Added math to calculate flow rate

board/adc/adc.c

@@ -1,27 +1,28 @@
 #include "../driver/adc.h"
 
-
 void adcInit(void) { 
   /* Enable ADC */
   ADCSRA = (1 << ADEN) | (1 << ADSC);
-  /* Left Adjust Results */
-  //ADCSRB = (1 << ADLAR);
-  //printf("ADC has started\n");
 }
 
-/*
-void getPSI(void) {
+
+void getPascal(void) {
+  while(ADCSRA & (1 << ADSC));
   ADCSRA |= (1 << ADSC); // Start ADC conversion 
-  float rawPresureData = ADCH; // Max is 8bit value	
-  printf("PSI: %.2f", (rawPresureData / 255.0) * 14.5);
-  delay_ms(100);
+  int ten_bit_value = ADCL + (ADCH * 256);
+  kiloPascal = ten_bit_value / SENSITIVITY;
+  pascal = fabs(kiloPascal - 0.98) * 1000.00;
+  printf("Pa: %.2f\n", pascal);
+  _delay_ms(250);
 }
 
-uint8_t adcStart(void) {
+void getFlowRate(void) {
+  while(ADCSRA & (1 << ADSC));
   ADCSRA |= (1 << ADSC); // Start ADC conversion 
-  loop_until_bit_is_clear(ADCSRA, ADSC); 
-  uint8_t rawPresureData = ADCH; // Max is 8bit value
-  
-  return rawPresureData;
+  int ten_bit_value = ADCL + (ADCH * 256);
+  kiloPascal = ten_bit_value / SENSITIVITY;
+  pascal = fabs(kiloPascal - 0.98) * 1000.00;   
+  flow = sqrt(pascal / 33); // Bernoulli's equation
+  printf("Flow rate %.2f cm/s\n", flow); 
+  _delay_ms(250);
 }
-*/

board/driver/adc.h

@@ -1,7 +1,11 @@
+#include <stdio.h>
 #include <avr/io.h>
-#include <stdint.h>
-#define OFFSET 44 
+#include <math.h>
+#include <util/delay.h>
+#define SENSITIVITY 44.00
 
+float kiloPascal, pascal;
+float flow;
 void adcInit(void);
-//void getPSI(void);
-//uint8_t adcStart(void);
+void getPascal(void);
+void getFlowRate(void);

board/main.c

@@ -4,13 +4,10 @@
 static FILE mystdout = FDEV_SETUP_STREAM(print, NULL, _FDEV_SETUP_RW);
 
 int main(void) {  
-    adcInit();
-    usartInit(MYUBRR);
+    adcInit(); 
+	usartInit(MYUBRR);
     stdout = &mystdout;
     while(1) {	
-	while(ADCSRA & (1 << ADSC));
-  	ADCSRA |= (1 << ADSC); // Start ADC conversion 
-	// TODO: Must subtract ADCH from offset.
-	printf("PSI: %.2f\n", (ADCH / 255.0) * 14.5);
-	}
+	     getFlowRate();
+    }
 }