Diff: main.cpp

Revision:

0:ff0b6f6ddb23

Child:

1:5f34e59f97f7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Nov 11 19:16:20 2015 +0000
@@ -0,0 +1,112 @@
+#include "mbed.h"
+
+// Serial pc(SERIAL_TX, SERIAL_RX); // for debbug
+ 
+// Peripherials
+DigitalIn mybutton(USER_BUTTON);
+DigitalOut myled(LED1);
+AnalogIn AudioIn(A0);
+AnalogOut AudioOut(A2);
+
+// Define Ticker
+Ticker Audio_Sample_Ticker;
+
+// Audio Buffer
+#define BUFFERSIZE 30000 // Sample rate 10 Khz, 3 sec record 30*10^3 samples
+uint16_t ABuffer[BUFFERSIZE]={0};
+// variables to store buffer position and lenght
+uint32_t BufferEnd=0;
+uint32_t Buffer_i=0;
+bool RecordFull=0;
+// Variable to store button state
+bool ButtonState=0;
+bool LastButtonState=0;
+
+volatile bool Audio_Sample_Flag=0;
+
+// Filter sound HPF to remove dc for amplification
+// Simple First order filter
+float AudioSignal=0;
+float AHPF=0.99f; 
+
+float LastY=0;
+float CurY=0;
+float LastU=0;
+float CurU=0;
+
+// Ticker function
+void Audio_Sample() {
+    Audio_Sample_Flag=1;;
+}
+ 
+int main() { // setup loop
+  
+  // attach Ticker object
+  Audio_Sample_Ticker.attach_us(&Audio_Sample, 100); // create 10Khz Ticker
+  
+  while(1) { // infinite loop
+    if (Audio_Sample_Flag){
+        Audio_Sample_Flag=0;
+        LastButtonState=ButtonState;
+        ButtonState=mybutton.read();
+        
+            // Record sample and apply filter
+            // Buffer variables
+            LastU=CurU;
+            CurU=AudioIn.read();
+            LastY=CurY;
+            
+            // Simple Filter HPF
+            CurY=AHPF*(LastY+CurU-LastU);
+            
+            // Amplify, add dc offset and add to buffer;
+            AudioSignal=CurY*3.0f+0.5f;//*10.0f+0.5f);
+            if (AudioSignal>1){
+                AudioSignal=1;
+            }else if (AudioSignal<0){
+                AudioSignal=0;
+            }
+        
+        if ((!ButtonState)&&(!RecordFull) ){ // Button is pressed and record is not full
+          myled.write(1); // LED On
+          if (LastButtonState){ // first sample
+              Buffer_i=0;
+              // Re-set Ticker object
+              Audio_Sample_Ticker.attach_us(&Audio_Sample, 100); // create 10Khz Ticker
+          }
+          // Record samples
+           //ABuffer[Buffer_i]=AudioIn.read_u16();
+            
+            AudioSignal=AudioSignal*0xFFFF; // scale to 16 bit (aligned to left apparently, wasted an hour on that one)
+            ABuffer[Buffer_i]=(uint16_t)AudioSignal; // Store to buffer;
+            
+            //pc.printf("%d \r\n",ABuffer[Buffer_i]); // debug check/
+            //AudioOut.write_u16(ABuffer[Buffer_i]); // Debug output
+            
+          BufferEnd=Buffer_i;
+          Buffer_i++;
+          if (Buffer_i==BUFFERSIZE){ // buffer full
+              RecordFull=1;
+              Buffer_i=0; 
+              myled.write(0); // LED Off // record off
+          }
+        
+        }else if (ButtonState) { //Button is unpressed
+          if (!LastButtonState){ // first sample
+              // Re-set Ticker object
+              Audio_Sample_Ticker.attach_us(&Audio_Sample, 75); // create 10Khz Ticker
+           //   Buffer_i=0;
+          }
+          myled.write(0); // LED Off
+          // Play Recorded audio
+          RecordFull=0;
+           if (Buffer_i>BufferEnd){ // Replay record
+              Buffer_i=0;
+           }
+           AudioOut.write_u16(ABuffer[Buffer_i]);
+           Buffer_i++;
+        }
+    }     
+  }
+}
+ 
\ No newline at end of file