I hope use it and enjoy.
I use Stm32f103c8 and Keil Compiler and Stm32CubeMX wizard.
Please Do This ...
1) Enable FreeRTOS or not.
2) Config your timer and Select Pwm channel and enable Update interrupt on CubeMX.On 72Mhz : Prescaler=17 , Counter Period = 255.
3) Select "General peripheral Initalizion as a pair of '.c/.h' file per peripheral" on project settings.
4) Config your DtmfConfig.h file.
5) Add Dtmf_CallBack() on Timer interrupt routin.
6) call Dtmf_Init() on your app.
7) use this function like Dtmf_Send() on your app. Example Dtmf_Send("1234aB",200,200);