DigitalOut.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 #ifndef MBED_DIGITALOUT_H
00017 #define MBED_DIGITALOUT_H
00018 
00019 #include "platform.h"
00020 #include "gpio_api.h"
00021 #include "critical.h"
00022 
00023 namespace mbed {
00024 
00025 /** A digital output, used for setting the state of a pin
00026  *
00027  * @Note Synchronization level: Interrupt safe
00028  *
00029  * Example:
00030  * @code
00031  * // Toggle a LED
00032  * #include "mbed.h"
00033  *
00034  * DigitalOut led(LED1);
00035  *
00036  * int main() {
00037  *     while(1) {
00038  *         led = !led;
00039  *         wait(0.2);
00040  *     }
00041  * }
00042  * @endcode
00043  */
00044 class DigitalOut {
00045 
00046 public:
00047     /** Create a DigitalOut connected to the specified pin
00048      *
00049      *  @param pin DigitalOut pin to connect to
00050      */
00051     DigitalOut(PinName pin) : gpio() {
00052         // No lock needed in the constructor
00053         gpio_init_out(&gpio, pin);
00054     }
00055 
00056     /** Create a DigitalOut connected to the specified pin
00057      *
00058      *  @param pin DigitalOut pin to connect to
00059      *  @param value the initial pin value
00060      */
00061     DigitalOut(PinName pin, int value) : gpio() {
00062         // No lock needed in the constructor
00063         gpio_init_out_ex(&gpio, pin, value);
00064     }
00065 
00066     /** Set the output, specified as 0 or 1 (int)
00067      *
00068      *  @param value An integer specifying the pin output value,
00069      *      0 for logical 0, 1 (or any other non-zero value) for logical 1
00070      */
00071     void write(int value) {
00072         // Thread safe / atomic HAL call
00073         gpio_write(&gpio, value);
00074     }
00075 
00076     /** Return the output setting, represented as 0 or 1 (int)
00077      *
00078      *  @returns
00079      *    an integer representing the output setting of the pin,
00080      *    0 for logical 0, 1 for logical 1
00081      */
00082     int read() {
00083         // Thread safe / atomic HAL call
00084         return gpio_read(&gpio);
00085     }
00086 
00087     /** Return the output setting, represented as 0 or 1 (int)
00088      *
00089      *  @returns
00090      *    Non zero value if pin is connected to uc GPIO
00091      *    0 if gpio object was initialized with NC
00092      */
00093     int is_connected() {
00094         // Thread safe / atomic HAL call
00095         return gpio_is_connected(&gpio);
00096     }
00097 
00098     /** A shorthand for write()
00099      */
00100     DigitalOut& operator= (int value) {
00101         // Underlying write is thread safe
00102         write(value);
00103         return *this;
00104     }
00105 
00106     DigitalOut& operator= (DigitalOut& rhs) {
00107         core_util_critical_section_enter();
00108         write(rhs.read());
00109         core_util_critical_section_exit();
00110         return *this;
00111     }
00112 
00113     /** A shorthand for read()
00114      */
00115     operator int() {
00116         // Underlying call is thread safe
00117         return read();
00118     }
00119 
00120 protected:
00121     gpio_t gpio;
00122 };
00123 
00124 } // namespace mbed
00125 
00126 #endif