The closest code i could find to do this is a for somewhat the same sensor but its max read is a whole lot less than this model ...
void loop()
{
mapval= analogRead(mapsen); //Reads the MAP sensor raw value on analog port 0
boost = (mapval*(.00488)/(.022)*(0.145)-14.5); //Converts raw MAP value to PSI and accounts for atmospheric pressure
This code is for a boost gauge above , im using it as a example to follow and also to show you guys the part that puzzles me ...
I'm using this sensor to read air pressure for my air suspension in my car so i don't need to account for atmospheric pressure ... Which i guess is the -14.5 off the end i think ... I would be very grateful if someone could help me out here thanks again
if you look at page 4 you see there is a discontinuity in the graph and your formula doesn't cope with that,
Further you have rounded the floats a bit I think and given that the sensor itself has an error of ~2.5% that may easy add up to 5% or more in the end result.
So code to try and tweak
void loop()
{
// MEASUREMENT
int raw = analogRead(mapsen); //Reads the MAP sensor raw value on analog port 0
float voltage = raw * 0.004887586; // let the compiler determine how many digits it can handle
float pressure = 0.0;
// MATH
if (voltage < 4.6)
{
pressure = voltage * 700.0/4.6; // it raises 700KPA over 4.6 volt faster => pressure = voltage * 152.173913;
}
else
{
pressure = 700 + (voltage-4.6) * 100 / 0.3; // last piece raises 100KPa over 0.3 Volt. // can be optimized to p = c1 + v * c2
}
// DISPLAY
Serial.print("KPa:\t");
Serial.println(pressure, 3 );
Serial.print("PSI:\t");
Serial.println(pressure*0.145037738, 3 ); // convert to PSI
}
pressure = voltage * 700.0/4.6;
might need to be
pressure = (voltage - zeroPressureOffset) * 700.0/4.6;
4.6 is the value where the discontinuity is (imho)
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);
int mapsen = 1; // Set MAP sensor input on Analog port 0
int mapval;
void setup(){
Serial.begin(9600); // Open serial port
lcd.begin(16,2);
lcd.setCursor(0,0);
lcd.print("Air Suspension");
lcd.setCursor(0,1);
lcd.print("Gauge");
delay(1000);
lcd.clear();
}
void loop()
{
// MEASUREMENT
int raw = analogRead(mapsen); //Reads the MAP sensor raw value on analog port 0
float voltage = mapval * 0.004887586; // let the compiler determine how many digits it can handle
float pressure = 0.0;
// MATH
if (voltage < 4.6)
{
pressure = voltage * 700.0/4.6; // it raises 700KPA over 4.6 volt faster => pressure = voltage * 152.173913;
}
else
{
pressure = 700 + (voltage-4.6) * 100 / 0.3; // last piece raises 100KPa over 0.3 Volt. // can be optimized to p = c1 + v * c2
}
// DISPLAY
Serial.print(mapsen);
Serial.print("KPa:\t");
Serial.println(pressure, 3 );
Serial.print("PSI:\t");
Serial.println(pressure*0.145037738, 3 ); // convert to PSI
delay(1000);
}
I'm constantly getting "0.00" it never changes .... I think my code may be wrong
// MEASUREMENT
int raw = analogRead(mapsen); //Reads the MAP sensor raw value on analog port 0
float voltage = raw * 0.004887586; // let the compiler determine how many digits it can handle
float pressure = 0.0;
...
So I hope you guys can help me out! I'm using this same sensor.. although I probably shouldn't be, but I can't seem to get it to read correctly! The max pressure I'll be reading is about 30psi.. but It's off by about 3 or 4 psi? Here's my code.. am I missing something? Btw sorry for reviving a dead thread..
When sitting in a regular room with no load.. It reads ~18psi and it should be reading 14.7 or so right?
void showBoost()
{
float voltage = 0;
float mInput = 0;
voltage = analogRead(Boost) * 0.004887586;
if (voltage < 4.6)
{
mInput = voltage * 700.0/4.6; // it raises 700KPA over 4.6 volt faster => pressure = voltage * 152.173913;
}
else
{
mInput = 700 + (voltage-4.6) * 100 / 0.3; // last piece raises 100KPa over 0.3 Volt. // can be optimized to p = c1 + v * c2
}
mInput = mInput * 0.145037738;
//go display it
}
Here's my code.. am I missing something? Btw sorry for reviving a dead thread..