Free and open (as much as possible) integrated SDK for ESP8266/ESP8285 chips
root@host:~# sudo apt-get install make unrar-free autoconf automake libtool gcc g++ gperf \
flex bison texinfo gawk ncurses-dev libexpat-dev python-dev python python-serial \
sed git unzip bash help2man wget bzip2
root@host:~# sudo apt-get install libtool-bin
root@host:~$ git clone --recursive https://github.com/pfalcon/esp-open-sdk.git
root@host:~$ cd esp-open-sdk/
root@host:~$ make
root@host:~$ export PATH=/home/xe1gyq/NodeMcu/esp-open-sdk/xtensa-lx106-elf/bin:$PATH
$ make clean
$ git pull
$ git submodule sync
$ git submodule update