> I2S generated correct signal, bit clock, frame rate,
How did you verify that?
I used logic analyzer to check the I2S signal from STM32's I2S pins, bit clock, frame, data all decoded from the array data.
>data valid meaning my I2S signals matching with my prepared data array.
For the manual way to generate the data for sine wave, you are correct there are so many way, and I used the references online showing how to generate the buffer of data using sine wave in math.h header file.
The details is here
https://www.phippselectronics.com/i2s-audio-tutorial-variable-frequency-sine-wave-output/?srsltid=AfmBOooTV4wQHR4cb-eJ_hegJ-KJ6lrh3qPybHbS98dyWNejJAjF8iUq
In short
#include "limits.h"
#include "math.h"
const int Fs = 48000; // sample rate (Hz)
const int LUT_SIZE = 1024; // lookup table size
int16_t LUT[LUT_SIZE]; // our sine wave LUT
for (int i = 0; i < LUT_SIZE; ++i)
{
LUT[i] = (int16_t)roundf(SHRT_MAX * sinf(2.0f * M_PI * (float)i / LUT_SIZE));
} // fill LUT with 16 bit sine wave sample values
// frequency we want to generate (Hz)
int f = 1000;
// Generate sine wave with chosen frequency
const int BUFF_SIZE = 4096; // size of output buffer (samples)
int16_t buff[BUFF_SIZE]; // output buffer
// frequency we want to generate (Hz)
const float delta_phi = (float) f / Fs * LUT_SIZE;
// phase increment
float phase = 0.0f; // phase accumulator
// generate buffer of output
for (int i = 0; i < BUFF_SIZE; ++i)
{
int phase_i = (int)phase; // get integer part of our phase
buff[i] = LUT[phase_i]; // get sample value from LUT
phase += delta_phi; // increment phase
if (phase >= (float)LUT_SIZE) // handle wrap around
phase -= (float)LUT_SIZE;
}
Once you have the buffer data (or array of data) just send it to start it with HAL_I2S_Transmit_DMA function call
@waclawek.jan, may I ask which method you used to create your sine wave and how did you configured your I2S and how would you verify your signal so maybe I can follow and try to follow your steps to create a sine wave with the correct frequency?
