initial cleanup and mapping

examples/Gertboard/vumeter.c

@@ -0,0 +1,152 @@
+/*
+ * vumeter.c:
+ *	Simple VU meter
+ *
+ * Heres the theory:
+ *	We will sample at 4000 samples/sec and put the data into a
+ *	low-pass filter with a depth of 1000 samples. This will give
+ *	us 1/4 a second of lag on the signal, but I think it might
+ *	produce a more pleasing output.
+ *
+ *	The input of the microphone should be at mid-pont with no
+ *	sound input, but we might have to sample that too, to get
+ *	our reference zero...
+ *
+ *	Copyright (c) 2013 Gordon Henderson
+ ***********************************************************************
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+
+#include <wiringPi.h>
+#include <gertboard.h>
+
+#ifndef	TRUE
+#define	TRUE	(1==1)
+#define	FALSE	(!TRUE)
+#endif
+
+#define	B_SIZE	1000
+#define	S_SIZE	 128
+
+static int buffer [B_SIZE] ;
+static int bPtr = 0 ;
+
+/*
+ * ledPercent:
+ *	Output the given value as a percentage on the LEDs
+ *********************************************************************************
+ */
+
+static void ledPercent (int percent)
+{
+  unsigned int output = 0 ;
+
+  if (percent > 11) output |= 0x01 ;
+  if (percent > 22) output |= 0x02 ;
+  if (percent > 33) output |= 0x04 ;
+  if (percent > 44) output |= 0x08 ;
+  if (percent > 55) output |= 0x10 ;
+  if (percent > 66) output |= 0x20 ;
+  if (percent > 77) output |= 0x40 ;
+  if (percent > 88) output |= 0x80 ;
+
+  digitalWriteByte (output) ;
+}
+
+static unsigned int tPeriod, tNextSampleTime ;
+
+/*
+ * sample:
+ *	Get a sample from the Gertboard. If not enough time has elapsed
+ *	since the last sample, then wait...
+ *********************************************************************************
+ */
+
+static void sample (void)
+{
+  unsigned int tFuture ;
+
+// Calculate the future sample time
+
+  tFuture = tPeriod + tNextSampleTime ;
+
+// Wait until the next sample time
+
+  while (micros () < tNextSampleTime)
+    ;
+  
+  buffer [bPtr] = gertboardAnalogRead (0) ;
+
+  tNextSampleTime = tFuture ;
+}
+
+
+int main ()
+{
+  int quietLevel, min, max ;
+  int i, sum ;
+  unsigned int tStart, tEnd ;
+
+  printf ("\n") ;
+  printf ("Gertboard demo: VU Meter\n") ;
+  printf ("========================\n") ;
+
+  wiringPiSetup     () ;
+  gertboardSPISetup () ;
+
+  ledPercent (0) ;
+  for (i = 0 ; i < 8 ; ++i)
+    pinMode (i, OUTPUT) ;
+
+  for (bPtr = 0 ; bPtr < B_SIZE ; ++bPtr)
+    buffer [bPtr] = 99 ;
+
+  tPeriod = 1000000 / 1000 ;
+
+  printf ("Shhhh.... ") ; fflush (stdout) ;
+  delay (1000) ;
+  printf ("Sampling quiet... ") ; fflush (stdout) ;
+
+  tStart = micros () ;
+
+  tNextSampleTime = micros () ;
+  for (bPtr = 0 ; bPtr < B_SIZE ; ++bPtr)
+    sample () ;
+
+  tEnd = micros () ;
+
+  quietLevel = 0 ;
+  max =    0 ;
+  min = 1024 ;
+  for (i = 0 ; i < B_SIZE ; ++i)
+  {
+    quietLevel += buffer [i] ;
+    if (buffer [i] > max) max = buffer [i] ;
+    if (buffer [i] < min) min = buffer [i] ;
+  }
+  quietLevel /= B_SIZE ;
+
+  printf ("Done. Quiet level is: %d [%d:%d] [%d:%d]\n", quietLevel, min, max, quietLevel - min, max - quietLevel) ;
+
+  printf ("Time taken for %d reads: %duS\n", B_SIZE, tEnd - tStart) ;
+
+  for (bPtr = 0 ;;)
+  {
+    sample () ;
+    sum = 0 ;
+    for (i = 0 ; i < S_SIZE ; ++i)
+      sum += buffer [i] ;
+    sum /= S_SIZE ;
+    sum = abs (quietLevel - sum) ;
+    sum = (sum * 1000) / quietLevel ;
+    ledPercent (sum) ;
+    if (++bPtr > S_SIZE)
+      bPtr = 0 ;
+  }
+
+
+  return 0 ;
+}