80 lines
2.2 KiB
C++
80 lines
2.2 KiB
C++
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/*
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Bit-banged SPI class
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Author: Nick Gammon
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Date: 24 March 2013
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PERMISSION TO DISTRIBUTE
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Permission is hereby granted, free of charge, to any person obtaining a copy of this software
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and associated documentation files (the "Software"), to deal in the Software without restriction,
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including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
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and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
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subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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LIMITATION OF LIABILITY
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The software is provided "as is", without warranty of any kind, express or implied,
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including but not limited to the warranties of merchantability, fitness for a particular
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purpose and noninfringement. In no event shall the authors or copyright holders be liable
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for any claim, damages or other liability, whether in an action of contract,
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tort or otherwise, arising from, out of or in connection with the software
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or the use or other dealings in the software.
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*/
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#include <bitBangedSPI.h>
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void bitBangedSPI::begin ()
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{
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if (mosi_ != NO_PIN)
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pinMode (mosi_, OUTPUT);
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if (miso_ != NO_PIN)
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pinMode (miso_, INPUT);
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pinMode (sck_, OUTPUT);
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} // end of bitBangedSPI::begin
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// Bit Banged SPI transfer
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byte bitBangedSPI::transfer (byte c)
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{
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// loop for each bit
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for (byte bit = 0; bit < 8; bit++)
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{
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// set up MOSI on falling edge of previous SCK (sampled on rising edge)
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if (mosi_ != NO_PIN)
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{
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if (c & 0x80)
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digitalWrite (mosi_, HIGH);
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else
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digitalWrite (mosi_, LOW);
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}
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// finished with MS bit, get read to receive next bit
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c <<= 1;
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// read MISO
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if (miso_ != NO_PIN)
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c |= digitalRead (miso_) != 0;
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// clock high
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digitalWrite (sck_, HIGH);
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// delay between rise and fall of clock
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delayMicroseconds (delayUs_);
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// clock low
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digitalWrite (sck_, LOW);
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// delay between rise and fall of clock
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delayMicroseconds (delayUs_);
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} // end of for loop, for each bit
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return c;
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} // end of bitBangedSPI::transfer
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