Notice: 
AT firmware becomes larger since it supports more functions. So, we provide two examples here:

* Normal AT, ESP8266_NONOS_SDK/examples/at, supports 2MB or larger flash, uses mbedTLS lib, the default AT.
* Nano AT, ESP8266_NONOS_SDK/examples/at_nano, supports 1MB flash, uses SSL lib which supports less cipher suites.
It is suggested to use normal AT, if your flash size is 2MB or larger.

1compile options

(1) COMPILE
    Possible value: gcc
    Default value: 
    If not set, use xt-xcc by default.

(2) BOOT
    Possible value: none/old/new
      none: no need boot
      old: use boot_v1.1
      new: use boot_v1.2+
    Default value: none

(3) APP
    Possible value: 0/1/2
      0: original mode, generate eagle.app.v6.flash.bin and eagle.app.v6.irom0text.bin
      1: generate user1
      2: generate user2
    Default value: 0

(3) SPI_SPEED
    Possible value: 20/26.7/40/80
    Default value: 40

(4) SPI_MODE
    Possible value: QIO/QOUT/DIO/DOUT
    Default value: QIO

(4) SPI_SIZE
    Possible value: 0/2/3/4/5/6
    Default value: 0

For example:
    make COMPILE=gcc BOOT=new APP=1 SPI_SPEED=40 SPI_MODE=QIO SPI_SIZE_MAP=0

2You can also use gen_misc to make and generate specific bin you needed.
    Linux: ./gen_misc.sh
    Windows: gen_misc.bat
    Follow the tips and steps.
