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Nathan Seidle
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Add example
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‎libraries/PDM/examples/Example1_MicrophoneOutput/Example1_MicrophoneOutput.ino

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/* Author: Nathan Seidle
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Created: July 24, 2019
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License: MIT. See SparkFun Arduino Apollo3 Project for more information
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This example demonstrates how to use the PDM microphone on Artemis boards.
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*/
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#define ARM_MATH_CM4
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#include <arm_math.h>
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//*****************************************************************************
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//
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// Example parameters.
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//
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//*****************************************************************************
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#define PDM_FFT_SIZE 4096
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//uint32_t pdmDataBufferSize = 4096;
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#define pdmDataBufferSize 4096
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//#define PDM_FFT_BYTES (PDM_FFT_SIZE * 2)
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#define PRINT_PDM_DATA 0
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#define PRINT_FFT_DATA 0
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//*****************************************************************************
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//
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// Global variables.
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//
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//*****************************************************************************
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//uint32_t g_ui32PDMDataBuffer[pdmDataBufferSize];
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uint32_t pdmDataBuffer[pdmDataBufferSize];
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float g_fPDMTimeDomain[pdmDataBufferSize * 2];
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float g_fPDMFrequencyDomain[pdmDataBufferSize * 2];
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float g_fPDMMagnitudes[pdmDataBufferSize * 2];
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uint32_t sampleFreq;
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#include <PDM.h> //Include PDM library included with the Aruino_Apollo3 core
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AP3_PDM myPDM;
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void setup()
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{
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Serial.begin(9600);
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Serial.println("SparkFun PDM Example");
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// Turn on the PDM, set it up for our chosen recording settings, and start
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// the first DMA transaction.
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if (myPDM.begin(22, 23) == false) //Data, clock - These are the pin names from variant file, not pad names
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{
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Serial.println("PDM Init failed. Are you sure these pins are PDM capable?");
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while (1);
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}
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Serial.println("PDM Initialized");
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//myPDM.setClockSpeed(AM_HAL_PDM_CLK_3MHZ);
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//myPDM.setClockDivider(AM_HAL_PDM_MCLKDIV_1);
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//myPDM.setGain(AM_HAL_PDM_GAIN_P210DB);
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//myPDM.setChannel(AM_HAL_PDM_CHANNEL_STEREO);
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pdm_config_print();
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am_hal_pdm_fifo_flush(myPDM._PDMhandle);
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myPDM.getData(pdmDataBuffer, pdmDataBufferSize);
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}
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void loop()
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{
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am_hal_interrupt_master_disable();
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if (myPDM.available())
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{
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pcm_fft_print();
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while (PRINT_PDM_DATA || PRINT_FFT_DATA);
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// Start converting the next set of PCM samples.
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myPDM.getData(pdmDataBuffer, pdmDataBufferSize);
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}
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// Go to Deep Sleep.
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am_hal_sysctrl_sleep(AM_HAL_SYSCTRL_SLEEP_DEEP);
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am_hal_interrupt_master_enable();
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}
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//*****************************************************************************
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//
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// Analyze and print frequency data.
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//
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//*****************************************************************************
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void
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pcm_fft_print(void)
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{
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float fMaxValue;
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uint32_t ui32MaxIndex;
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int16_t *pi16PDMData = (int16_t *) pdmDataBuffer;
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uint32_t ui32LoudestFrequency;
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//
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// Convert the PDM samples to floats, and arrange them in the format
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// required by the FFT function.
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//
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for (uint32_t i = 0; i < PDM_FFT_SIZE; i++)
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{
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if (PRINT_PDM_DATA)
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{
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Serial.printf("%d\n", pi16PDMData[i]);
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}
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g_fPDMTimeDomain[2 * i] = pi16PDMData[i] / 1.0;
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g_fPDMTimeDomain[2 * i + 1] = 0.0;
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}
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if (PRINT_PDM_DATA)
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{
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Serial.printf("END\n");
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}
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//
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// Perform the FFT.
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//
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arm_cfft_radix4_instance_f32 S;
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arm_cfft_radix4_init_f32(&S, PDM_FFT_SIZE, 0, 1);
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arm_cfft_radix4_f32(&S, g_fPDMTimeDomain);
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arm_cmplx_mag_f32(g_fPDMTimeDomain, g_fPDMMagnitudes, PDM_FFT_SIZE);
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if (PRINT_FFT_DATA)
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{
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for (uint32_t i = 0; i < PDM_FFT_SIZE / 2; i++)
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{
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Serial.printf("%f\n", g_fPDMMagnitudes[i]);
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}
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Serial.printf("END\n");
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}
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//
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// Find the frequency bin with the largest magnitude.
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//
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arm_max_f32(g_fPDMMagnitudes, PDM_FFT_SIZE / 2, &fMaxValue, &ui32MaxIndex);
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ui32LoudestFrequency = (sampleFreq * ui32MaxIndex) / PDM_FFT_SIZE;
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if (PRINT_FFT_DATA)
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{
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Serial.printf("Loudest frequency bin: %d\n", ui32MaxIndex);
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}
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Serial.printf("Loudest frequency: %d \n", ui32LoudestFrequency);
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}
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//*****************************************************************************
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//
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// Print PDM configuration data.
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//
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//*****************************************************************************
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void
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pdm_config_print(void)
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{
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uint32_t PDMClk;
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uint32_t MClkDiv;
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float frequencyUnits;
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//
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// Read the config structure to figure out what our internal clock is set
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// to.
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//
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switch (myPDM.getClockDivider())
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{
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case AM_HAL_PDM_MCLKDIV_4: MClkDiv = 4; break;
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case AM_HAL_PDM_MCLKDIV_3: MClkDiv = 3; break;
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case AM_HAL_PDM_MCLKDIV_2: MClkDiv = 2; break;
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case AM_HAL_PDM_MCLKDIV_1: MClkDiv = 1; break;
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default:
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MClkDiv = 0;
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}
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switch (myPDM.getClockSpeed())
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{
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case AM_HAL_PDM_CLK_12MHZ: PDMClk = 12000000; break;
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case AM_HAL_PDM_CLK_6MHZ: PDMClk = 6000000; break;
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case AM_HAL_PDM_CLK_3MHZ: PDMClk = 3000000; break;
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case AM_HAL_PDM_CLK_1_5MHZ: PDMClk = 1500000; break;
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case AM_HAL_PDM_CLK_750KHZ: PDMClk = 750000; break;
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case AM_HAL_PDM_CLK_375KHZ: PDMClk = 375000; break;
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case AM_HAL_PDM_CLK_187KHZ: PDMClk = 187000; break;
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default:
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PDMClk = 0;
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}
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//
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// Record the effective sample frequency. We'll need it later to print the
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// loudest frequency from the sample.
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//
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sampleFreq = (PDMClk / (MClkDiv * 2 * myPDM.getDecimationRate()));
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frequencyUnits = (float) sampleFreq / (float) PDM_FFT_SIZE;
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Serial.printf("Settings:\n");
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Serial.printf("PDM Clock (Hz): %12d\n", PDMClk);
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Serial.printf("Decimation Rate: %12d\n", myPDM.getDecimationRate());
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Serial.printf("Effective Sample Freq.: %12d\n", sampleFreq);
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Serial.printf("FFT Length: %12d\n\n", PDM_FFT_SIZE);
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Serial.printf("FFT Resolution: %15.3f Hz\n", frequencyUnits);
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}

