tmk_core/tool/mbed/mbed-sdk/libraries/mbed/api/AnalogOut.h

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2013 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #ifndef MBED_ANALOGOUT_H
  17 #define MBED_ANALOGOUT_H
  18
  19 #include "platform.h"
  20
  21 #if DEVICE_ANALOGOUT
  22
  23 #include "analogout_api.h"
  24
  25 namespace mbed {
  26
  27 /** An analog output, used for setting the voltage on a pin
  28  *
  29  * Example:
  30  * @code
  31  * // Make a sawtooth output
  32  *
  33  * #include "mbed.h"
  34  *
  35  * AnalogOut tri(p18);
  36  * int main() {
  37  *     while(1) {
  38  *         tri = tri + 0.01;
  39  *         wait_us(1);
  40  *         if(tri == 1) {
  41  *             tri = 0;
  42  *         }
  43  *     }
  44  * }
  45  * @endcode
  46  */
  47 class AnalogOut {
  48
  49 public:
  50
  51     /** Create an AnalogOut connected to the specified pin
  52      *
  53      *  @param AnalogOut pin to connect to (18)
  54      */
  55     AnalogOut(PinName pin) {
  56         analogout_init(&_dac, pin);
  57     }
  58
  59     /** Set the output voltage, specified as a percentage (float)
  60      *
  61      *  @param value A floating-point value representing the output voltage,
  62      *    specified as a percentage. The value should lie between
  63      *    0.0f (representing 0v / 0%) and 1.0f (representing 3.3v / 100%).
  64      *    Values outside this range will be saturated to 0.0f or 1.0f.
  65      */
  66     void write(float value) {
  67         analogout_write(&_dac, value);
  68     }
  69
  70     /** Set the output voltage, represented as an unsigned short in the range [0x0, 0xFFFF]
  71      *
  72      *  @param value 16-bit unsigned short representing the output voltage,
  73      *            normalised to a 16-bit value (0x0000 = 0v, 0xFFFF = 3.3v)
  74      */
  75     void write_u16(unsigned short value) {
  76         analogout_write_u16(&_dac, value);
  77     }
  78
  79     /** Return the current output voltage setting, measured as a percentage (float)
  80      *
  81      *  @returns
  82      *    A floating-point value representing the current voltage being output on the pin,
  83      *    measured as a percentage. The returned value will lie between
  84      *    0.0f (representing 0v / 0%) and 1.0f (representing 3.3v / 100%).
  85      *
  86      *  @note
  87      *    This value may not match exactly the value set by a previous write().
  88      */
  89     float read() {
  90         return analogout_read(&_dac);
  91     }
  92
  93 #ifdef MBED_OPERATORS
  94     /** An operator shorthand for write()
  95      */
  96     AnalogOut& operator= (float percent) {
  97         write(percent);
  98         return *this;
  99     }
 100
 101     AnalogOut& operator= (AnalogOut& rhs) {
 102         write(rhs.read());
 103         return *this;
 104     }
 105
 106     /** An operator shorthand for read()
 107      */
 108     operator float() {
 109         return read();
 110     }
 111 #endif
 112
 113 protected:
 114     dac_t _dac;
 115 };
 116
 117 } // namespace mbed
 118
 119 #endif
 120
 121 #endif