ESP8266 モジュールの AT コマンドに SSL クライアント機能を追加する

In the example of \esp_iot_sdk\examples\at\user\user_main.c, 
ways are delivered on how to implement a self-defined AT Command,
 AT+TEST”.
The structure, at_funcationType, is used to define four types of
a command, e.g., “AT+TEST”. 

"at_testCmd" is a testing command and it’s formatted as AT+TEST=?.
In the example of AT, the registered callback is “at_testCmdTest”; 
the testing demand could be designed as the value range of the
return parameter. If registered as NULL, there will be no testing
command.

"at_queryCmd" is a query command and it’s formatted as AT+TEST?.
In the example of AT, the registered callback is “at_queryCmdTest” ; 
the query command could be designed as returning the current value. 
If registered as NULL, there will be no query command.

"at_setupCmd" is a setup command and it’s formatted as
AT+TEST=parameter1,parameter2,........ In the example of AT, 
the registered callback is "at_setupCmdTest"; 
the setup command could be designed as the value of the parameter; 
if registered as NULL, there will be no setup command.

"at_exeCmd" is an execution command and it’s formatted as AT+TEST. 
In the example of AT, the registered callback is “at_exeCmdTest”; 
if registered as NULL, there will be no execution command.

ESP-WROOM-02 出荷時の標準ファーム（AT コマンドセット）は以下のバイナリから構成されます。

bin/boot_v1.2.bin ---- ブートローダ
bin/at/user1.1024.new.2.bin ---- AT コマンドプログラム本体
bin/blank.bin ---- 領域初期化用　中身は 0xFF * 4096バイト
bin/esp_init_data_default.bin --- "Stores default RF parameter values"





※「user1.1024.new.2.bin」の「1024」は 1024KB（8Mbit）容量のフラッシュメモリ使用を想定してビルドされたバイナリであることを意味する。