Diff: FtEncoder.h

Revision:

1:9e595056c3da

Parent:

0:8cb1142a88d5

Child:

2:1bf9f7b6bf29

diff -r 8cb1142a88d5 -r 9e595056c3da FtEncoder.h
--- a/FtEncoder.h	Thu Mar 14 18:27:24 2013 +0000
+++ b/FtEncoder.h	Wed Mar 20 21:42:39 2013 +0000
@@ -8,34 +8,37 @@
 
 using namespace mbed;
 
-/// Simple Interface for the encoder of the red fischertechnik motors
+/// Simple Interface for the simple encoder of the red fischertechnik motors.
+/// The interface counts both, rising and falling edges, resulting in 150 counts per revolution.
+/// The interface also provides a speed measurement updated with each edge. 
 /// @note Connect the green wire to GND, the red one to +3.3V and the 
 /// black signal line to any of mbed numbered pins. Additionally connect the signal line
 /// via a pullup resitor to +3.3V. A 10K resistor works fine.
 /// 
 class FtEncoder
 {
-    static const float c_speedFactor = 1e6/75.0; // 1/(µs * 150/2) edges per revolution)
-    static const int c_nTmStmps = 1<<2;
+    static const float c_speedFactor = 1e6/75.0; /// 1/(µs * 150/2) edges per revolution)
+    static const int c_nTmStmps = 1<<2; /// size of ringbuffer: Has to be 2^x
 
     InterruptIn m_encIRQ;
     Timeout m_tmOut;
 
-    volatile unsigned int m_cnt;
-    unsigned int m_standStillTimeout;
-    volatile unsigned int m_cursor;
-    unsigned int m_timeStamps[c_nTmStmps];
-    bool m_ready;
+    volatile unsigned int m_cnt; /// edge counter
+    unsigned int m_standStillTimeout; 
+    volatile unsigned int m_cursor;  /// ringbuffer cursor
+    uint32_t m_timeStamps[c_nTmStmps]; /// ringbuffer of edge timestamps 
 
     FunctionPointer m_callBack;
 
     /// ISR called on rising and falling encoder edges
     void encoderISR();
+    /// ISR called on edge timeout i.e. standstill
+    void timeoutISR();
 
 public:
 
     /// create a simple interface to the encoder connected to the given pin
-    /// @param name of the pin the black encoder signl wire is connected to
+    /// @param name of the pin the black encoder signal wire is connected to
     /// @param standStillTimeout After this time [µs] without any encoder edge getSpeed() returns zero
     FtEncoder(PinName pwm, unsigned int standStillTimeout=50000);