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BSP_AUDIO_OUT_Play() Buffer Size Parameter

Associate III

I am programming an SMT32F69I-DISCO board to output a SINE wave. I am having trouble with the Size parameter of the BSP_AUDIO_OUT_Play() function. I have a buffer of 100 that I am filling with my SINE values:

int16_t dataI2S[100];

Here are my calls of the functions to initialize and play audio @48 KHz:


BSP_AUDIO_OUT_Play(dataI2S, (uint32_t)200);

Here is what it looks like when I put 128 as the Size parameter:

0693W00000GYZcRQAX.bmpWhen I set it to 100:

0693W00000GYZdKQAX.bmpWhen I set to 200:


According to the function definition I put below, it sounds like it should be set to 200 because it's the size in bytes.


 * @brief Starts playing audio stream from a data buffer for a determined size.

 * @param pBuffer: Pointer to the buffer

 * @param Size: Number of audio data BYTES.

 * @retval AUDIO_OK if correct communication, else wrong communication


uint8_t BSP_AUDIO_OUT_Play(uint16_t* pBuffer, uint32_t Size)

Anyone have any ideas what I am doing wrong here? Many thanks!


The period is consistent for each data length. How do you know the data you're sending isn't what is displayed? How are you initializing the array?

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Associate III

Yes, it seems that I only have 64 values in my array, not 100! Can't believe I did not catch that. Thank you!

//Sine Wave variables

sample_dt = F_OUT/F_SAMPLE;

sample_N = F_SAMPLE/F_OUT;

uint16_t dataI2S[sample_N*2];

//Build Sine wave

for(uint16_t i=0; i<sample_N; i++)


mySinVal = sinf(i*2*PI*sample_dt);

dataI2S[i*2] = (mySinVal )*8000+4000;  //Right data

dataI2S[i*2 + 1] =(mySinVal )*8000+4000; //Left data