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