This tutorial provides AT commands based on ESP8266_NONOS_SDK and explain how to use them. AT command set is divided into: Basic AT commands, Wi-Fi AT commands, and TCP/IP AT commands.
ESP8266 is a powerful controller with 4Mbytes of Flash and 84Kbytes of RAM. Then why you should use it as just Serial to WiFi module. I recommend use ESP with direct flashing i.e. without using AT commands.
You can Download Complete AT command set for ESP8266 NodeMCU here.
AT Commands Firmware
AT commands will not work if ESP8266 not flashed with AT Firmware.
Downloading AT Firmware into the Flash. Please refer to ESP8266_NONOS_SDK/bin/at/readme.txt for instructions on how to download AT firmware into flash. Please use Espressif’s official Flash Download Tools to download the firmware. Make sure you select the corresponding flash size.
Espressif’s official Flash Download Tools: Espressif Download Tool
Basic AT commands of NodeMCU ESP8266
| Commands | Description |
| AT | Tests AT startup. |
| AT+RST | Restarts the module. |
| AT+GMR | Checks version information. |
| AT+GSLP | Enters Deep-sleep mode. |
| ATE | Configures echoing of AT commands. |
| AT+RESTORE | Restores the factory default settings of the module. |
| AT+UART | UART configuration. [deprecated] |
| AT+UART_CUR | The current UART configuration. |
| AT+UART_DEF | The default UART configuration, saved in flash. |
| AT+SLEEP | Configures the sleep modes. |
| AT+WAKEUPGPIO | Configures a GPIO to wake ESP8266 up from Light-sleep mode. |
| AT+RFPOWER | Sets the maximum value of the RF TX Power. |
| AT+RFVDD | Sets the RF TX Power according to VDD33. |
| AT+RFAUTOTRACE | Sets RF frequency offset trace. |
| AT+SYSRAM | Checks the available RAM size. |
| AT+SYSADC | Checks the ADC value. |
| AT+SYSIOSETCFG | Sets configuration of IO pins. |
| AT+SYSIOGETCFG | Gets configuration of IO pins. |
| AT+SYSGPIODIR | Configures the direction of GPIO. |
| AT+SYSGPIOWRITE | Configures the GPIO output level |
| AT+SYSGPIOREAD | Checks the GPIO input level. |
Wi-Fi AT commands of ESP8266
| Commands | Description |
| AT+CWMODE | Sets the Wi-Fi mode (Station/AP/Station+AP). [@deprecated] |
| AT+CWMODE_CUR | Sets the Wi-Fi mode (Station/AP/Station+AP); configuration not saved in the flash. |
| AT+CWMODE_DEF | Sets the default Wi-Fi mode (Station/AP/Station+AP); configuration saved in the flash. |
| AT+CWJAP | Connect to an AP. [@deprecated] |
| AT+CWJAP_CUR | Connects to an AP; configuration not saved in the flash. |
| AT+CWJAP_DEF | Connects to an AP; configuration saved in the flash. |
| AT+CWLAPOPT | Sets the configuration of command AT+CWLAP. |
| AT+CWLAP | Lists available APs. |
| AT+CWQAP | Disconnects from an AP. |
| AT+CWSAP | Sets the configuration of the ESP8266 SoftAP. [@deprecated] |
| AT+CWSAP_CUR | Sets the current configuration of the ESP8266 SoftAP; configuration not saved in the flash. |
| AT+CWSAP_DEF | Sets the configuration of the ESP8266 SoftAP; configuration saved in the flash. |
| AT+CWLIF | Gets the Station IP to which the ESP8266 SoftAP is connected. |
| AT+CWDHCP | Enables/Disables DHCP. [@deprecated] |
| AT+CWDHCP_CUR | Enables/Disables DHCP; configuration not saved in the flash. |
| AT+CWDHCP_DEF | Enable/Disable DHCP; configuration saved in the flash. |
