Restructure how getData is called/obtained.

Previously it was a bit bad: sTransfer was locally declared and used which is bad. It's now global. getData now expects the caller to provide buffer and transfers the PDM data to caller. This simplifies how the example sketches look an act.

Author: nseidle

libraries/PDM/src/PDM.cpp

@@ -24,7 +24,6 @@ SOFTWARE.
 AP3_PDM *ap3_pdm_handle = 0;
 am_hal_pdm_transfer_t sTransfer;
 
-//Temp
 #define internalPDMDataBufferSize 4096 //Default is array of 4096 * 32bit
 uint32_t internalPDMDataBuffer[internalPDMDataBufferSize];
 
@@ -215,6 +214,8 @@ bool AP3_PDM::updateConfig(am_hal_pdm_config_t newConfiguration)
     _PDMconfig = newConfiguration;
     ap3_err_t retval = (ap3_err_t)am_hal_pdm_configure(_PDMhandle, &_PDMconfig);
 
+    am_hal_pdm_enable(_PDMhandle); //Reenable after changes
+
     if (retval != AP3_OK)
     {
         return false;
@@ -267,18 +268,23 @@ ap3_err_t ap3_pdm_pad_funcsel(ap3_pdm_pad_type_e type, ap3_gpio_pad_t pad, uint8
 
 //*****************************************************************************
 //
-// Start a transaction to get some number of bytes from the PDM interface.
+// Read PDM data from internal buffer
+// Returns number of bytes read.
 //
 //*****************************************************************************
-void AP3_PDM::getData(uint32_t *externalBuffer, uint32_t bufferSize)
+uint32_t AP3_PDM::getData(uint32_t *externalBuffer, uint32_t bufferSize)
 {
     if (_PDMdataReady)
     {
+        if (bufferSize > internalPDMDataBufferSize)
+            bufferSize = internalPDMDataBufferSize;
+
         noInterrupts();
 
         //Move data from internal buffer to external caller
         for (int x = 0; x < bufferSize; x++)
-            externalBuffer[x] = internalPDMDataBuffer[x]; //Not clear, PDMDataBuffer is bufferSize * 2, do we need just the one left byte vs one right byte?
+            externalBuffer[x] = internalPDMDataBuffer[x];
+
         interrupts();
     }
     _PDMdataReady = false;
@@ -297,23 +303,16 @@ inline void AP3_PDM::pdm_isr(void)
     am_hal_pdm_interrupt_status_get(_PDMhandle, &ui32Status, true);
     am_hal_pdm_interrupt_clear(_PDMhandle, ui32Status);
 
-    //
-    // Once our DMA transaction completes, we will disable the PDM and send a
-    // flag back down to the main routine. Disabling the PDM is only necessary
-    // because this example only implemented a single buffer for storing FFT
-    // data. More complex programs could use a system of multiple buffers to
-    // allow the CPU to run the FFT in one buffer while the DMA pulls PCM data
-    // into another buffer.
-    //
     if (ui32Status & AM_HAL_PDM_INT_DCMP)
     {
         if (_PDMdataReady == true)
-            Serial.println("Buffer overrun!");
-        else
         {
-            //New data has been loaded into internalPDMDataBuffer
-            _PDMdataReady = true;
+            //If flag has not previously been cleared, we're overrun
+            //Serial.println("Buffer overrun!");
         }
+
+        //New data has been loaded into internalPDMDataBuffer
+        _PDMdataReady = true;
     }
 }
 

libraries/PDM/src/PDM.h

@@ -114,7 +114,7 @@ class AP3_PDM
 
     bool updateConfig(am_hal_pdm_config_t newConfiguration);
 
-    void getData(uint32_t *externalBuffer, uint32_t bufferSize);
+    uint32_t getData(uint32_t *externalBuffer, uint32_t bufferSize);
 
     void pdm_isr(void);