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96 lines
2.6 KiB
96 lines
2.6 KiB
/* |
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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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