It is based on https://developer.mbed.org/users/gregeric/code/Nucleo_Hello_Encoder/

Revision:
0:caf1d0bc4b90
Child:
2:4580c3869b7b
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rotary_encoder_base/rotary_encoder_base.cpp	Sat Feb 06 14:24:56 2016 +0000
@@ -0,0 +1,57 @@
+#include "rotary_encoder_base.hpp"
+#include "rotary_encoder.hpp"
+
+rotary_encoder_base::rotary_encoder_base(TIM_TypeDef* timer_type,
+                                        uint32_t encoder_mode,
+                                        size_t resolution) : rotary_encoder(resolution) {
+    TIM_Encoder_InitTypeDef encoder;
+    timer_handler_ = new TIM_HandleTypeDef;
+    
+    timer_handler_->Instance              = timer_type;
+    timer_handler_->Init.Period           = max_counts_;
+    timer_handler_->Init.CounterMode      = TIM_COUNTERMODE_UP;
+    timer_handler_->Init.Prescaler        = 0;
+    timer_handler_->Init.ClockDivision    = TIM_CLOCKDIVISION_DIV1;
+
+    encoder.EncoderMode = encoder_mode;
+
+    encoder.IC1Filter       = 0x0F;
+    encoder.IC1Polarity     = TIM_INPUTCHANNELPOLARITY_RISING;
+    encoder.IC1Prescaler    = TIM_ICPSC_DIV4;
+    encoder.IC1Selection    = TIM_ICSELECTION_DIRECTTI;
+
+    encoder.IC2Filter       = 0x0F;
+    encoder.IC2Polarity     = TIM_INPUTCHANNELPOLARITY_FALLING;
+    encoder.IC2Prescaler    = TIM_ICPSC_DIV4;
+    encoder.IC2Selection    = TIM_ICSELECTION_DIRECTTI;
+
+    if (HAL_TIM_Encoder_Init(timer_handler_, &encoder) != HAL_OK) {
+        error("couldn't init encoder\r\n");
+    }
+}
+
+int32_t rotary_encoder_base::get_counts() const {
+    int32_t counts = timer_handler_->Instance->CNT;
+    
+    if (counts > (max_counts_ >> 1)) {
+        return counts - max_counts_;
+    }
+    
+    return  counts;
+}
+
+void rotary_encoder_base::reset() {
+    timer_handler_->Instance->CNT = 0;
+}
+
+void rotary_encoder_base::start() {
+    if(HAL_TIM_Encoder_Start(timer_handler_, TIM_CHANNEL_1) != HAL_OK) {
+        error("couldn't start encoder\r\n");
+    }
+}
+
+void rotary_encoder_base::stop() {
+    if(HAL_TIM_Encoder_Stop(timer_handler_, TIM_CHANNEL_1) != HAL_OK) {
+        error("couldn't start encoder\r\n");
+    }
+}