Merge pull request #44 from sparkfun/PDM

PDM library with examples

Author: oclyke

cores/arduino/am_sdk_ap3/CMSIS/ARM/Include/arm_math.h

@@ -33,7 +33,7 @@ extern "C"
 #ifdef OVERFLOW
 #define ARDUINO_REDEFINE_OVERFLOW OVERFLOW
 #undef OVERFLOW
-#warning "OVERFLOW is defined already... trying to save it, include Apollo3 headers, then restore it"
+// #warning "OVERFLOW is defined already... trying to save it, include Apollo3 headers, then restore it"
 #endif
 
 // Include Apollo headers
@@ -44,7 +44,7 @@ extern "C"
 #include <math.h> //Gets us pow()
 
 #ifdef ARDUINO_REDEFINE_OVERFLOW
-#warning "restoring OVERFLOW from value in ARDUINO_REDEFINE_OVERFLOW"
+// #warning "restoring OVERFLOW from value in ARDUINO_REDEFINE_OVERFLOW"
 #define OVERFLOW ARDUINO_REDEFINE_OVERFLOW
 #undef ARDUINO_REDEFINE_OVERFLOW
 #endif

cores/arduino/ard_sup/Arduino.h

@@ -0,0 +1,186 @@
+/* Author: Nathan Seidle
+  Created: July 24, 2019
+  License: MIT. See SparkFun Arduino Apollo3 Project for more information
+
+  This example demonstrates how to use the pulse density microphone (PDM) on Artemis boards.
+  This library and example are heavily based on the Apollo3 pdm_fft example.
+*/
+
+//Global variables needed for PDM library
+#define pdmDataBufferSize 4096 //Default is array of 4096 * 32bit
+uint32_t pdmDataBuffer[pdmDataBufferSize];
+
+//Global variables needed for the FFT in this sketch
+float g_fPDMTimeDomain[pdmDataBufferSize * 2];
+float g_fPDMFrequencyDomain[pdmDataBufferSize * 2];
+float g_fPDMMagnitudes[pdmDataBufferSize * 2];
+uint32_t sampleFreq;
+
+//Enable these defines for additional debug printing
+#define PRINT_PDM_DATA 0
+#define PRINT_FFT_DATA 0
+
+#include <PDM.h> //Include PDM library included with the Aruino_Apollo3 core
+AP3_PDM myPDM; //Create instance of PDM class
+
+//Math library needed for FFT
+#define ARM_MATH_CM4
+#include <arm_math.h>
+
+void setup()
+{
+  Serial.begin(9600);
+  Serial.println("SparkFun PDM Example");
+
+  if (myPDM.begin() == false) // Turn on PDM with default settings
+  {
+    Serial.println("PDM Init failed. Are you sure these pins are PDM capable?");
+    while (1);
+  }
+  Serial.println("PDM Initialized");
+
+  printPDMConfig();
+    
+  myPDM.getData(pdmDataBuffer, pdmDataBufferSize); //This clears the current PDM FIFO and starts DMA
+}
+
+void loop()
+{
+  noInterrupts();
+
+  if (myPDM.available())
+  {
+    printLoudest();
+
+    while (PRINT_PDM_DATA || PRINT_FFT_DATA);
+
+    // Start converting the next set of PCM samples.
+    myPDM.getData(pdmDataBuffer, pdmDataBufferSize);
+  }
+
+  // Go to Deep Sleep until the PDM ISR or other ISR wakes us.
+  am_hal_sysctrl_sleep(AM_HAL_SYSCTRL_SLEEP_DEEP);
+
+  interrupts();
+}
+
+//*****************************************************************************
+//
+// Analyze and print frequency data.
+//
+//*****************************************************************************
+void printLoudest(void)
+{
+  float fMaxValue;
+  uint32_t ui32MaxIndex;
+  int16_t *pi16PDMData = (int16_t *) pdmDataBuffer;
+  uint32_t ui32LoudestFrequency;
+
+  //
