AnalogOut.h

00001 /* mbed Microcontroller Library - AnalogOut
00002  * Copyright (c) 2006-2011 ARM Limited. All rights reserved.
00003  */ 
00004  
00005 #ifndef MBED_ANALOGOUT_H
00006 #define MBED_ANALOGOUT_H
00007 
00008 #include "device.h"
00009 
00010 #if DEVICE_ANALOGOUT
00011 
00012 #include "platform.h"
00013 #include "PinNames.h"
00014 #include "PeripheralNames.h"
00015 #include "Base.h"
00016 
00017 namespace mbed {
00018 
00019 /** An analog output, used for setting the voltage on a pin
00020  *
00021  * Example:
00022  * @code
00023  * // Make a sawtooth output
00024  *  
00025  * #include "mbed.h"
00026  *  
00027  * AnalogOut tri(p18);
00028  * int main() {
00029  *     while(1) {
00030  *         tri = tri + 0.01;
00031  *         wait_us(1);
00032  *         if(tri == 1) {
00033  *             tri = 0;
00034  *         }
00035  *     }
00036  * }
00037  * @endcode
00038  */
00039 class AnalogOut : public Base {
00040 
00041 public:
00042 
00043     /** Create an AnalogOut connected to the specified pin
00044      * 
00045      *  @param AnalogOut pin to connect to (18)
00046      */
00047     AnalogOut(PinName pin, const char *name = NULL);
00048     
00049     /** Set the output voltage, specified as a percentage (float)
00050      *
00051      *  @param value A floating-point value representing the output voltage, 
00052      *    specified as a percentage. The value should lie between
00053      *    0.0f (representing 0v / 0%) and 1.0f (representing 3.3v / 100%).
00054      *    Values outside this range will be saturated to 0.0f or 1.0f.     
00055      */
00056     void write(float value);
00057     
00058     /** Set the output voltage, represented as an unsigned short in the range [0x0, 0xFFFF]
00059      *
00060      *  @param value 16-bit unsigned short representing the output voltage,
00061      *    normalised to a 16-bit value (0x0000 = 0v, 0xFFFF = 3.3v)
00062      */
00063     void write_u16(unsigned short value);
00064 
00065     /** Return the current output voltage setting, measured as a percentage (float)
00066      *
00067      *  @returns
00068      *    A floating-point value representing the current voltage being output on the pin, 
00069      *    measured as a percentage. The returned value will lie between
00070      *    0.0f (representing 0v / 0%) and 1.0f (representing 3.3v / 100%).
00071      *
00072      *  @note
00073      *    This value may not match exactly the value set by a previous write().
00074      */    
00075     float read();
00076 
00077 
00078 #ifdef MBED_OPERATORS
00079     /** An operator shorthand for write()
00080      */
00081     AnalogOut& operator= (float percent);
00082     AnalogOut& operator= (AnalogOut& rhs);
00083 
00084     /** An operator shorthand for read()
00085      */    
00086     operator float();
00087 #endif
00088 
00089 #ifdef MBED_RPC
00090     virtual const struct rpc_method *get_rpc_methods();
00091     static struct rpc_class *get_rpc_class();
00092 #endif
00093 
00094 protected:
00095 
00096     DACName _dac;
00097 
00098 };
00099 
00100 } // namespace mbed
00101 
00102 #endif
00103 
00104 #endif