Hi All,
I am using a P-NUCLEO-WB55 development board in BVLINKWB1_V2.0.0 project.
Project ST Link Here: https://www.st.com/en/embedded-software/fp-aud-bvlinkwb1.html
In this project, I would like to change the SAI1_SD_PIN from PA10 to PB15 in P-NUCLEO-WB55 board. But I faced a weird situation which is excessive noise. I will appreciate if you can help me to solve the problem. During this journey, I will mention about my progress step by step to be clear. I'm just a beginner with PDM microphones. As much as I learned, I had some trials in line with my needs. In this process, I'm sorry if I have made some mistakes that annoy you or that should not be done.
In this project, if I directly build and upload the .elf file the firmware is working very well. You can listen the recorded voice (voice name "PA10_Test_Record.wav") that was recorded by "ST BLE Sensor Classic" IOS app through P-NUCLEO-WB55.
As you can see the screenshot below: (The voice can be seen clearly)
Until here everything is OK.
From below
// cca02m2_audio.h file
#define AUDIO_IN_SAI_SCK_PIN GPIO_PIN_8
#define AUDIO_IN_SAI_SCK_GPIO_PORT GPIOA
#define AUDIO_IN_SAI_SCK_GPIO_CLK_ENABLE() __GPIOA_CLK_ENABLE()
#define AUDIO_IN_SAI_SCK_AF GPIO_AF3_SAI1
#define AUDIO_IN_SAI_SD_PIN GPIO_PIN_10
#define AUDIO_IN_SAI_SD_GPIO_PORT GPIOA
#define AUDIO_IN_SAI_SD_GPIO_CLK_ENABLE() __GPIOA_CLK_ENABLE();
#define AUDIO_IN_SAI_SD_AF GPIO_AF3_SAI1
// In CCA02M2_AUDIO_IN_Init function
hAudioInSai.Init.PdmInit.Activation = ENABLE;
hAudioInSai.Init.PdmInit.ClockEnable = SAI_PDM_CLOCK2_ENABLE;
hAudioInSai.FrameInit.FrameLength = 16;
if ( AudioInCtx[Instance].ChannelsNbr <= 2U)
{
hAudioInSai.Init.PdmInit.MicPairsNbr = 1;
hAudioInSai.Init.AudioFrequency = ((PDM_Clock_Freq * 1000U) / hAudioInSai.FrameInit.FrameLength ) * 1U;
}
else
{
hAudioInSai.Init.PdmInit.MicPairsNbr = 2;
hAudioInSai.Init.AudioFrequency = ((PDM_Clock_Freq * 1000U) / hAudioInSai.FrameInit.FrameLength ) * 2U;
}
To below:
// cca02m2_audio.h file
#define AUDIO_IN_SAI_SCK_PIN GPIO_PIN_8
#define AUDIO_IN_SAI_SCK_GPIO_PORT GPIOA
#define AUDIO_IN_SAI_SCK_GPIO_CLK_ENABLE() __GPIOA_CLK_ENABLE()
#define AUDIO_IN_SAI_SCK_AF GPIO_AF13_SAI1
#define AUDIO_IN_SAI_SD_PIN GPIO_PIN_15
#define AUDIO_IN_SAI_SD_GPIO_PORT GPIOB
#define AUDIO_IN_SAI_SD_GPIO_CLK_ENABLE() __GPIOB_CLK_ENABLE();
#define AUDIO_IN_SAI_SD_AF GPIO_AF13_SAI1
Also, I edited some lines into "CCA02M2_AUDIO_IN_Init" function like below:
// In CCA02M2_AUDIO_IN_Init function
hAudioInSai.Init.PdmInit.Activation = DISABLE;
//hAudioInSai.Init.PdmInit.ClockEnable = SAI_PDM_CLOCK2_ENABLE;
hAudioInSai.FrameInit.FrameLength = 16;
if ( AudioInCtx[Instance].ChannelsNbr <= 2U)
{
hAudioInSai.Init.PdmInit.MicPairsNbr = 1;
hAudioInSai.Init.AudioFrequency = ((PDM_Clock_Freq * 1000U) / hAudioInSai.FrameInit.FrameLength ) * 1U;
}
else
{
hAudioInSai.Init.PdmInit.MicPairsNbr = 2;
hAudioInSai.Init.AudioFrequency = ((PDM_Clock_Freq * 1000U) / hAudioInSai.FrameInit.FrameLength ) * 2U;
}
After, these changes, I recorded the voice and it was too noisy like recording a voice during driving an open car. Sensitivity was decreased. I have to be close to the microphone around 2-3 cm to record my voice. (Normally 30 cm was pretty enough to hear the voice) You can see the output result below: (Same sound, closer distance) In addition, you can find the voice record in the attachment as "PB15_Noisy_Test_Record.wav"
I must change PA10 pin to PB15 pin. Because the only available pin was PB15 on my design. If you ask me why you changed AF number you can see the table from STM32WB55 datasheet:
Default project AF Pins:
After change AF Pins:
As a result, I should be able to run the project in the same way by using the PB15 pin instead of the PA10 pin on the default project pins PA8 clock and PA10 data pins.
Thank you for your time.
