Accessing 8bit and 16bit constants from ROM rather than RAM comes with a
performance cost, as these loads go through the load/store exception
vector. Any performance critical constants can be forced back into RAM
as RAM_CONST_ATTR.
The entry point has changed from call_user_start() to user_start_trampoline()
in order for the exception handler to be installed early enough.
The open source LWIP is broken, use espressif's liblwip.a.
Uses system_get_vdd33 instead of readvdd33.
The espressif's sdk0.9.6 beta1 (2015.02.15) release note
1、Optimize smartconfig to version v0.8;
2、Optimize AT to version 0.22.b1;
1>、Fixed bugs;
2>、Optimize the speed of transparent transmission;
3、Optimize boot to version 1.3(b3);
1>、Fix compatibility problem of dual flash ;
4、Solve problem of the large current in deep sleep;
5、Fixed problem “check mem fail”;
6、Fixed problem of UDP socket may stop listening broadcast packet after a long time running under some special router;
7、Fixed bug related to wifi_station_scan;
8、Other optimize to make the software more reliable;