Diff: FastPWM.h

Revision:

0:16be67f4d9ac

diff -r 000000000000 -r 16be67f4d9ac FastPWM.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FastPWM.h	Tue Sep 19 16:52:01 2017 +0000
@@ -0,0 +1,150 @@
+/*
+    .---.           _....._
+   /  p  `\     .-""`:     :`"-.
+   |__   - |  ,'     .     '    ',
+    ._>    \ /:      :     ;      :,
+     '-.    '\`.     .     :     '  \
+        `.   | .'._.' '._.' '._.'.  |
+          `;-\.   :     :     '   '/,__,
+          .-'`'._ '     .     : _.'.__.'
+         ((((-'/ `";--..:..--;"` \
+             .'   /           \   \
+       jgs  ((((-'           ((((-'
+       
+Yeah ASCII art turtle more fun than copyright stuff
+*/
+
+
+#include "mbed.h"
+
+#ifndef FASTPWM_H
+#define FASTPWM_H
+
+/** Library that allows faster and/or higher resolution PWM output
+  *
+  * Library can directly replace standard mbed PWM library.
+  *
+  * Contrary to the default mbed library, this library takes doubles instead of floats. The compiler will autocast if needed,
+  * but do take into account it is done for a reason, your accuracy will otherwise be limitted by the floating point precision.
+  */
+class FastPWM : public PwmOut {
+public:
+    /**
+    * Create a FastPWM object connected to the specified pin
+    *
+    * @param pin - PWM pin to connect to
+    * @param prescaler - Clock prescaler, -1 is dynamic (default), 0 is bit random, everything else normal
+    */
+    FastPWM(PinName pin, int prescaler = -1);
+    ~FastPWM(); 
+    
+    /**
+    * Set the PWM period, specified in seconds (double), keeping the pulsewidth the same.
+    */
+    void period(double seconds);
+    
+    /**
+    * Set the PWM period, specified in milli-seconds (int), keeping the pulsewidth the same.
+    */
+    void period_ms(int ms);
+    
+    /**
+    * Set the PWM period, specified in micro-seconds (int), keeping the pulsewidth the same.
+    */
+    void period_us(int us);
+    
+    /**
+    * Set the PWM period, specified in micro-seconds (double), keeping the pulsewidth the same.
+    */
+    void period_us(double us);
+    
+    /**
+    * Set the PWM period, specified in clock ticks, keeping _pulse width_ the same.
+    *
+    * This function can be used if low overhead is required. Do take into account the result is
+    * board (clock frequency) dependent, and this does not keep an equal duty cycle!
+    */
+    void period_ticks(uint32_t ticks);
+    
+    /**
+    * Set the PWM pulsewidth, specified in seconds (double), keeping the period the same.
+    */
+    void pulsewidth(double seconds);
+    
+    /**
+    * Set the PWM pulsewidth, specified in milli-seconds (int), keeping the period the same.
+    */
+    void pulsewidth_ms(int ms);
+    
+    /**
+    * Set the PWM pulsewidth, specified in micro-seconds (int), keeping the period the same.
+    */
+    void pulsewidth_us(int us);
+    
+    /**
+    * Set the PWM pulsewidth, specified in micro-seconds (double), keeping the period the same.
+    */
+    void pulsewidth_us(double us);
+    
+    /**
+    * Set the PWM period, specified in clock ticks, keeping the period the same.
+    *
+    * This function can be used if low overhead is required. Do take into account the result is
+    * board (clock frequency) dependent!
+    */
+    void pulsewidth_ticks(uint32_t ticks);
+    
+    /**
+    * Set the ouput duty-cycle, specified as a percentage (double)
+    *
+    * @param duty - A double value representing the output duty-cycle, specified as a percentage.  The value should lie between 0.0 (representing on 0%) and 1.0 (representing on 100%).
+    */
+    void write(double duty);
+    
+    /**
+    * Return the ouput duty-cycle, specified as a percentage (double)
+    *
+    * @param return - A double value representing the output duty-cycle, specified as a percentage.
+    */
+    double read( void );
+    
+    /**
+    * An operator shorthand for write()
+    */
+    FastPWM& operator= (double value);
+    
+    /**
+    * An operator shorthand for read()
+    */
+    operator double();
+    
+    /**
+    * Set the PWM prescaler
+    *
+    * The period of all PWM pins on the same PWM unit have to be reset after using this!
+    *
+    * @param value - The required prescaler. Special values: 0 = lock current prescaler, -1 = use dynamic prescaler
+    * @param return - The prescaler which was set (can differ from requested prescaler if not possible)
+    */
+    int prescaler(int value);
+    
+private:
+    void initFastPWM(void);
+    
+    uint32_t setPrescaler( uint32_t reqScale );
+    int calcPrescaler(uint64_t clocks);
+    uint32_t getPeriod( void );
+    
+    void updateTicks( uint32_t prescaler );
+    uint32_t bits;
+    
+    double _duty;
+    
+    double dticks, dticks_us;
+    int iticks_ms, iticks_us;
+    
+    bool dynamicPrescaler;
+    
+    void *fast_obj;
+};
+#endif
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