Alright, here is the final code
#include <LiquidCrystal.h>
#include <math.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
// the setup routine runs once when you press reset:
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
pinMode(A0, INPUT); //A0 is set as input
#define PRESSURE_SENSOR A0;
lcd.begin(16, 2);
lcd.print("MKS Instruments");
lcd.setCursor(0, 1);
lcd.print("IMT Cold Cathode");
delay(6500);
lcd.clear();
lcd.print("Gauge Pressure:");
}
// the loop routine runs over and over again forever:
void loop() {
float v = analogRead(A0); //v is input voltage set as floating point unit on analogRead
v = v * 10.0 / 1024; //v is 0-5v divider voltage measured from 0 to 1024 calculated to 0v to 10v scale
float p = pow(10, v - 11.000); //p is pressure in torr, which is represented by k in the equation [P=10^(v-k)] which is-
// -11.000 (K = 11.000 for Torr, 10.875 for mbar, 8.000 for microns, 8.875 for Pascal)
Serial.print(v);
char pressureE[8];
dtostre(p, pressureE, 1, 0); // scientific format with 1 decimal places
lcd.setCursor(0, 1);
lcd.print(pressureE);
lcd.print(" Torr");
}
I uploaded it to my test platform and booted it up, connecting A0 to the 5v aref and gnd respectively. GND shows 1.0e-11 torr, and the 5v shows 9.8e-02, (close enough) seems pretty spot on to me! Curious though, is there any reason it is reading the top of the range slightly off? Is that just an accuracy thing?
Also, you have been a massive help, I got majorly hung up on this for some reason even though it seems it was right under my nose lol. When I first started this project it seemed so daunting. This is my first program BTW! :3