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:
6:d99931fc19c0
Parent:
5:3c3ef17a17a6
Child:
7:accb2c83a007
--- a/main.cpp	Tue Jul 05 18:21:02 2016 +0000
+++ b/main.cpp	Tue Jul 05 18:24:49 2016 +0000
@@ -1,11 +1,11 @@
 #include "stm32f103c8t6.h"
 #include "mbed.h"
 
-Serial      pc(USBTX, USBRX);
+Serial      pc(PA_2, PA_3);
 DigitalOut  myled(LED1);
 
 int main() {
-    configSysClock();   // selecting 72MHz High-speed External clock and 32MHz APB1 peripheral clock
+    configSysClock();   // selecting 72MHz High-speed External 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