PDM working example

Question

hi,
Is there any working PDM example for nRF52832? or can anyone give a sample initialization code for PDM with easyDMA using the inbuilt nrf_pdm_drv functions? 
 Regardss,
Vishnu

Sigurd · Accepted Answer

Hi, We don't have any full examples yet. But here is some code to get you started: #include "nrf_drv_pdm.h" #define CONFIG_PDM_BUFFER_SIZE_SAMPLES 320 // PDM Decimation Filter Gain <0x00-0x50> // For details on the PDM decimation filter, see the 'Decimation filter' section in the nRF52 Product Specification document. #define CONFIG_PDM_GAIN 0x28 // PDM CLK Pin #define CONFIG_IO_PDM_CLK 0x06 // PDM DATA Pin #define CONFIG_IO_PDM_DATA 0x05 // PDM Microphone Power Control Pin #define CONFIG_IO_PDM_MIC_PWR_CTRL 0x1A /**@brief Audio buffer handler. */ typedef void (*drv_audio_buffer_handler_t)(int16_t *p_buffer, uint16_t samples); static int16_t m_pdm_buff[2][CONFIG_PDM_BUFFER_SIZE_SAMPLES]; static drv_audio_buffer_handler_t m_buffer_handler; static void m_audio_buffer_handler(int16_t *p_buffer, uint16_t samples) { // Audio processing } static void drv_audio_pdm_event_handler(uint32_t *p_buffer, uint16_t length) { m_buffer_handler((int16_t *)p_buffer, length); } uint32_t drv_audio_init(drv_audio_buffer_handler_t buffer_handler) { nrf_drv_pdm_config_t pdm_cfg = NRF_DRV_PDM_DEFAULT_CONFIG(CONFIG_IO_PDM_CLK, CONFIG_IO_PDM_DATA, m_pdm_buff[0], m_pdm_buff[1], CONFIG_PDM_BUFFER_SIZE_SAMPLES); if (buffer_handler == NULL) { return NRF_ERROR_INVALID_PARAM; } m_buffer_handler = buffer_handler; pdm_cfg.gain_l = CONFIG_PDM_GAIN; pdm_cfg.gain_r = CONFIG_PDM_GAIN; return nrf_drv_pdm_init(&pdm_cfg, drv_audio_pdm_event_handler); } /** * @brief Function for application main entry. */ int main(void) { uint32_t err_code; err_code = drv_audio_init(m_audio_buffer_handler); APP_ERROR_CHECK(err_code); err_code = nrf_drv_pdm_start(); APP_ERROR_CHECK(err_code); while (true) { // Do nothing. } } /** @} */ I also recommend taking a look at the PDM driver. It's located in SDK_folder\components\drivers_nrf\pdm

PDM working example

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