wiringPi_Blueberry/examples/Gertboard/vumeter.c
2023-08-11 15:53:17 +08:00

153 lines
3.2 KiB
C

/*
* 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 ;
}