ex ELLA / SWSPI

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

Fork of SWSPI by Dave Van Wagner

SWSPI.cpp@1:9e0c0217646d, 2015-05-08 (annotated)

Committer:
lionello
Date:
Fri May 08 08:05:29 2015 +0000
Revision:
1:9e0c0217646d
Parent:
0:6a500a08c7fd
Child:
2:eafe3ec5fbf8
Made miso pin optional (accept NC)

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
lionello 1:9e0c0217646d 26 SWSPI::SWSPI(PinName mosi_pin, PinName miso_pin, PinName sclk_pin) : miso(NULL)
davervw 0:6a500a08c7fd 27 {
davervw 0:6a500a08c7fd 28 mosi = new DigitalOut(mosi_pin);
lionello 1:9e0c0217646d 29 if (miso_pin!= NC)
lionello 1:9e0c0217646d 30 miso = new DigitalIn(miso_pin);
davervw 0:6a500a08c7fd 31 sclk = new DigitalOut(sclk_pin);
davervw 0:6a500a08c7fd 32 format(8);
davervw 0:6a500a08c7fd 33 frequency();
davervw 0:6a500a08c7fd 34 }
davervw 0:6a500a08c7fd 35
davervw 0:6a500a08c7fd 36 SWSPI::~SWSPI()
davervw 0:6a500a08c7fd 37 {
davervw 0:6a500a08c7fd 38 delete mosi;
davervw 0:6a500a08c7fd 39 delete miso;
davervw 0:6a500a08c7fd 40 delete sclk;
davervw 0:6a500a08c7fd 41 }
davervw 0:6a500a08c7fd 42
davervw 0:6a500a08c7fd 43 void SWSPI::format(int bits, int mode)
davervw 0:6a500a08c7fd 44 {
davervw 0:6a500a08c7fd 45 this->bits = bits;
davervw 0:6a500a08c7fd 46 this->mode = mode;
davervw 0:6a500a08c7fd 47 polarity = (mode >> 1) & 1;
davervw 0:6a500a08c7fd 48 phase = mode & 1;
davervw 0:6a500a08c7fd 49 sclk->write(polarity);
davervw 0:6a500a08c7fd 50 }
davervw 0:6a500a08c7fd 51
davervw 0:6a500a08c7fd 52 void SWSPI::frequency(int hz)
davervw 0:6a500a08c7fd 53 {
davervw 0:6a500a08c7fd 54 this->freq = hz;
davervw 0:6a500a08c7fd 55 }
davervw 0:6a500a08c7fd 56
davervw 0:6a500a08c7fd 57 int SWSPI::write(int value)
davervw 0:6a500a08c7fd 58 {
davervw 0:6a500a08c7fd 59 int read = 0;
davervw 0:6a500a08c7fd 60 for (int bit = bits-1; bit >= 0; --bit)
davervw 0:6a500a08c7fd 61 {
davervw 0:6a500a08c7fd 62 mosi->write(((value >> bit) & 0x01) != 0);
davervw 0:6a500a08c7fd 63
davervw 0:6a500a08c7fd 64 if (phase == 0)
davervw 0:6a500a08c7fd 65 {
lionello 1:9e0c0217646d 66 if (miso && miso->read())
davervw 0:6a500a08c7fd 67 read |= (1 << bit);
davervw 0:6a500a08c7fd 68 }
davervw 0:6a500a08c7fd 69
davervw 0:6a500a08c7fd 70 sclk->write(!polarity);
davervw 0:6a500a08c7fd 71
davervw 0:6a500a08c7fd 72 wait(1.0/freq/2);
davervw 0:6a500a08c7fd 73
davervw 0:6a500a08c7fd 74 if (phase == 1)
davervw 0:6a500a08c7fd 75 {
lionello 1:9e0c0217646d 76 if (miso && miso->read())
davervw 0:6a500a08c7fd 77 read |= (1 << bit);
davervw 0:6a500a08c7fd 78 }
davervw 0:6a500a08c7fd 79
davervw 0:6a500a08c7fd 80 sclk->write(polarity);
davervw 0:6a500a08c7fd 81
davervw 0:6a500a08c7fd 82 wait(1.0/freq/2);
davervw 0:6a500a08c7fd 83 }
davervw 0:6a500a08c7fd 84
davervw 0:6a500a08c7fd 85 return read;
davervw 0:6a500a08c7fd 86 }
davervw 0:6a500a08c7fd 87