esp8266-as-softap-mode-at-command-mode","status":"publish","type":"post","link":"https:\/\/iotthinghub.com\/?p=3464","title":{"rendered":"ESP8266 as SoftAP mode (AT Command Mode)"},"content":{"rendered":"\n

In our previous article we use ESP8266 working as Station mode. In Station mode we need a wireless router for connecting ESP8266 module. In this article we use SoftAP mode of ESP8266. In Access Mode the ESP8266 works as 2.4GHz wireless router and maximum 4 devices can connect with this router.<\/p>\n\n\n\n

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Before starting please go through my previous article for some basic knowledge of ESP8266 module. Before starting let\u2019s see some command mode that we need in this article.<\/p>\n\n\n\n

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Let\u2019s see the command parameters & there use. Simple AT command return OK string with carriage return & new line. If we send ATE0 it will stop echo otherwise echo come. Command AT+CWMODE define the mode of operations. In this article we use ESP8266 as a router HUB or access point of a network we define AT+CWMODE=2. After define the mode of operation it is time to give some name of your WiFi network provided with a password and IP address for accessing that network.<\/p>\n\n\n\n

CMD> AT+CWSAP = “SSID”, “Password”, channel ID, encryption, Devices, SSID hidden<\/p>\n\n\n\n

Provide any name, password & channel ID you want. ESP8266 use different types of Wi-Fi security protocols that use Pre-Shared Keys (PSK) for authentication.<\/p>\n\n\n\n

1. WPA-PSK (Wi-Fi Protected Access – Pre-Shared Key) <\/p>\n\n\n\n

   – Uses TKIP (Temporal Key Integrity Protocol) for encryption. <\/p>\n\n\n\n

   – More secure than WEP, but still vulnerable to attacks. <\/p>\n\n\n\n

   – Older and considered less secure compared to WPA2. <\/p>\n\n\n\n

2. WPA2-PSK (Wi-Fi Protected Access 2 – Pre-Shared Key) <\/p>\n\n\n\n

   – Uses AES (Advanced Encryption Standard) for encryption, which is much stronger than TKIP. <\/p>\n\n\n\n

   – More secure than WPA-PSK. <\/p>\n\n\n\n

   – Standard for most modern Wi-Fi networks. <\/p>\n\n\n\n

3. WPA\/WPA2-PSK (Mixed Mode) <\/p>\n\n\n\n

   – Supports both WPA-PSK (TKIP) and WPA2-PSK (AES). <\/p>\n\n\n\n

   – Allows older devices that only support WPA to connect while still allowing newer devices to use WPA2. <\/p>\n\n\n\n

   – Less secure than forcing WPA2-only, as attackers could exploit WPA vulnerabilities. <\/p>\n\n\n\n

Chose any protocol level, here I chose WPA\/WPA2-PSK (Mixed Mode). The other 2 parameters has there default values, so no need for assignation or change. For example to set a WiFi Router with name: “IoTtgingHuB”, password “12345678” with channel ID 5 and security level 4 as follow-<\/p>\n\n\n\n

       AT+CWSAP=”IoTtgingHuB”,”12345678″,5,4\\r\\n<\/p>\n\n\n\n

CMD> AT+CIPAP= “IP”, “GateWay”, “SubNetmask”<\/p>\n\n\n\n

The default APIP is 192.168.4.1, but it can be changed. ESP8266 only support class C IP address. A Class C IP address is a part of the IPv4 address classification system that was originally used to define network sizes. Address Range: 192.0.0.0 to 223.255.255.255 with Default Subnet Mask 255.255.255.0. Let\u2019s use IP: 192.168.10.7, Gateway IP: 192.168.10.7 & Sub Netmask: 255.255.255.0 as-<\/p>\n\n\n\n

     AT+CIPAP=”192.168.10.7″,”192.168.10.7″,”255.255.255.0″\\r\\n<\/p>\n\n\n\n

After configuring the IP & gateway create a server with multiple connections with server port 80.<\/p>\n\n\n\n

    AT+CIPMUX=1\\r\\n    & AT+CIPSERVER=1,80\\r\\n<\/p>\n\n\n\n

Let\u2019s create a code for setup function. Here I use UART1 with external interrupt function. Please go through my previous article for more details.<\/p>\n\n\n

