Thanks to Zoltan Hudak publish the way to use STM32F103c8t6 on mbed. Now, this example can let you use it with a encoder.

Dependencies:   QEI mbed-STM32F103C8T6 mbed

Fork of STM32F103C8T6_Hello by Zoltan Hudak

Revision:
3:c6a589f444b9
Parent:
1:1dd12d8c840d
Child:
4:a81f44fc487e
--- a/main.cpp	Sat Jul 02 07:33:59 2016 +0000
+++ b/main.cpp	Sat Jul 02 07:51:56 2016 +0000
@@ -5,9 +5,11 @@
 
 int main() {
     while(1) {
-        myled = 1; // LED is ON
+        // The on-board LED is connected to pin PC_13 and, via a resistor, to +3V3. 
+        // So to turn the LED on or off we have to set it to 0 or 1 respectively
+        myled = 0; // turn the LED on
         wait(0.2); // 200 ms
-        myled = 0; // LED is OFF
+        myled = 1; // turn the LED off
         wait(1.0); // 1 sec
     }
 }