fix demo to work with CPB

Author: ladyada

libraries/PDM/examples/PDMSerialPlotter/PDMSerialPlotter.ino

@@ -12,7 +12,7 @@
 
 // The default Circuit Playground Bluefruit pins 
 // data pin, clock pin, power pin (-1 if not used)
-PDMClass PDM(33, 34, -1);
+PDMClass PDM(24, 25, -1);
 
 // buffer to read samples into, each sample is 16-bits
 short sampleBuffer[256];
@@ -41,13 +41,13 @@ void setup() {
 
 void loop() {
   // wait for samples to be read
-  if (samplesRead) {
+  PDM.IrqHandler();
 
+  if (samplesRead) {
     // print samples to the serial monitor or plotter
     for (int i = 0; i < samplesRead; i++) {
       Serial.println(sampleBuffer[i]);
     }
-
     // clear the read count
     samplesRead = 0;
   }
@@ -62,4 +62,4 @@ void onPDMdata() {
 
   // 16-bit, 2 bytes per sample
   samplesRead = bytesAvailable / 2;
-}
+}