Software SPI allows non-standard SPI pins to be used for interfacing with SPI devices
Fork of SWSPI by
SWSPI.cpp@2:eafe3ec5fbf8, 2015-05-08 (annotated)
- Committer:
- lionello
- Date:
- Fri May 08 08:23:58 2015 +0000
- Revision:
- 2:eafe3ec5fbf8
- Parent:
- 1:9e0c0217646d
- Child:
- 3:8c19911bdb58
CPU and memory optimizations
Who changed what in which revision?
User | Revision | Line number | New 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 | 2:eafe3ec5fbf8 | 26 | SWSPI::SWSPI(PinName mosi_pin, PinName miso_pin, PinName sclk_pin) |
lionello | 2:eafe3ec5fbf8 | 27 | : mosi(mosi_pin), |
lionello | 2:eafe3ec5fbf8 | 28 | miso(NULL), |
lionello | 2:eafe3ec5fbf8 | 29 | sclk(sclk_pin) |
davervw | 0:6a500a08c7fd | 30 | { |
lionello | 1:9e0c0217646d | 31 | if (miso_pin!= NC) |
lionello | 1:9e0c0217646d | 32 | miso = new DigitalIn(miso_pin); |
davervw | 0:6a500a08c7fd | 33 | format(8); |
davervw | 0:6a500a08c7fd | 34 | frequency(); |
davervw | 0:6a500a08c7fd | 35 | } |
davervw | 0:6a500a08c7fd | 36 | |
davervw | 0:6a500a08c7fd | 37 | SWSPI::~SWSPI() |
davervw | 0:6a500a08c7fd | 38 | { |
davervw | 0:6a500a08c7fd | 39 | delete miso; |
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 | polarity = (mode >> 1) & 1; |
davervw | 0:6a500a08c7fd | 46 | phase = mode & 1; |
lionello | 2:eafe3ec5fbf8 | 47 | sclk.write(polarity); |
davervw | 0:6a500a08c7fd | 48 | } |
davervw | 0:6a500a08c7fd | 49 | |
davervw | 0:6a500a08c7fd | 50 | void SWSPI::frequency(int hz) |
davervw | 0:6a500a08c7fd | 51 | { |
lionello | 2:eafe3ec5fbf8 | 52 | // TODO: need wait_ns taking int |
lionello | 2:eafe3ec5fbf8 | 53 | this->delay_s = 0.5f/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; |
lionello | 2:eafe3ec5fbf8 | 59 | for (unsigned bit = 1 << (bits-1); bit; bit >>= 1) |
davervw | 0:6a500a08c7fd | 60 | { |
lionello | 2:eafe3ec5fbf8 | 61 | mosi.write((value & bit) != 0); |
davervw | 0:6a500a08c7fd | 62 | |
davervw | 0:6a500a08c7fd | 63 | if (phase == 0) |
davervw | 0:6a500a08c7fd | 64 | { |
lionello | 1:9e0c0217646d | 65 | if (miso && miso->read()) |
davervw | 0:6a500a08c7fd | 66 | read |= (1 << bit); |
davervw | 0:6a500a08c7fd | 67 | } |
davervw | 0:6a500a08c7fd | 68 | |
lionello | 2:eafe3ec5fbf8 | 69 | sclk.write(!polarity); |
davervw | 0:6a500a08c7fd | 70 | |
lionello | 2:eafe3ec5fbf8 | 71 | wait(delay_s); |
davervw | 0:6a500a08c7fd | 72 | |
davervw | 0:6a500a08c7fd | 73 | if (phase == 1) |
davervw | 0:6a500a08c7fd | 74 | { |
lionello | 1:9e0c0217646d | 75 | if (miso && miso->read()) |
davervw | 0:6a500a08c7fd | 76 | read |= (1 << bit); |
davervw | 0:6a500a08c7fd | 77 | } |
davervw | 0:6a500a08c7fd | 78 | |
lionello | 2:eafe3ec5fbf8 | 79 | sclk.write(polarity); |
davervw | 0:6a500a08c7fd | 80 | |
lionello | 2:eafe3ec5fbf8 | 81 | wait(delay_s); |
davervw | 0:6a500a08c7fd | 82 | } |
davervw | 0:6a500a08c7fd | 83 | |
davervw | 0:6a500a08c7fd | 84 | return read; |
davervw | 0:6a500a08c7fd | 85 | } |