7 years, 5 months ago.

BTN problem

Hi , i have this program :

1. include "mbed.h"

DAC 20khz

1. define DAC_Frequency 20000

AnalogOut dac(A2);

DigitalIn btn(USER_BUTTON); DigitalOut led(D15);

Timer tim; Ticker tic;

C D E F G A B C int freq_table[] = {262, 293, 330, 349, 392, 440, 493, 523}; int sel;

void DAC_Int(void) { int period = 1000000 / freq_table[sel]; int pos = tim.read_us() % period;

Square wave dac = pos > (period / 2) ? 1 : 0;

Sine wave dac = sin(pos * 3.14f * 2 / period) / 2.0f + 0.5f; }

int main() { sel = 0;

tim.start();

tic.attach_us(&DAC_Int, 1000000 / DAC_Frequency);

while(1) { if (btn == 1) { led=!led; sel++; if (sel > 7) sel = 0; wait(0.5); } } }

With BTN press we change the frequency of sine wave . But that doesn't work on my bord ( Nucleo F091). Someone have any idea ?

Thanks