DigitalIn.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_DIGITALIN_H
00017 #define MBED_DIGITALIN_H
00018 
00019 #include "platform.h"
00020 
00021 #include "gpio_api.h"
00022 #include "critical.h"
00023 
00024 namespace mbed {
00025 
00026 /** A digital input, used for reading the state of a pin
00027  *
00028  * @Note Synchronization level: Interrupt safe
00029  *
00030  * Example:
00031  * @code
00032  * // Flash an LED while a DigitalIn is true
00033  *
00034  * #include "mbed.h"
00035  *
00036  * DigitalIn enable(p5);
00037  * DigitalOut led(LED1);
00038  *
00039  * int main() {
00040  *     while(1) {
00041  *         if(enable) {
00042  *             led = !led;
00043  *         }
00044  *         wait(0.25);
00045  *     }
00046  * }
00047  * @endcode
00048  */
00049 class DigitalIn {
00050 
00051 public:
00052     /** Create a DigitalIn connected to the specified pin
00053      *
00054      *  @param pin DigitalIn pin to connect to
00055      */
00056     DigitalIn(PinName pin) : gpio() {
00057         // No lock needed in the constructor
00058         gpio_init_in(&gpio, pin);
00059     }
00060 
00061     /** Create a DigitalIn connected to the specified pin
00062      *
00063      *  @param pin DigitalIn pin to connect to
00064      *  @param mode the initial mode of the pin
00065      */
00066     DigitalIn(PinName pin, PinMode mode) : gpio() {
00067         // No lock needed in the constructor
00068         gpio_init_in_ex(&gpio, pin, mode);
00069     }
00070     /** Read the input, represented as 0 or 1 (int)
00071      *
00072      *  @returns
00073      *    An integer representing the state of the input pin,
00074      *    0 for logical 0, 1 for logical 1
00075      */
00076     int read() {
00077         // Thread safe / atomic HAL call
00078         return gpio_read(&gpio);
00079     }
00080 
00081     /** Set the input pin mode
00082      *
00083      *  @param mode PullUp, PullDown, PullNone, OpenDrain
00084      */
00085     void mode(PinMode pull) {
00086         core_util_critical_section_enter();
00087         gpio_mode(&gpio, pull);
00088         core_util_critical_section_exit();
00089     }
00090 
00091     /** Return the output setting, represented as 0 or 1 (int)
00092      *
00093      *  @returns
00094      *    Non zero value if pin is connected to uc GPIO
00095      *    0 if gpio object was initialized with NC
00096      */
00097     int is_connected() {
00098         // Thread safe / atomic HAL call
00099         return gpio_is_connected(&gpio);
00100     }
00101 
00102     /** An operator shorthand for read()
00103      */
00104     operator int() {
00105         // Underlying read is thread safe
00106         return read();
00107     }
00108 
00109 protected:
00110     gpio_t gpio;
00111 };
00112 
00113 } // namespace mbed
00114 
00115 #endif