Dave Van Wagner / SWSPI

Software SPI allows non-standard SPI pins to be used for interfacing with SPI devices

Dependents:   ADNS5090 PB_Emma_Ethernet spi_test Final_Project ... more

SWSPI.cpp@0:6a500a08c7fd, 2014-02-04 (annotated)

Committer:
davervw
Date:
Tue Feb 04 06:54:01 2014 +0000
Revision:
0:6a500a08c7fd
First revision, tested with lpc1768, lpc11u24, lpc1114fn28, and lpc812

Who changed what in which revision?

UserRevisionLine numberNew contents of line
davervw 0:6a500a08c7fd 1 /* SWSPI, Software SPI library
davervw 0:6a500a08c7fd 2 * Copyright (c) 2012-2014, David R. Van Wagner, http://techwithdave.blogspot.com
davervw 0:6a500a08c7fd 3 *
davervw 0:6a500a08c7fd 4 * Permission is hereby granted, free of charge, to any person obtaining a copy
davervw 0:6a500a08c7fd 5 * of this software and associated documentation files (the "Software"), to deal
davervw 0:6a500a08c7fd 6 * in the Software without restriction, including without limitation the rights
davervw 0:6a500a08c7fd 7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
davervw 0:6a500a08c7fd 8 * copies of the Software, and to permit persons to whom the Software is
davervw 0:6a500a08c7fd 9 * furnished to do so, subject to the following conditions:
davervw 0:6a500a08c7fd 10 *
davervw 0:6a500a08c7fd 11 * The above copyright notice and this permission notice shall be included in
davervw 0:6a500a08c7fd 12 * all copies or substantial portions of the Software.
davervw 0:6a500a08c7fd 13 *
davervw 0:6a500a08c7fd 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
davervw 0:6a500a08c7fd 15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
davervw 0:6a500a08c7fd 16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
davervw 0:6a500a08c7fd 17 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
davervw 0:6a500a08c7fd 18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
davervw 0:6a500a08c7fd 19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
davervw 0:6a500a08c7fd 20 * THE SOFTWARE.
davervw 0:6a500a08c7fd 21 */
davervw 0:6a500a08c7fd 22
davervw 0:6a500a08c7fd 23 #include <mbed.h>
davervw 0:6a500a08c7fd 24 #include "SWSPI.h"
davervw 0:6a500a08c7fd 25
davervw 0:6a500a08c7fd 26 SWSPI::SWSPI(PinName mosi_pin, PinName miso_pin, PinName sclk_pin)
davervw 0:6a500a08c7fd 27 {
davervw 0:6a500a08c7fd 28 mosi = new DigitalOut(mosi_pin);
davervw 0:6a500a08c7fd 29 miso = new DigitalIn(miso_pin);
davervw 0:6a500a08c7fd 30 sclk = new DigitalOut(sclk_pin);
davervw 0:6a500a08c7fd 31 format(8);
davervw 0:6a500a08c7fd 32 frequency();
davervw 0:6a500a08c7fd 33 }
davervw 0:6a500a08c7fd 34
davervw 0:6a500a08c7fd 35 SWSPI::~SWSPI()
davervw 0:6a500a08c7fd 36 {
davervw 0:6a500a08c7fd 37 delete mosi;
davervw 0:6a500a08c7fd 38 delete miso;
davervw 0:6a500a08c7fd 39 delete sclk;
davervw 0:6a500a08c7fd 40 }
davervw 0:6a500a08c7fd 41
davervw 0:6a500a08c7fd 42 void SWSPI::format(int bits, int mode)
davervw 0:6a500a08c7fd 43 {
davervw 0:6a500a08c7fd 44 this->bits = bits;
davervw 0:6a500a08c7fd 45 this->mode = mode;
davervw 0:6a500a08c7fd 46 polarity = (mode >> 1) & 1;
davervw 0:6a500a08c7fd 47 phase = mode & 1;
davervw 0:6a500a08c7fd 48 sclk->write(polarity);
davervw 0:6a500a08c7fd 49 }
davervw 0:6a500a08c7fd 50
davervw 0:6a500a08c7fd 51 void SWSPI::frequency(int hz)
davervw 0:6a500a08c7fd 52 {
davervw 0:6a500a08c7fd 53 this->freq = hz;
davervw 0:6a500a08c7fd 54 }
davervw 0:6a500a08c7fd 55
davervw 0:6a500a08c7fd 56 int SWSPI::write(int value)
davervw 0:6a500a08c7fd 57 {
davervw 0:6a500a08c7fd 58 int read = 0;
davervw 0:6a500a08c7fd 59 for (int bit = bits-1; bit >= 0; --bit)
davervw 0:6a500a08c7fd 60 {
davervw 0:6a500a08c7fd 61 mosi->write(((value >> bit) & 0x01) != 0);
davervw 0:6a500a08c7fd 62
davervw 0:6a500a08c7fd 63 if (phase == 0)
davervw 0:6a500a08c7fd 64 {
davervw 0:6a500a08c7fd 65 if (miso->read())
davervw 0:6a500a08c7fd 66 read |= (1 << bit);
davervw 0:6a500a08c7fd 67 }
davervw 0:6a500a08c7fd 68
davervw 0:6a500a08c7fd 69 sclk->write(!polarity);
davervw 0:6a500a08c7fd 70
davervw 0:6a500a08c7fd 71 wait(1.0/freq/2);
davervw 0:6a500a08c7fd 72
davervw 0:6a500a08c7fd 73 if (phase == 1)
davervw 0:6a500a08c7fd 74 {
davervw 0:6a500a08c7fd 75 if (miso->read())
davervw 0:6a500a08c7fd 76 read |= (1 << bit);
davervw 0:6a500a08c7fd 77 }
davervw 0:6a500a08c7fd 78
davervw 0:6a500a08c7fd 79 sclk->write(polarity);
davervw 0:6a500a08c7fd 80
davervw 0:6a500a08c7fd 81 wait(1.0/freq/2);
davervw 0:6a500a08c7fd 82 }
davervw 0:6a500a08c7fd 83
davervw 0:6a500a08c7fd 84 return read;
davervw 0:6a500a08c7fd 85 }
davervw 0:6a500a08c7fd 86