+  // Convert the PDM samples to floats, and arrange them in the format
+  // required by the FFT function.
+  //
+  for (uint32_t i = 0; i < pdmDataBufferSize; i++)
+  {
+    if (PRINT_PDM_DATA)
+    {
+      Serial.printf("%d\n", pi16PDMData[i]);
+    }
+
+    g_fPDMTimeDomain[2 * i] = pi16PDMData[i] / 1.0;
+    g_fPDMTimeDomain[2 * i + 1] = 0.0;
+  }
+
+  if (PRINT_PDM_DATA)
+  {
+    Serial.printf("END\n");
+  }
+
+  //
+  // Perform the FFT.
+  //
+  arm_cfft_radix4_instance_f32 S;
+  arm_cfft_radix4_init_f32(&S, pdmDataBufferSize, 0, 1);
+  arm_cfft_radix4_f32(&S, g_fPDMTimeDomain);
+  arm_cmplx_mag_f32(g_fPDMTimeDomain, g_fPDMMagnitudes, pdmDataBufferSize);
+
+  if (PRINT_FFT_DATA)
+  {
+    for (uint32_t i = 0; i < pdmDataBufferSize / 2; i++)
+    {
+      Serial.printf("%f\n", g_fPDMMagnitudes[i]);
+    }
+
+    Serial.printf("END\n");
+  }
+
+  //
+  // Find the frequency bin with the largest magnitude.
+  //
+  arm_max_f32(g_fPDMMagnitudes, pdmDataBufferSize / 2, &fMaxValue, &ui32MaxIndex);
+
+  ui32LoudestFrequency = (sampleFreq * ui32MaxIndex) / pdmDataBufferSize;
+
+  if (PRINT_FFT_DATA)
+  {
+    Serial.printf("Loudest frequency bin: %d\n", ui32MaxIndex);
+  }
+
+  Serial.printf("Loudest frequency: %d         \n", ui32LoudestFrequency);
+}
+
+//*****************************************************************************
+//
+// Print PDM configuration data.
+//
+//*****************************************************************************
+void printPDMConfig(void)
+{
+  uint32_t PDMClk;
+  uint32_t MClkDiv;
+  float frequencyUnits;
+
+  //
+  // Read the config structure to figure out what our internal clock is set
+  // to.
+  //
+  switch (myPDM.getClockDivider())
+  {
+    case AM_HAL_PDM_MCLKDIV_4: MClkDiv = 4; break;
+    case AM_HAL_PDM_MCLKDIV_3: MClkDiv = 3; break;
+    case AM_HAL_PDM_MCLKDIV_2: MClkDiv = 2; break;
+    case AM_HAL_PDM_MCLKDIV_1: MClkDiv = 1; break;
+
+    default:
+      MClkDiv = 0;
+  }
+
+  switch (myPDM.getClockSpeed())
+  {
+    case AM_HAL_PDM_CLK_12MHZ:  PDMClk = 12000000; break;
+    case AM_HAL_PDM_CLK_6MHZ:   PDMClk =  6000000; break;
+    case AM_HAL_PDM_CLK_3MHZ:   PDMClk =  3000000; break;
+    case AM_HAL_PDM_CLK_1_5MHZ: PDMClk =  1500000; break;
+    case AM_HAL_PDM_CLK_750KHZ: PDMClk =   750000; break;
+    case AM_HAL_PDM_CLK_375KHZ: PDMClk =   375000; break;
+    case AM_HAL_PDM_CLK_187KHZ: PDMClk =   187000; break;
+
+    default:
+      PDMClk = 0;
+  }
+
+  //
+  // Record the effective sample frequency. We'll need it later to print the
+  // loudest frequency from the sample.
+  //
+  sampleFreq = (PDMClk / (MClkDiv * 2 * myPDM.getDecimationRate()));
+
+  frequencyUnits = (float) sampleFreq / (float) pdmDataBufferSize;
+
+  Serial.printf("Settings:\n");
+  Serial.printf("PDM Clock (Hz):         %12d\n", PDMClk);
+  Serial.printf("Decimation Rate:        %12d\n", myPDM.getDecimationRate());
+  Serial.printf("Effective Sample Freq.: %12d\n", sampleFreq);
+  Serial.printf("FFT Length:             %12d\n\n", pdmDataBufferSize);
+  Serial.printf("FFT Resolution: %15.3f Hz\n", frequencyUnits);
+}