Revision 0:c165325c9e3f, committed 2018-03-02

Comitter:

jdonnal

Date:

Fri Mar 02 16:52:58 2018 +0000

Child:

1:b17c9f1d9d5c

Commit message:

Initial Commit

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Tach.cpp	Fri Mar 02 16:52:58 2018 +0000
@@ -0,0 +1,38 @@
+ #include "Tach.h"
+ 
+ //64 counts per rev
+ 
+ Tach::Tach(PinName input, 
+            int pulsesPerRev): input_(input){
+    speed_       = 0.0;
+    pulsesPerRev_ = pulsesPerRev;
+    input_.mode(PullUp);
+    input_.rise(this, &Tach::update);
+    //input_.fall(this, &Tach::update);
+    timer_.start();
+    for(int i=0;i<NSAMP;i++){
+        speedBuffer_[i]=0.0;
+    }
+}
+int Tach::getCount(void){
+    return count_;
+}
+float Tach::getSpeed(void) {
+
+    float acc=0;
+    for(int i=0;i<NSAMP;i++){
+        acc+=speedBuffer_[i];
+    }
+    return acc/NSAMP;
+
+}
+
+void Tach::update(void) {
+    float speed;
+    static int i=0;
+    count_++;
+    speed =  1.0/(timer_.read()*pulsesPerRev_);
+    speedBuffer_[i%NSAMP]=speed;
+    i++;
+    timer_.reset();
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Tach.h	Fri Mar 02 16:52:58 2018 +0000
@@ -0,0 +1,75 @@
+
+/* Single Channel Encoder as Speedometer
+   John Donnal 2018
+*/
+
+#ifndef TACH_H
+#define TACH_H
+
+/**
+ * Includes
+ */
+#include "mbed.h"
+
+/**
+ * Defines
+ */
+#define NSAMP 3
+
+/**
+ * Tach Interface.
+ */
+class Tach {
+
+public:
+
+    /**
+     * Constructor.
+     *
+     * Tracks rising and falling edges with interrupts, provides
+     * rotations per second (Hz) output
+     *
+     * @param input mbed pin for input channel.
+     * @param pulsesPerRev Number of pulses in one revolution.
+     * @param encoding The encoding to use. Uses X2 encoding by default. X2
+     */
+    Tach(PinName input, int pulsesPerRev);
+
+    /**
+     * Read the state of the encoder.
+     *
+     * @return The current state of the encoder as a 2-bit number, where:
+     *         bit 1 = The reading from channel B
+     *         bit 2 = The reading from channel A
+     */
+    float getSpeed(void);
+    int getCount(void);
+   
+private:
+
+    /**
+     * Update the pulse count.
+     *
+     * Called on every rising/falling edge of input
+     *
+     * update current speed estimate
+     */
+    void update(void);
+
+    /**
+     * Called on every rising edge of channel index to update revolution
+     * count by one.
+     */
+    void index(void);
+
+    InterruptIn input_;
+    Timer timer_;
+    
+    int          pulsesPerRev_;
+    float        speed_;
+    int          count_;
+    int          dt_;
+    float        speedBuffer_[NSAMP];
+};
+
+#endif /* TACH_H */