ShiftOut.h

00001 #ifndef SHIFTOUT_H
00002 #define SHIFTOUT_H
00003 
00004 #include <mbed.h>
00005 
00006 /** A simple serial driver for a shift register that uses only three digital out pins leaving SPI and i2c free. 
00007  * ShiftOut can be configured for any size shift register but defaults to eight bits.
00008  */
00009 class ShiftOut {
00010 
00011     public :
00012     
00013         /** Constructs a new ShiftOut with the given three pins.
00014          * @param clk - the pin to use for the shift register clock.
00015          * @param data - the pin to use for the shift register data line.
00016          * @param latch - the pin to use for the shift register latch.
00017          * @param registerCount - the number of registers in the shift register, defaults to eight.
00018          */
00019         ShiftOut(PinName clk, PinName data, PinName latch, int8_t registerCount = 0x08) {
00020             clkout = new DigitalOut(clk);
00021             dataout = new DigitalOut(data);
00022             latchout = new DigitalOut(latch);
00023             this->registerCount = registerCount;
00024         }
00025         
00026         ~ShiftOut() {
00027             delete clkout;
00028             delete dataout;
00029             delete latchout;
00030         }
00031         
00032         /** Writes the given integer to the shift register
00033          */
00034         void write(int data) {
00035             *latchout = 0;
00036             for (int i = registerCount - 1; i >=  0; i--) {
00037                 *clkout = 0;
00038                 *dataout = (data & (1 << i)) != 0;
00039                 *clkout = 1;
00040             }
00041             *latchout = 1;
00042         }
00043         
00044         void set_latch (int val){
00045             *latchout = val;
00046          }
00047          
00048     private :
00049         DigitalOut *clkout;
00050         DigitalOut *dataout;
00051         DigitalOut *latchout;
00052         int8_t registerCount;     
00053 };
00054 
00055 #endif