Diff: main.cpp

Revision:

3:1a4ad4c82046

Parent:

2:6d472c554758

Child:

4:c38f7e4e8fda

--- a/main.cpp	Tue Aug 07 12:07:32 2012 +0000
+++ b/main.cpp	Tue Aug 07 13:41:11 2012 +0000
@@ -11,7 +11,7 @@
 DigitalOut adcCS(p8);
 DigitalOut cyc(p10);
 AnalogOut vca(p18);
-SPI adcSPI(p5,p6,p7); //talk to ad7921
+SPI adc(p5,p6,p7); //talk to ad7921
 Serial pc(USBTX, USBRX);
 
 
@@ -19,83 +19,85 @@
 Ticker commTick;
 Ticker intTick;
 
-float pGain = 0.5;
-float iGain = 1000.;
-float integrator = 0.; //the building up integrator value
+int pGain = 1;
+int iGain = 100;
+int integrator = 0; //the building up integrator value
 
 void serialComm(){
     char c;
-    float f;
+    int i;
     
     if (pc.readable()) { 
         c = pc.getc();
-        pc.scanf("%f", &f);
+        pc.scanf("%i", &i);
         switch (c) {
             case 'p':
-                pGain = f;   
-                pc.printf("Changed p gain to %f.\n",pGain);
+                pGain = i;   
+                pc.printf("Changed p gain to %i.\n",pGain);
                 break;
             case 'i':
-                iGain = f;   
-                pc.printf("Changed i gain to %f.\n",iGain);
-                if (f==0)
-                    integrator = 0.;
+                iGain = i;   
+                pc.printf("Changed i gain to %i.\n",iGain);
+                if (i==0)
+                    integrator = 0;
                 break;
             default:
                 pc.printf("Command not understood.\n",iGain);
-                pc.printf("Read %c and %f.\n",c,f);
+                pc.printf("Read %c and %i.\n",c,i);
                 break;
         }
     }
 }
 
-void limitIntegrator(){ 
-    if (integrator > 3.3) {
-            integrator = 3.3;
-        }
-    if (integrator < 0) {
-        integrator = 0;
-    }
-}
 
 int main() {
-    float err=0;
-    float out=0.;
     int ctl=0;
-    int pd=0; 
+    int pd=0;
+    int err=0;
     pc.printf("mbed restarted!\n");
     
-    adcSPI.format(16,2);
-    adcSPI.frequency(5000000); 
+    adc.format(16,2);
+    adc.frequency(5000000); 
     
-    commTick.attach(&serialComm,0.5); //check serial every half second  
-    intTick.attach(&limitIntegrator,0.001); //check integrator overrun every ms  
-    
-    t.start();
+    commTick.attach(&serialComm,0.5); //check serial every half second    
     cyc = 0;    
 
     while(1) {
-        cyc = cyc ^ 1; //toggle debug pin
-        //read in from AD7921 over SPI
-        adcCS = 0;
-        pd = adcSPI.write(3<<13); //select ch 1  
-        pd = (pd) & 0xFFF;
-        adcCS = 1;
+        cyc = cyc^1; //toggle debug pin
         
+        //stagger read and output
+        //The SPI read takes a long time, so start it by writing to the data
+        //register, do sth. else (create new output), then get the value 
+        //and start the read from the other channel
+       
+       //begin SPI transfer
         adcCS = 0;
-        ctl = adcSPI.write(1);       // select ch 0
-        //take the last 12 bits that carry data
-        ctl = (ctl) & 0xFFF;    
-        adcCS = 1;  
-              
-        err = ctl*3.3/4095. - pd*3.3/4095.; //convert to volt   
-        integrator += err * iGain*1.e-6 * t.read_us(); 
-        t.reset(); //reset timer to get next integration time 
-             
-        out = 1.0* err * pGain + integrator;        //analog output
-        vca.write(out); 
+        LPC_SSP1->DR = 3<<13; //initialize SSP1 transfer by writing to data register; select ch 1
+        
+        err = ctl - pd; //convert to volt   
+        integrator += err*iGain; 
+        t.reset(); //reset timer to get next integration time       
+        vca.write_u16( (err * pGain  + integrator)>>10 );        //analog output       
+        
+        //read SPI transfer results
+        while(!(LPC_SSP1->SR & 0x04)) {}
+        pd =  LPC_SSP1->DR & 0xFFF; //last 12 bits are data
+        adcCS = 1;      
         
-        //  pc.printf("Measuring ctl=%i and pd=%i, err=%f, vca is %f\n",ctl,pd,err,out);
+        //begin transfer from other channel
+        adcCS = 0;
+        LPC_SSP1->DR = 1; //initialize SSP1 transfer by writing to data register; select ch 0
+        
+        err = ctl-pd; //convert to volt   
+        integrator += err*iGain;   
+        vca.write_u16( (err * pGain  + integrator)>>10 );        //analog output
+        
+        //read SPI transfer results
+        while(!(LPC_SSP1->SR & 0x04)) {}
+        ctl = LPC_SSP1->DR & 0xFFF; //last 12 bits are data
+        adcCS = 1;      
+        
+        //pc.printf("Measuring ctl=%i and pd=%i, err=%i, integrator= %i\n",ctl,pd,err,integrator);
         
     }
 }