Half Duplex Version of SWSPI
Fork of SWSPI by
Revision 0:6a500a08c7fd, committed 2014-02-04
- Comitter:
- davervw
- Date:
- Tue Feb 04 06:54:01 2014 +0000
- Child:
- 1:17d758fe52f8
- Commit message:
- First revision, tested with lpc1768, lpc11u24, lpc1114fn28, and lpc812
Changed in this revision
SWSPI.cpp | Show annotated file Show diff for this revision Revisions of this file |
SWSPI.h | Show annotated file Show diff for this revision Revisions of this file |
--- /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; +} +
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/SWSPI.h Tue Feb 04 06:54:01 2014 +0000 @@ -0,0 +1,95 @@ +/* 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. + */ + +#ifndef SWSPI_H +#define SWSPI_H + +/** A software implemented SPI that can use any digital pins + * + * Useful when don't want to share a single SPI hardware among attached devices + * or when pinout doesn't match exactly to the target's SPI pins + * + * @code + * #include "mbed.h" + * #include "SWSPI.h" + * + * SWSPI spi(p5, p6, p7); // mosi, miso, sclk + * + * int main() + * { + * DigitalOut cs(p8); + * spi.format(8, 0); + * spi.frequency(10000000); + * cs.write(0); + * spi.write(0x9f); + * int jedecid = (spi.write(0) << 16) | (spi.write(0) << 8) | spi.write(0); + * cs.write(1); + * } + * @endcode + */ +class SWSPI +{ +private: + DigitalOut* mosi; + DigitalIn* miso; + DigitalOut* sclk; + int port; + int bits; + int mode; + int polarity; // idle clock value + int phase; // 0=sample on leading (first) clock edge, 1=trailing (second) + int freq; + +public: + /** Create SWSPI object + * + * @param mosi_pin + * @param miso_pin + * @param sclk_pin + */ + SWSPI(PinName mosi_pin, PinName miso_pin, PinName sclk_pin); + + /** Destructor */ + ~SWSPI(); + + /** Specify SPI format + * + * @param bits 8 or 16 are typical values + * @param mode 0, 1, 2, or 3 phase (bit1) and idle clock (bit0) + */ + void format(int bits, int mode = 0); + + /** Specify SPI clock frequency + * + * @param hz frequency (optional, defaults to 10000000) + */ + void frequency(int hz = 10000000); + + /** Write data and read result + * + * @param value data to write (see format for bit size) + * returns value read from device + */ + int write(int value); +}; + +#endif // SWSPI_H