ESP8266 AT Release v2.2.2.0

The documentation for ESP-AT v2.2.2.0 is available at https://docs.espressif.com/projects/esp-at/en/release-v2.2.0.0_esp8266/. This release is a minor update to ESP-AT v2.2.1.0.

Breaking Changes Since Release v2.2.1.0

Added the AT+USERWKMCUCFG and AT+USERMCUSLEEP commands to wake up MCU.
Added the AT+CIPSSLCCIPHER command to specify ssl cipher suite.
Added AT+CIPSTATE command to query connection state.
Added fallback DNS server. AT has two DNS servers ("208.67.222.222" and "8.8.8.8") by default.
Added the AT+MQTTLONGCLIENTID command to set MQTT client ID.
Added the AT+MQTTLONGUSERNAME command to set MQTT username.
Added the AT+MQTTLONGPASSWORD command to set MQTT password.
AT+WEBSERVER: Wi-Fi provisioning supports the special character in SSID and password.

Fixed an issue where AT+CWJAP occasionally returned an incorrect reason code.
Fixed an issue where AT+CWSTATE occasionally returned an incorrect state.
Fixed a potential crash when the lSSID length was exactly 32 bytes or the password length was 64 bytes.
Fixed an issue where AT+CWLAP occasionally returned an ERROR.
Fixed an auto-connection issue with WPA2 Enterprise AP. Users should always use AT+CWJEAP to connect to a WPA2 Enterprise AP.
Fixed an issue where the +CWJAP error code might be printed before the "WIFI DISCONNECT" message.

Fixed an issue where the AT+CIPDNS query command returned an incorrect configuration.
Fixed an issue where AT+CIPSERVER=0,1 did not correctly close clients connected to the ESP TCP server.
Fixed an issue where setting AT+CIPSERVER=5 returned "Have 255 Connections" sometimes.
Fixed an issue where AT+CIPTCPOPT send timeout parameter failed to work sometimes.
Fixed an issue with active TCP data writes in passive mode.
Fixed an occasional crash in passthrough mode caused by a socket close.
Fixed +IPD report loss when the TCP connection was reopened while AT was acting as a server.
Fixed an occasional failure when AT+CIPSERVERMAXCONN=5 was set.
Fixed an issue where AT+CIPSTO did not reset the timer after sending data.
Fixed an ssl connection issue where the connection was dropped after receiving data when AT+CIPRECVMODE=1 was used.
Updated the "+IPD" command to report actual ssl available bytes whenever possible, except when TCP buffers data but SSL does not.
Fixed a potential illegal assignment issue with the AT+CIPTCPOPT command in multiple connections.
Fixed an issue where AT+CIPTCPOPT did not work when ESP-AT operated as a server.
Fixed an issue where AT+CIPSTART could not establish multiple UDP transmissions on the same port.
Fixed an occasional disconnection issue when the link state changed.
Corrected an invalid maximum number of tcp retransmission.
Fixed an issue where the maximum parameter length for AT+CIPSSLCCN and AT+CIPSSLCSNI could not be set to 64 bytes.

Removed extra space in AT+HTTPCLIENT HEAD response.
Fixed an issue where AT+HTTPCPOST response returned the wrong command name when additional POST data was appended.

Fixed an issue of high power consumption after power-on when AT+CWMODE=0 was set.
Fixed a potential issue where uart data was blocked in the RX ring buffer.
Fixed several potential busy p... issues occurring occasionally.
Fixed a problem where GPIO15 did not function correctly in custom modules based on ESP8266.
Fixed an occasional system hang caused by a deadlock.
Fixed a crash occurring when invalid GPIO wake-up configurations were set.

Removed potential NVS writes at startup when dirty data was detected during NVS read operations.
Enhanced handling of multiple connections by ensuring all available bytes from one link are read before processing the next.
Added parameters validation for the AT+CIPTCPOPT command.