‎libraries/PDM/src/PDM.cpp

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@@ -250,12 +250,11 @@ ap3_err_t ap3_pdm_pad_funcsel(ap3_pdm_pad_type_e type, ap3_gpio_pad_t pad, uint8
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}
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//*****************************************************************************
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//
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// Start a transaction to get some number of bytes from the PDM interface.
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//
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//*****************************************************************************
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void
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AP3_PDM::getData(uint32_t *PDMDataBuffer, uint32_t bufferSize)
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//
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// Start a transaction to get some number of bytes from the PDM interface.
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//
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//*****************************************************************************
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void AP3_PDM::getData(uint32_t *PDMDataBuffer, uint32_t bufferSize)
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{
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//
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// Configure DMA and target address.
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am_hal_pdm_fifo_flush(_PDMhandle);
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am_hal_pdm_dma_start(_PDMhandle, &sTransfer);
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myPDM._PDMdataReady = false;
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_PDMdataReady = false;
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}
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inline void AP3_PDM::pdm_isr(void)

‎libraries/PDM/src/PDM.h

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uint32_t getDecimationRate();
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bool updateConfig(am_hal_pdm_config_t newConfiguration);
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void getData(uint32_t *PDMDataBuffer, uint32_t bufferSize);
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//void begin(void);
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// void begin(unsigned long baudrate, uint16_t config);
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// void begin(unsigned long baudrate, am_hal_uart_config_t config);

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