Software SPI allows non-standard SPI pins to be used for interfacing with SPI devices
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Diff: SWSPI.cpp
- Revision:
- 0:6a500a08c7fd
- Child:
- 1:9e0c0217646d
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/SWSPI.cpp Tue Feb 04 06:54:01 2014 +0000 @@ -0,0 +1,86 @@ +/* SWSPI, Software SPI library + * Copyright (c) 2012-2014, David R. Van Wagner, http://techwithdave.blogspot.com + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include <mbed.h> +#include "SWSPI.h" + +SWSPI::SWSPI(PinName mosi_pin, PinName miso_pin, PinName sclk_pin) +{ + mosi = new DigitalOut(mosi_pin); + miso = new DigitalIn(miso_pin); + sclk = new DigitalOut(sclk_pin); + format(8); + frequency(); +} + +SWSPI::~SWSPI() +{ + delete mosi; + delete miso; + delete sclk; +} + +void SWSPI::format(int bits, int mode) +{ + this->bits = bits; + this->mode = mode; + polarity = (mode >> 1) & 1; + phase = mode & 1; + sclk->write(polarity); +} + +void SWSPI::frequency(int hz) +{ + this->freq = hz; +} + +int SWSPI::write(int value) +{ + int read = 0; + for (int bit = bits-1; bit >= 0; --bit) + { + mosi->write(((value >> bit) & 0x01) != 0); + + if (phase == 0) + { + if (miso->read()) + read |= (1 << bit); + } + + sclk->write(!polarity); + + wait(1.0/freq/2); + + if (phase == 1) + { + if (miso->read()) + read |= (1 << bit); + } + + sclk->write(polarity); + + wait(1.0/freq/2); + } + + return read; +} +