97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
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/*
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* gertboard.c:
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* Simple test for the SPI bus on the Gertboard
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*
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* Hardware setup:
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* D/A port 0 jumpered to A/D port 0.
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*
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* We output a sine wave on D/A port 0 and sample A/D port 0. We then
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* plot the input value on the terminal as a sort of vertical scrolling
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* oscilloscipe.
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*
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* Copyright (c) 2012-2013 Gordon Henderson. <projects@drogon.net>
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***********************************************************************
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* This file is part of wiringPi:
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* https://projects.drogon.net/raspberry-pi/wiringpi/
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*
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* wiringPi is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* wiringPi is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with wiringPi. If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************
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*/
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#include <stdio.h>
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#include <sys/ioctl.h>
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#include <stdlib.h>
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#include <math.h>
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// Gertboard D to A is an 8-bit unit.
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#define B_SIZE 256
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#include <wiringPi.h>
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#include <gertboard.h>
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int main (void)
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{
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double angle ;
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int i, inputValue ;
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int buffer [B_SIZE] ;
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int cols ;
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struct winsize w ;
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printf ("Raspberry Pi Gertboard SPI test program\n") ;
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printf ("=======================================\n") ;
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ioctl (fileno (stdin), TIOCGWINSZ, &w);
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cols = w.ws_col - 2 ;
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// Always initialise wiringPi. Use wiringPiSys() if you don't need
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// (or want) to run as root
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wiringPiSetupSys () ;
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// Initialise the Gertboard analog hardware at pin 100
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gertboardAnalogSetup (100) ;
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// Generate a Sine Wave and store in our buffer
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for (i = 0 ; i < B_SIZE ; ++i)
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{
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angle = ((double)i / (double)B_SIZE) * M_PI * 2.0 ;
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buffer [i] = (int)rint ((sin (angle)) * 127.0 + 128.0) ;
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}
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// Loop, output the sine wave on analog out port 0, read it into A-D port 0
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// and display it on the screen
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for (;;)
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{
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for (i = 0 ; i < B_SIZE ; ++i)
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{
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analogWrite (100, buffer [i]) ;
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inputValue = analogRead (100) ;
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// We don't need to wory about the scale or sign - the analog hardware is
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// a 10-bit value, so 0-1023. Just scale this to our terminal
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printf ("%*s\n", (inputValue * cols) / 1023, "*") ;
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delay (2) ;
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}
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}
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return 0 ;
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}
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