Program for a STM32F4 board in CoIDE transmit voltage to a PIN HELP

[victorrr]

Hello,
I want to program a STM32F4 board in CoIDE so it can transmit a voltage to a pin and then stop for a while and then again transmit voltage to the pin. I want to program the board so it can send periodically voltage to a ultrasound transducer. It has to do something like this:

http://upload.wikimedia.org/wikipedi...le_general.png

Can someone help me please? I have programmed easy things like turning on the leds but i'm stuck for doing this.

Thank you very much

 

[Harald Kapp]

Can someone help me please? I have programmed easy things like turning on the leds but i'm stuck for doing this.

Where's the difference in turning on and off an LED and using the same signal to control an ultrasound transducer? Just hook up the transducer to the portpin instead of the LED.