Final version of ADC.c

Labware/Lab14_MeasurementOfDistance/ADC.c

@@ -31,7 +31,23 @@
 // SS3 1st sample source:  channel 1
 // SS3 interrupts: enabled but not promoted to controller
 void ADC0_Init(void){ 
-  
+	   volatile unsigned long delay;
+  SYSCTL_RCGC2_R |= 0x00000010;   // 1) activate clock for Port E
+  delay = SYSCTL_RCGC2_R;         //    allow time for clock to stabilize
+  GPIO_PORTE_DIR_R &= ~0x04;      // 2) make PE2 input
+  GPIO_PORTE_AFSEL_R |= 0x04;     // 3) enable alternate function on PE2
+  GPIO_PORTE_DEN_R &= ~0x04;      // 4) disable digital I/O on PE2
+  GPIO_PORTE_AMSEL_R |= 0x04;     // 5) enable analog function on PE2
+  SYSCTL_RCGC0_R |= 0x00010000;   // 6) activate ADC0
+  delay = SYSCTL_RCGC2_R;        
+  SYSCTL_RCGC0_R &= ~0x00000300;  // 7) configure for 125K
+  ADC0_SSPRI_R = 0x0123;          // 8) Sequencer 3 is highest priority
+  ADC0_ACTSS_R &= ~0x0008;        // 9) disable sample sequencer 3
+  ADC0_EMUX_R &= ~0xF000;         // 10) seq3 is software trigger
+  ADC0_SSMUX3_R &= ~0x000F;       // 11) clear SS3 field
+  ADC0_SSMUX3_R += 1;             //    set channel Ain1 (PE2)
+  ADC0_SSCTL3_R = 0x0006;         // 12) no TS0 D0, yes IE0 END0
+  ADC0_ACTSS_R |= 0x0008;         // 13) enable sample sequencer 3
 }
 
 
@@ -40,5 +56,10 @@ void ADC0_Init(void){
 // Input: none
 // Output: 12-bit result of ADC conversion
 unsigned long ADC0_In(void){  
-  return 0; // replace this line with proper code
+  unsigned long result;
+  ADC0_PSSI_R = 0x0008;            // 1) initiate SS3
+  while((ADC0_RIS_R&0x08)==0){};   // 2) wait for conversion done
+	result = ADC0_SSFIFO3_R&0xFFF;   // 3) read result
+	ADC0_ISC_R = 0x0008;             // 4) acknowledge completion
+  return result;
 }