Hello pieter
I change code to this and use 3.3 V of ardino pin
#define LIN_OUT 1 // use the log output function
#define FHT_N 256 // set to 256 point fht
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#include <FHT.h> // include the library
const double a12200 = pow(12200,2);
const double a206 = pow(20.6,2);
const double a1077 = pow(107.7,2);
const double a7379 = pow(737.9,2);
const double CORR = 0;
const int GAIN = 1;
int f;
double RA,CF,f2,f4,C,ADCNUM;
void setup() {
Serial.begin(115200); // use the serial port
ADCSRB = 0; // Free running mode
ADMUX = (DEFAULT << 6) | 0; // A0
sbi(ADCSRA, ADEN); // Enable ADC
sbi(ADCSRA, ADATE); // Auto trigger
sbi(ADCSRA, ADSC); // Start conversion
// 19.231 kHz
sbi(ADCSRA, ADPS2);
sbi(ADCSRA, ADPS1);
cbi(ADCSRA, ADPS0);
}
void loop() {
do {
cli(); // UDRE interrupt slows this way down on arduino1.0
for (int i = 0 ; i < FHT_N ; i++) { // save 256 samples
while (!(ADCSRA & _BV(ADIF))); // wait for adc to be ready
sbi(ADCSRA, ADIF); // Clear interrupt flag
byte m = ADCL; // fetch adc data
byte j = ADCH;
int k = (j << 8) | m; // form into an int
k -= 0x0200; // form into a signed int
k <<= 6; // form into a 16b signed int
fht_input[i] = k; // put re3l data into bins
}
fht_window(); // window the data for better frequency response
fht_reorder(); // reorder the data before doing the fht
fht_run(); // process the data in the fht
fht_mag_lin(); // take the output of the fht
sei();
for (uint8_t i = 0 ; i < FHT_N / 2 ; i++) {
f=i * 19231UL / FHT_N;
Serial.print(f);
Serial.print(" HZ:");
Serial.println(fht_lin_out[i]); // send out the data
}
} while(0);
while(1);
}
Result is for frequency 1051 Hz is 2928
0 HZ:16000
75 HZ:7936
150 HZ:23
225 HZ:36
300 HZ:6
375 HZ:11
450 HZ:9
525 HZ:30
600 HZ:20
676 HZ:30
751 HZ:4
826 HZ:19
901 HZ:59
976 HZ:1664
1051 HZ:2928
1126 HZ:1296
1201 HZ:29
1277 HZ:20
1352 HZ:17
1427 HZ:31
1502 HZ:10
1577 HZ:21
1652 HZ:20
1727 HZ:24
1802 HZ:11
1878 HZ:14
1953 HZ:46
2028 HZ:780
2103 HZ:1224
2178 HZ:468
2253 HZ:23
2328 HZ:17
2403 HZ:7
2478 HZ:5
2554 HZ:12
2629 HZ:13
2704 HZ:19
2779 HZ:17
2854 HZ:12
2929 HZ:15
3004 HZ:13
3079 HZ:81
3155 HZ:130
3230 HZ:54
3305 HZ:12
3380 HZ:26
3455 HZ:20
3530 HZ:38
3605 HZ:17
3680 HZ:36
3756 HZ:32
3831 HZ:20
3906 HZ:13
3981 HZ:4
4056 HZ:55
4131 HZ:370
4206 HZ:468
4281 HZ:135
4357 HZ:26
4432 HZ:16
4507 HZ:16
4582 HZ:7
4657 HZ:26
4732 HZ:27
4807 HZ:13
4882 HZ:3
4957 HZ:12
5033 HZ:8
5108 HZ:28
5183 HZ:178
5258 HZ:197
5333 HZ:46
5408 HZ:8
5483 HZ:9
5558 HZ:26
5634 HZ:46
5709 HZ:17
5784 HZ:9
5859 HZ:26
5934 HZ:6
6009 HZ:9
6084 HZ:1
6159 HZ:20
6235 HZ:72
6310 HZ:74
6385 HZ:10
6460 HZ:13
6535 HZ:11
6610 HZ:36
6685 HZ:25
6760 HZ:35
6836 HZ:20
6911 HZ:29
6986 HZ:6
7061 HZ:17
7136 HZ:13
7211 HZ:19
7286 HZ:59
7361 HZ:52
7436 HZ:2
7512 HZ:17
7587 HZ:7
7662 HZ:12
7737 HZ:44
7812 HZ:42
7887 HZ:6
7962 HZ:6
8037 HZ:5
8113 HZ:8
8188 HZ:8
8263 HZ:20
8338 HZ:44
8413 HZ:29
8488 HZ:1
8563 HZ:3
8638 HZ:9
8714 HZ:44
8789 HZ:51
8864 HZ:18
8939 HZ:10
9014 HZ:14
9089 HZ:12
9164 HZ:8
9239 HZ:10
9315 HZ:31
9390 HZ:36
9465 HZ:17
9540 HZ:9
I dont know how this number change to voltage
Please help me and say what is furmula for do it and write it for me