BusOut.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_BUSOUT_H
00017 #define MBED_BUSOUT_H
00018 
00019 #include "DigitalOut.h"
00020 #include "PlatformMutex.h"
00021 
00022 namespace mbed {
00023 
00024 /** A digital output bus, used for setting the state of a collection of pins
00025  */
00026 class BusOut {
00027 
00028 public:
00029 
00030     /** Create an BusOut, connected to the specified pins
00031      *
00032      *  @param p<n> DigitalOut pin to connect to bus bit <n> (p5-p30, NC)
00033      *
00034      *  @Note Synchronization level: Thread safe
00035      *
00036      *  @note
00037      *  It is only required to specify as many pin variables as is required
00038      *  for the bus; the rest will default to NC (not connected)
00039      */
00040     BusOut(PinName p0, PinName p1 = NC, PinName p2 = NC, PinName p3 = NC,
00041            PinName p4 = NC, PinName p5 = NC, PinName p6 = NC, PinName p7 = NC,
00042            PinName p8 = NC, PinName p9 = NC, PinName p10 = NC, PinName p11 = NC,
00043            PinName p12 = NC, PinName p13 = NC, PinName p14 = NC, PinName p15 = NC);
00044 
00045     BusOut(PinName pins[16]);
00046 
00047     virtual ~BusOut();
00048 
00049     /** Write the value to the output bus
00050      *
00051      *  @param value An integer specifying a bit to write for every corresponding DigitalOut pin
00052      */
00053     void write(int value);
00054 
00055     /** Read the value currently output on the bus
00056      *
00057      *  @returns
00058      *    An integer with each bit corresponding to associated DigitalOut pin setting
00059      */
00060     int read();
00061 
00062     /** Binary mask of bus pins connected to actual pins (not NC pins)
00063      *  If bus pin is in NC state make corresponding bit will be cleared (set to 0), else bit will be set to 1
00064      *
00065      *  @returns
00066      *    Binary mask of connected pins
00067      */
00068     int mask() {
00069         // No lock needed since _nc_mask is not modified outside the constructor
00070         return _nc_mask;
00071     }
00072 
00073     /** A shorthand for write()
00074      */
00075     BusOut& operator= (int v);
00076     BusOut& operator= (BusOut& rhs);
00077 
00078     /** Access to particular bit in random-iterator fashion
00079      */
00080     DigitalOut& operator[] (int index);
00081 
00082     /** A shorthand for read()
00083      */
00084     operator int();
00085 
00086 protected:
00087     virtual void lock();
00088     virtual void unlock();
00089     DigitalOut* _pin[16];
00090 
00091     /** Mask of bus's NC pins
00092      * If bit[n] is set to 1 - pin is connected
00093      * if bit[n] is cleared - pin is not connected (NC)
00094      */
00095     int _nc_mask;
00096 
00097     PlatformMutex _mutex;
00098 
00099    /* disallow copy constructor and assignment operators */
00100 private:
00101     BusOut(const BusOut&);
00102     BusOut & operator = (const BusOut&);
00103 };
00104 
00105 } // namespace mbed
00106 
00107 #endif