Please use Sim800_v2.
I hope use it and enjoy.
GsmLib on Example maybe older version.Replace with new version.
I use Stm32f103C8 and Keil Compiler and Stm32CubeMX wizard.
Please Do This ...
1) Enable FreeRTOS
2) Config your usart and enable interrupt on CubeMX
3) 2 control Pin needed. (PowerKey>>>>output,open drain,default to SET) and (Power status>>>>input,pulldown)
PowerKey connect to Sim800 Power Key. PowerStatus connect to Sim800 output vcc 2.8V
4) Select "General peripheral Initalizion as a pair of '.c/.h' file per peripheral" on project settings.
5) Config your GsmConfig.h file.
6) Add Gsm_RxCallBack() on usart interrupt routin.
7) call Gsm_Init(osPriorityNormal) on your app.
8) Config your app on GsmUser.c.