Merge pull request #677 from adafruit/fix-pdm

fix pdm issue when bluefruit is enabled

Author: hathach

libraries/PDM/examples/PDMSerialPlotter/PDMSerialPlotter.ino

@@ -18,7 +18,7 @@ volatile int samplesRead;
 
 void setup() {
   Serial.begin(9600);
-  while (!Serial);
+  while (!Serial) yield();
 
   // configure the data receive callback
   PDM.onReceive(onPDMdata);
@@ -31,7 +31,7 @@ void setup() {
   // - a 16 kHz sample rate
   if (!PDM.begin(1, 16000)) {
     Serial.println("Failed to start PDM!");
-    while (1);
+    while (1) yield();
   }
 }
 

libraries/PDM/src/PDM.cpp

@@ -58,9 +58,29 @@ int PDMClass::begin(int channels, long sampleRate)
   _channels = channels;
 
   // Enable high frequency oscillator if not already enabled
-  if (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) {
-    NRF_CLOCK->TASKS_HFCLKSTART    = 1;
-    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) { }
+  uint8_t sd_en = 0;
+  sd_softdevice_is_enabled(&sd_en);
+
+  if (sd_en)
+  {
+    uint32_t is_running;
+    sd_clock_hfclk_is_running(&is_running);
+
+    if (!is_running) {
+      sd_clock_hfclk_request();
+
+      while(!is_running) {
+        yield();
+        sd_clock_hfclk_is_running(&is_running);
+      }
+    }
+  }
+  else
+  {
+    if (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) {
+      NRF_CLOCK->TASKS_HFCLKSTART    = 1;
+      while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0) yield();
+    }
   }
 
   // configure the sample rate and channels