\nchar WIFI_NAME[] ="IoTtgingHuB";                      \/\/ Create a WiFi Name\nchar WIFI_PASS[] ="12345678";                         \/\/ Create a WiFi Password\nchar WIFI_AP_IP[]="192.168.10.7";                     \/\/ Create a WiFi AccessPoint\nchar display[1023],wifi_send[1023],RX_ST[1023];\nESP8266_TX("AT\\r\\n","OK",4000);                       \/\/ Device Checking\nESP8266_TX("ATE0\\r\\n","OK",4000);                     \/\/ ECHO OFF\nESP8266_TX("AT+CWMODE=2\\r\\n","OK",4000);              \/\/ SoftAP Mode\nsprintf(wifi_send,"AT+CWSAP=\\"%s\\",\\"%s\\",5,4\\r\\n",WIFI_NAME,WIFI_PASS);\nESP8266_TX(wifi_send,"OK",8000);                      \/\/ Create AccessPoint Server\nsprintf(wifi_send,"AT+CIPAP=\\"%s\\",\\"%s\\",\\"255.255.255.0\\"\\r\\n",WIFI_AP_IP,WIFI_AP_IP);\nESP8266_TX(wifi_send,"OK",8000);                      \/\/ Create AccessPoint IP\nESP8266_TX("AT+CIPMUX=1\\r\\n","OK",4000);              \/\/ Create Multiconnection\nESP8266_TX("AT+CIPSERVER=1,80\\r\\n","OK",4000);        \/\/ Create Server Port 80\nvoid ESP8266_TX(char *b_send,char *return_string,uint16_t delay_time)\n{\n            char ESP8266_TX[10];\n\tsprintf(ESP8266_TX,"%s",return_string);\n            sprintf(wifi_send,"%s",b_send);\n\tHAL_UART_Transmit(&huart1,(uint8_t*)wifi_send,strlen(wifi_send),1000);\n\twhile(1)\n\t{\n\t\tsprintf(RX_ST,"%s",display);\n\t\tif(strstr(RX_ST,ESP8266_TX)) break;\n\t}\n\tHAL_Delay(delay_time);\n\tmemset (display, '\\0',1023);                       \/\/ clear the buffer\n\tmemset (wifi_send,'\\0',1023);                      \/\/ clear the buffer\n\tmemset (RX_ST, '\\0',1023);                         \/\/ clear the buffer\n\tcount=0;\n}\n<\/pre><\/div>\n\n\n
The interrupt callback function as follow-<\/p>\n\n\n
\nuint8_t rx_char;\nuint16_t count;\nextern UART_HandleTypeDef huart1;\n\/\/-------------- Rx Callback Function -----\nvoid HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)\n{\n  if(huart->Instance==USART1 )\n  {\n    display[count++]=rx_char;\n    HAL_UART_Receive_IT(&huart1,&rx_char,1);\n  }\n}\n<\/pre><\/div>\n\n\n
Now it is time to send data to the Access Network through IP: 192.168.10.7:80. After connecting a device either PC or Mobile through WiFi password, open any browser terminal and type 192.168.10.7. When we enter the IP address into the browser, it will return a link ID for interface with full of the browser information. After gating the link ID our next command is to send data to the browser.<\/p>\n\n\n\n
CMD>  AT+CIPSEND=”link ID”, “length of the string”<\/p>\n\n\n\n
If you want only a single device can connect at a time by default the link ID is 0 no need to input, but in multi-connection mode any 4 device can connect at a time & link ID 0~4. After getting link ID send the string length, the ESP8266 can support maximum 2048 bytes of data. We send a total webpage data in HTML format and according to the browser response just simply turn on\/off the load.<\/p>\n\n\n\n
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HTML code: Off condition<\/p>\n\n\n
\n<!DOCTYPE html> <html>\n<head><meta name=\\"viewport\\" content=\\"width=device-width, initial-scale=1.0, user-scalable=no\\">\n<title>Load Control<\/title>\n<style>html { font-family: ZCOOL XiaoWei; display: inline-block; margin: 2px auto; text-align: center;}body{margin-top: 40px;}\nh1 {color: #0e18f3;margin: 45px auto 25px;}\nh3 {color: #050505;margin-bottom: 40px;}\n.button {display: block;width: 60px;background-color: #b589f0;border: none;color: white;padding: 15px 25px;text-decoration: none;font-size: 20px;margin: 0px auto 30px;cursor: pointer;border-radius: 5px;}\n.button-on {background-color: #b589f0;}\n.button-on:active {background-color: #2fd4e0;}\n.button-off {background-color: #65537a;}\n.button-off:active {background-color: #2fd4e0;}\n p {font-size: 16px;color:#040404;margin-bottom: 12px;}\n<\/style><\/head><body><h1>Simple Web Server<\/h1>\n<h3> IoT ThingHuB <\/h3>\n<p>LOAD Status: OFF<\/p>\n<a class=\\"button button-on\\" href=\\"\/loadon\\">ON<\/a>\n<\/body>\n<\/html>\n<\/pre><\/div><\/div>\n\n\n\n
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HTML code: On condition<\/p>\n\n\n
\n<!DOCTYPE html> <html>\n<head><meta name=\\"viewport\\" content=\\"width=device-width, initial-scale=1.0, user-scalable=no\\">\n<title>Load Control<\/title>\n<style>html { font-family: ZCOOL XiaoWei; display: inline-block; margin: 2px auto; text-align: center;}body{margin-top: 40px;}\nh1 {color: #0e18f3;margin: 45px auto 25px;}\nh3 {color: #050505;margin-bottom: 40px;}\n.button {display: block;width: 60px;background-color: #b589f0;border: none;color: white;padding: 15px 25px;text-decoration: none;font-size: 20px;margin: 0px auto 30px;cursor: pointer;border-radius: 5px;}\n.button-on {background-color: #b589f0;}\n.button-on:active {background-color: #2fd4e0;}\n.button-off {background-color: #65537a;}\n.button-off:active {background-color: #2fd4e0;}\n p {font-size: 16px;color:#040404;margin-bottom: 12px;}\n<\/style><\/head><body><h1>Simple Web Server<\/h1>\n<h3> IoT ThingHuB <\/h3>\n<p>LOAD Status: ON<\/p>\n<a class=\\"button button-off\\" href=\\"\/loadoff\\">OFF<\/a>\n<\/body>\n<\/html>\n<\/pre><\/div><\/div>\n<\/div>\n\n\n\n
Assume the link id is 0 & in on condition the total html character is 942 bytes. The command \u2013<\/p>\n\n\n\n
                AT+CIPSEND=0,941\\r\\n <\/p>\n\n\n\n
Wrap return “>” after execute command. Send the full html code & terminate with AT+CIPCLOSE =” link ID”. Please wait at least 1 second before sending next AT command. Interesting that if we send AT+CIPCLOSE =5 all connections will be closed. Here I describe the basic structure & full steps one by one. It is not best practice to use STM32 as core & ESP8266 as slave, because the ESP8266 can properly handle all the command & a development board for lots of more function. We will do all the staff with only a single ESP8266 module in some other article. For device setting & how it works please see my YouTube video, keep learning.<\/p>\n\n\n\n
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