Updated from git.drogon.net
diff --git a/examples/Gertboard/voltmeter.c b/examples/Gertboard/voltmeter.c
new file mode 100644
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--- /dev/null
+++ b/examples/Gertboard/voltmeter.c
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+/*
+ * voltmeter.c:
+ * Demonstrate use of the Gertboard A to D converter to make
+ * a simple voltmeter.
+ *
+ * Copyright (c) 2012-2013 Gordon Henderson. <projects@drogon.net>
+ ***********************************************************************
+ * 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 <http://www.gnu.org/licenses/>.
+ ***********************************************************************
+ */
+
+#include <stdio.h>
+
+#include <wiringPi.h>
+#include <gertboard.h>
+
+int main ()
+{
+ int x1, x2 ;
+ double v1, v2 ;
+
+ printf ("\n") ;
+ printf ("Gertboard demo: Simple Voltmeters\n") ;
+ printf ("=================================\n") ;
+
+// 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) ;
+
+ printf ("\n") ;
+ printf ("| Channel 0 | Channel 1 |\n") ;
+
+ for (;;)
+ {
+
+// Read the 2 channels:
+
+ x1 = analogRead (100) ;
+ x2 = analogRead (101) ;
+
+// Convert to a voltage:
+
+ v1 = (double)x1 / 1023.0 * 3.3 ;
+ v2 = (double)x2 / 1023.0 * 3.3 ;
+
+// Print
+
+ printf ("| %6.3f | %6.3f |\r", v1, v2) ;
+ fflush (stdout) ;
+ }
+
+ return 0 ;
+}
+