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PwmOut Class Reference
Public Member Functions | Static Public Member Functions

PwmOut Class Reference

A pulse-width modulation digital output. More...

#include <PwmOut.h>

Inherits mbed::Base.

Public Member Functions

 PwmOut (PinName pin, const char *name=NULL)
 Create a PwmOut connected to the specified pin.
void write (float value)
 Set the ouput duty-cycle, specified as a percentage (float)
float read ()
 Return the current output duty-cycle setting, measured as a percentage (float)
void period (float seconds)
 Set the PWM period, specified in seconds (float), keeping the duty cycle the same.
void period_ms (int ms)
 Set the PWM period, specified in milli-seconds (int), keeping the duty cycle the same.
void period_us (int us)
 Set the PWM period, specified in micro-seconds (int), keeping the duty cycle the same.
void pulsewidth (float seconds)
 Set the PWM pulsewidth, specified in seconds (float), keeping the period the same.
void pulsewidth_ms (int ms)
 Set the PWM pulsewidth, specified in milli-seconds (int), keeping the period the same.
void pulsewidth_us (int us)
 Set the PWM pulsewidth, specified in micro-seconds (int), keeping the period the same.
PwmOut & operator= (float value)
 A operator shorthand for write()
 operator float ()
 An operator shorthand for read()
virtual struct rpc_method * get_rpc_methods ()
 Returns a pointer to an array describing the rpc methods supported by this object, terminated by either RPC_METHOD_END or RPC_METHOD_SUPER(Superclass).
void register_object (const char *name)
 Registers this object with the given name, so that it can be looked up with lookup.
const char * name ()
 Returns the name of the object.
virtual bool rpc (const char *method, const char *arguments, char *result)
 Call the given method with the given arguments, and write the result into the string pointed to by result.

Static Public Member Functions

static bool rpc (const char *name, const char *method, const char *arguments, char *result)
 Use the lookup function to lookup an object and, if successful, call its rpc method.
static Base * lookup (const char *name, unsigned int len)
 Lookup and return the object that has the given name.
template<class C >
static void add_rpc_class ()
 Add the class to the list of classes which can have static methods called via rpc (the static methods which can be called are defined by that class' get_rpc_class() static method).

Detailed Description

A pulse-width modulation digital output.

Example 

 // Fade a led on.
 #include "mbed.h"

 PwmOut led(LED1);
 
 int main() {
     while(1) {
         led = led + 0.01;
         wait(0.2);
         if(led == 1.0) {
             led = 0;
         }
     }
 }
Note:
On the LPC1768 and LPC2368, the PWMs all share the same period - if you change the period for one, you change it for all. Although routines that change the period maintain the duty cycle for its PWM, all other PWMs will require their duty cycle to be refreshed.

Definition at line 46 of file PwmOut.h.

Constructor & Destructor Documentation

PwmOut ( PinName  pin,
const char *  name = NULL 
)

Create a PwmOut connected to the specified pin.

Parameters:
pinPwmOut pin to connect to

Member Function Documentation

static void add_rpc_class (  ) [static, inherited]

Add the class to the list of classes which can have static methods called via rpc (the static methods which can be called are defined by that class' get_rpc_class() static method).

Definition at line 143 of file Base.h.

virtual struct rpc_method* get_rpc_methods (  ) [read, virtual]

Returns a pointer to an array describing the rpc methods supported by this object, terminated by either RPC_METHOD_END or RPC_METHOD_SUPER(Superclass).

Example 

 class Example : public Base {
     int foo(int a, int b) { return a + b; }
     virtual const struct rpc_method *get_rpc_methods() {
         static const rpc_method rpc_methods[] = {
             { "foo", generic_caller<int, Example, int, int, &Example::foo> },
             RPC_METHOD_SUPER(Base)
         };
         return rpc_methods;
     }
 };

Reimplemented from Base.

static Base* lookup ( const char *  name,
unsigned int  len 
) [static, inherited]

Lookup and return the object that has the given name.

Parameters:
namethe name to lookup.
lenthe length of name.
const char* name (  ) [inherited]

Returns the name of the object.

Returns:
The name of the object, or NULL if it has no name.
operator float (  )

An operator shorthand for read()

PwmOut& operator= ( float  value )

A operator shorthand for write()

void period ( float  seconds )

Set the PWM period, specified in seconds (float), keeping the duty cycle the same.

Note:
The resolution is currently in microseconds; periods smaller than this will be set to zero.
void period_ms ( int  ms )

Set the PWM period, specified in milli-seconds (int), keeping the duty cycle the same.

void period_us ( int  us )

Set the PWM period, specified in micro-seconds (int), keeping the duty cycle the same.

void pulsewidth ( float  seconds )

Set the PWM pulsewidth, specified in seconds (float), keeping the period the same.

void pulsewidth_ms ( int  ms )

Set the PWM pulsewidth, specified in milli-seconds (int), keeping the period the same.

void pulsewidth_us ( int  us )

Set the PWM pulsewidth, specified in micro-seconds (int), keeping the period the same.

float read (  )

Return the current output duty-cycle setting, measured as a percentage (float)

Returns:
A floating-point value representing the current duty-cycle being output on the pin, measured as a percentage. The returned value will lie between 0.0f (representing on 0%) and 1.0f (representing on 100%).
Note:
This value may not match exactly the value set by a previous <write>.
void register_object ( const char *  name ) [inherited]

Registers this object with the given name, so that it can be looked up with lookup.

If this object has already been registered, then this just changes the name.

Parameters:
nameThe name to give the object. If NULL we do nothing.
virtual bool rpc ( const char *  method,
const char *  arguments,
char *  result 
) [virtual, inherited]

Call the given method with the given arguments, and write the result into the string pointed to by result.

The default implementation calls rpc_methods to determine the supported methods.

Parameters:
methodThe name of the method to call.
argumentsA list of arguments separated by spaces.
resultA pointer to a string to write the result into. May be NULL, in which case nothing is written.
Returns:
true if method corresponds to a valid rpc method, or false otherwise.
static bool rpc ( const char *  name,
const char *  method,
const char *  arguments,
char *  result 
) [static, inherited]

Use the lookup function to lookup an object and, if successful, call its rpc method.

Returns:
false if name does not correspond to an object, otherwise the return value of the call to the object's rpc method.
void write ( float  value )

Set the ouput duty-cycle, specified as a percentage (float)

Parameters:
valueA floating-point value representing the output duty-cycle, specified as a percentage. The value should lie between 0.0f (representing on 0%) and 1.0f (representing on 100%). Values outside this range will be saturated to 0.0f or 1.0f.
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