| AT+CWDHCPS_CUR | Sets the IP range of the DHCP server; configuration not saved in the flash. |
| AT+CWDHCPS_DEF | Sets the IP range of the DHCP server; configuration saved in the flash. |
| AT+CWAUTOCONN | Connects to an AP automatically on power-up. |
| AT+CIPSTAMAC | Sets the MAC address of the ESP8266 Station. [@deprecated] |
| AT+CIPSTAMAC_CUR | Sets the MAC address of the ESP8266 Station; configuration not saved in the flash. |
| AT+CIPSTAMAC_DEF | Sets the MAC address of ESP8266 station; configuration saved in the flash. |
| AT+CIPAPMAC | Sets the MAC address of the ESP8266 SoftAP. [@deprecated] |
| AT+CIPAPMAC_CUR | Sets the MAC address of the ESP8266 SoftAP; configuration not saved in the flash. |
| AT+CIPAPMAC_DEF | Sets the MAC address of the ESP8266 SoftAP; configuration saved in the flash. |
| AT+CIPSTA | Sets the IP address of the ESP8266 Station. [@deprecated] |
| AT+CIPSTA_CUR | Sets the IP address of the ESP8266 Station; configuration not saved in the flash. |
| AT+CIPSTA_DEF | Sets the IP address of the ESP8266 Station; configuration saved in the flash. |
| AT+CIPAP | Sets the IP address of ESP8266 SoftAP. [@deprecated] |
| AT+CIPAP_CUR | Sets the IP address of ESP8266 SoftAP; configuration not saved in the flash. |
| AT+CIPAP_DEF | Sets the IP address of ESP8266 SoftAP; configuration saved in the flash. |
| AT+CWSTARTSMART | Starts SmartConfig. |
| AT+CWSTOPSMART | Stops SmartConfig. |
| AT+CWSTARTDISCOVER | Enables the mode that ESP8266 can be found by WeChat. |
| AT+CWSTOPDISCOVER | Disables the mode that ESP8266 can be found by WeChat. |
| AT+WPS | Sets the WPS function. |
| AT+MDNS | Sets the MDNS function. |
| AT+CWHOSTNAME | Sets the host name of the ESP8266 Station. |
TCP/IP AT commands for ESP8266
| Command | Description |
| AT+CIPSTATUS | Gets the connection status |
| AT+CIPDOMAIN | DNS function |
| AT+CIPSTART | Establishes TCP connection, UDP transmission or SSL connection |
| AT+CIPSSLSIZE | Sets the size of SSL buffer |
| AT+CIPSEND | Sends data |
| AT+CIPSENDEX | Sends data when length of data is <length>, or when \0 appears in the data |
| AT+CIPSENDBUF | Writes data into TCP-send-buffer |
| AT+CIPBUFRESET | Resets the segment ID count |
| AT+CIPBUFSTATUS | Checks the status of TCP-send-buffer |
| AT+CIPCHECKSEQ | Checks if a specific segment is sent or not |
| AT+CIPCLOSE | Closes TCP/UDP/SSL connection |
| AT+CIFSR | Gets the local IP address |
| AT+CIPMUX | Configures the multiple connections mode |
| AT+CIPSERVER | Deletes/Creates a TCP server |
| AT+CIPMODE | Configures the transmission mode |
| AT+SAVETRANSLINK | Saves the transparent transmission link in the flash |
| AT+CIPSTO | Sets timeout when ESP8266 runs as TCP server |
| AT+PING | Ping packets |
| AT+CIUPDATE | Upgrades the software through network |
| AT+CIPDINFO | Shows remote IP and remote port with +IPD |
| AT+CIPSNTPCFG | Configures the time domain and SNTP server. |
| AT+CIPSNTPTIME | Queries the SNTP time. |
| AT+CIPDNS_CUR | Sets user-defined DNS servers; configuration not saved in the flash |
| AT+CIPDNS_DEF | Sets user-defined DNS servers; configuration saved in the flash |
Direct flashing/programming of ESP is recommended to get maximum benefits of powerful low cose WiFi Module. It uses same Arduino IDE and its C commands.