ShiftReg.h

00001 /* mbed Shift Register Library, such as for NXP 74HC595
00002  * Copyright (c) 2012, YoongHM
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy
00005  * of this software and associated documentation files (the "Software"), to deal
00006  * in the Software without restriction, including without limitation the rights
00007  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008  * copies of the Software, and to permit persons to whom the Software is
00009  * furnished to do so, subject to the following conditions:
00010  *
00011  * The above copyright notice and this permission notice shall be included in
00012  * all copies or substantial portions of the Software.
00013  *
00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00017  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00020  * THE SOFTWARE.
00021  */
00022  
00023 #ifndef _SHIFTREG_H
00024 #define _SHIFTREG_H
00025 
00026 #include "mbed.h"
00027 
00028 /** A interface to drive shifter register as such 74HCT595
00029  *
00030  * @code
00031  * #include "mbed.h"
00032  * #include "ShiftReg.h"
00033  * 
00034  * ShiftReg   HC595(p21, p22, p23);
00035  * 
00036  * int main() {
00037  *     // clear shift and store registers initially
00038  *     HC595.ShiftByte(0x00, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00039  *     
00040  *     while(1) {
00041  *         // Demostrate to shift in bit by bit
00042  *         HC595.ShiftBit(1); HC595.Latch(); wait(0.2);
00043  *         for (int i = 0; i < 8; i++) {
00044  *             HC595.ShiftBit(0); HC595.Latch(); wait(0.2);
00045  *         }
00046 
00047  *         // Demostrate to shift in byte-by-byte
00048  *      // HC595.ShiftByte(0x80, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00049  *         HC595.ShiftByte(0x40, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00050  *         HC595.ShiftByte(0x20, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00051  *         HC595.ShiftByte(0x10, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00052  *         HC595.ShiftByte(0x08, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00053  *         HC595.ShiftByte(0x04, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00054  *         HC595.ShiftByte(0x02, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00055  *         HC595.ShiftByte(0x01, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00056  *         HC595.ShiftByte(0x00, ShiftReg::MSBFirst); HC595.Latch(); wait(0.2);
00057  *     }
00058  * }
00059  * @endcode
00060  */
00061 
00062 class ShiftReg
00063 {
00064 public:
00065     /** Bit order out format */
00066     enum BitOrd {
00067         MSBFirst = 0x80,  /**< Most  significant bit first */
00068         LSBFirst = 0x01   /**< Least significant bit first */
00069     };
00070 
00071     /** Create a ShiftReg interface to shift register
00072      *
00073      * @param data     Pin to serial input to shift register
00074      * @param store    Pin to store register
00075      * @param clock    Pin to shift into register
00076      */
00077     ShiftReg
00078     (PinName data
00079     ,PinName store
00080     ,PinName clock
00081     );
00082 
00083     /** Shift out 8-bit data via the serial pin
00084      *
00085      * @param data    Data to be shifted out via the serial pin
00086      * @param order   Bit order to shift out data. Default is MSBFirst
00087      */
00088     void 
00089     ShiftByte
00090     (int8_t  data
00091     ,BitOrd  ord    = MSBFirst
00092     );
00093     
00094     /** Shift out 1-bit data via the serial pin
00095      *
00096      * @param data    Data to be shifted out via the serial pin
00097      */
00098     void
00099     ShiftBit
00100     (int8_t  data = 0
00101     );
00102 
00103     /** Latch data out 
00104      */
00105     void 
00106     Latch();
00107 
00108 private:
00109     DigitalOut _ds;          // Serial in
00110     DigitalOut _st;          // store register or latch
00111     DigitalOut _sh;          // shift register
00112     BitOrd     _ord;         // Bit order to shift out data
00113 };
00114 
00115 #endif // _SHIFTREG_H