Diff: main.cpp

Revision:

4:c38f7e4e8fda

Parent:

3:1a4ad4c82046

Child:

5:bf2ed3846087

--- a/main.cpp	Tue Aug 07 13:41:11 2012 +0000
+++ b/main.cpp	Mon Aug 13 12:44:56 2012 +0000
@@ -9,24 +9,42 @@
 #include "mbed.h"
 
 DigitalOut adcCS(p8);
+DigitalOut dacCS(p14);
 DigitalOut cyc(p10);
 AnalogOut vca(p18);
-SPI adc(p5,p6,p7); //talk to ad7921
+SPI adc(p5,p6,p7); //talk to ad7921 on SSP1
+SPI dac(p11,p12,p13); //talk to ad5551 on SSP0
 Serial pc(USBTX, USBRX);
 
 
-Timer t;
 Ticker commTick;
-Ticker intTick;
+Ticker limTick;
 
-int pGain = 1;
-int iGain = 100;
+// PI variables
+int pGain = 7000;
+int iGain = 12000; 
+int ctl=0;
+int pd=0;
+int err=0;
+int out = 0;
 int integrator = 0; //the building up integrator value
 
+//control variables
+int monitor = 0; //echo to serial?
+int testDAC = 0; //stops PI, just 0-5V jumps on output
+
+
+extern "C" void mbed_reset(); 
+
+
 void serialComm(){
     char c;
     int i;
     
+    if (monitor) {
+        pc.printf("Measuring ctl=%i and pd=%i, err=%i, integrator= %i, out=%i\n",ctl,pd,err,integrator,out);
+    }
+    
     if (pc.readable()) { 
         c = pc.getc();
         pc.scanf("%i", &i);
@@ -41,6 +59,16 @@
                 if (i==0)
                     integrator = 0;
                 break;
+            case 'm':
+                monitor = i;
+                break;
+            case 't':
+                testDAC = i;
+                pc.printf("Turning on test mode... outputting 0-5 V on DAC\n");
+                break;
+            case 'z':
+                mbed_reset();
+                break;
             default:
                 pc.printf("Command not understood.\n",iGain);
                 pc.printf("Read %c and %i.\n",c,i);
@@ -50,54 +78,99 @@
 }
 
 
+void limitIntegrator() {
+    if(integrator < -(1<<14)/iGain) {
+        integrator = -(1<<14)/iGain;
+    }
+    if(integrator > (1<<14)/iGain) {
+        integrator = (1<<14)/iGain;
+    }
+}
+
 int main() {
-    int ctl=0;
-    int pd=0;
-    int err=0;
     pc.printf("mbed restarted!\n");
     
     adc.format(16,2);
-    adc.frequency(5000000); 
+    adc.frequency(5e6); 
+    dac.format(14,2);
+    dac.frequency(20e6); 
     
-    commTick.attach(&serialComm,0.5); //check serial every half second    
+    commTick.attach(&serialComm,1); //check serial every  second  
+    //limTick.attach_us(&limitIntegrator,500); //check integrator overflow every 500 us  
     cyc = 0;    
 
     while(1) {
         cyc = cyc^1; //toggle debug pin
         
+        while (testDAC) {
+            dacCS = 1;
+            dacCS = 0;
+            LPC_SSP0->DR = 0x3FFF;
+            wait_us(1000);
+            dacCS = 1;
+            dacCS = 0;
+            LPC_SSP0->DR = 0;
+            wait_us(1000);
+        } 
+        
         //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 
+        //register, do sth. else (write new output), then get the value 
         //and start the read from the other channel
        
        //begin SPI transfer
         adcCS = 0;
-        LPC_SSP1->DR = 3<<13; //initialize SSP1 transfer by writing to data register; select ch 1
+        LPC_SSP1->DR = 3<<13; //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       
-        
+        //write to DAC  
+        err = ctl - pd;   
+        integrator += err;          
+        dacCS = 0;
+        // if control is very low (probably 0V), no output and no integrator
+        // otherwise integrator overflows from stray light!
+        if (ctl < 10) { 
+            err = 0;    
+            integrator = 0;
+        }
+        out = ( (err * pGain  + integrator)>>12 ) & 0x3FFF;
+        LPC_SSP0->DR = out;
+                
         //read SPI transfer results
-        while(!(LPC_SSP1->SR & 0x04)) {}
-        pd =  LPC_SSP1->DR & 0xFFF; //last 12 bits are data
-        adcCS = 1;      
+        while(LPC_SSP1->SR & 0x10) {} //check for busy p 10   
+        pd =  LPC_SSP1->DR & 0xFFF; //last 12 bits are data    
+        wait_us(1);  //delay necessary for unknown reason    
+        adcCS = 1;
+        while(LPC_SSP0->SR & 0x10) {}
+        dacCS = 1; 
+          
+
         
         //begin transfer from other channel
         adcCS = 0;
-        LPC_SSP1->DR = 1; //initialize SSP1 transfer by writing to data register; select ch 0
+        LPC_SSP1->DR = 1; //select ch 0
         
-        err = ctl-pd; //convert to volt   
-        integrator += err*iGain;   
-        vca.write_u16( (err * pGain  + integrator)>>10 );        //analog output
-        
+        //write to DAC
+        err = ctl-pd;   
+        integrator += err*iGain;                   
+        dacCS = 0;
+        // if control is very low (probably 0V), no output and no integrator
+        // otherwise integrator overflows from stray light!
+        if (ctl < 10) { 
+            err = 0;    
+            integrator = 0;
+        }
+        out = ( (err * pGain  + integrator)>>12 ) & 0x3FFF;
+        LPC_SSP0->DR = out; 
+              
         //read SPI transfer results
-        while(!(LPC_SSP1->SR & 0x04)) {}
-        ctl = LPC_SSP1->DR & 0xFFF; //last 12 bits are data
-        adcCS = 1;      
+        while(LPC_SSP1->SR & 0x10) {}        
+        ctl = LPC_SSP1->DR & 0xFFF; //last 12 bits are data  
+        wait_us(1);  //delay necessary for unknown reason    
+        adcCS = 1;    
+        while(LPC_SSP0->SR & 0x10) {}
+        dacCS = 1;     
         
-        //pc.printf("Measuring ctl=%i and pd=%i, err=%i, integrator= %i\n",ctl,pd,err,integrator);
         
+      
     }
 }