Diff: main.cpp

Revision:

0:cf938939cb77

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Oct 13 09:40:21 2017 +0000
@@ -0,0 +1,55 @@
+#include "mbed.h"
+#include "main.h"
+
+#include "BP_4KHz_Fc_35KHz_Fs_5N.h"
+
+//MBED Class Instances follows
+DigitalOut SampLED(LED1);              //Digital Output  (GREEN LED is PB_3, D13 You can use an Oscilloscope on This pin to confirm sample rate)
+
+AnalogIn  Ain(PA_1);                    //Analog Input (Signal Input 0 to +3 Volts)
+AnalogOut Aout(PA_4);                   //Analog Output (Signal Input 0 to +3 Volts)
+
+Ticker sample_timer;
+
+//Ticker routine PROTOTYPE to service samples from Analogue IP and port to Analogue Output
+void sampler(void);
+
+int main() {
+   
+    float sample_rate=(1.0/Fs)*1000000.0; //Calculate the number of uS required for a Frequency Sampling Rate
+                                          //Fs held in init.h
+    sample_timer.attach_us(&sampler,(int)sample_rate);
+                                          //Ticker Instance serviced by routine at a repeat rate in microseconds
+  
+    while(1) {
+          sleep();
+    }
+}
+
+//Ticker routine to service samples from Analogue IP and port to Analogue Output
+void sampler(void)
+{
+    SampLED = ON;       //LED Indicates start of sampling
+
+    xn=Ain;               //Input ADC. N.B. ADC in MBED is 0.0 to 1.0 float!!!!!!
+
+    centreTap = xn*b0 + xnm1*b1 + xnm2*b2 + xnm3*b3 + xnm4*b4;  //IIR Filter
+    yn = centreTap*a0 - a1*ynm1 - a2*ynm2  - a3*ynm3 - a4*ynm4; //Result in yn
+  
+    Aout=yn+0.5f;       //Output resultant to DAC. Again MBED uses 0.0 to 1.0 float!!!!!! and Offset to give 0 to 3V3 range
+  
+    //THESE NEED TO BE LOADED IN THIS ORDER OTHERWISE ALL xnm VALUES WILL BECOME THE SAME AS xn
+    xnm4 = xnm3;
+    xnm3 = xnm2;
+    xnm2 = xnm1;
+    xnm1 = xn;  
+    
+    //THESE NEED TO BE LOADED IN THIS ORDER OTHERWISE ALL ynm VALUES WILL BECOME THE SAME AS yn
+    ynm4 = ynm3;
+    ynm3 = ynm2;
+    ynm2 = ynm1;
+    ynm1 = yn;
+
+    SampLED = OFF;      //LED Indicates end of sampling
+}
+