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:
7:accb2c83a007
Parent:
6:d99931fc19c0
Child:
8:f1432e9af6c8
--- a/main.cpp	Tue Jul 05 18:24:49 2016 +0000
+++ b/main.cpp	Tue Jul 05 18:57:42 2016 +0000
@@ -5,14 +5,14 @@
 DigitalOut  myled(LED1);
 
 int main() {
-    configSysClock();   // selecting 72MHz High-speed External clock
+    confSysClock();     // Configuring system clock
     while(1) {
         // The on-board LED is connected, via a resistor, to +3.3V (not to GND). 
         // 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 = 1; // turn the LED off
-        wait(1.0); // 1 sec
+        myled = 0;      // turn the LED on
+        wait(0.2);      // 200 ms
+        myled = 1;      // turn the LED off
+        wait(1.0);      // 1 sec
         pc.printf("Blink\r\n");
     }
 }