/*
* Lupo to Insight Engine Coolant Temperature (ECT) Conversion
* by Jake Staub (1/9/09)
*
* Takes the Lupo ECT voltage signal, converts it to a temperature,
* then turns the temperature into the required Insight resistance
* value.
* Lupo temp(volt) = a*volt^3 + b*volt^2 + c*x + d.
* Insight res(temp) = e*f^(g*temp).
*/
int ECTvolt = 2; // Lupo IAT sensor input pin
int val = 0; // variable to store the ADC value coming from the Lupo ECT sensor
float volt = 0; // variable to store Lupo voltage value
int fractional; // variable to store fractional Lupo voltage value
int temp = 0; // variable to store Lupo calculated temperature value
int res = 0; // variable to strore Insight calculated resistance value
float a = -5.77; // constant derived from Lupo temp vs. voltage curve fit
int b = 48; // constant derived from Lupo temp vs. voltage curve fit
int c = -171; // constant derived from Lupo temp vs. voltage curve fit
int d = 345; // constant derived from Lupo temp vs. voltage curve fit
int e = 9272; // constant derived from Insight res vs. temp curve fit
float f = 2.718; // natural number
float g = -0.0182; // constant derived from Insight res vs. temp curve fit
void setup() {
Serial.begin(9600); // opens serial port for debugging
}
void loop() {
val = analogRead(ECTvolt); // reads the value from the sensor
volt = val / 204.8; // converts digital val to analog volt
val = val / 205; // converts digital val to analog val
fractional = (volt - val)*1000; // calculates decimal voltage value
Serial.print("volt = "); // prints "volt = "
Serial.print(val); // prints integer volt value
Serial.print("."); // prints "."
Serial.println(fractional); // prints decimal volt value
delay(3000); // 3 second delay (3000 ms)
temp = a*pow(volt,3) + b*pow(volt,2) +
c*volt + d; // Lupo temperature as a function of voltage
Serial.print("temp = "); // prints "temp = "
Serial.println(temp); // prints analog temperature value
delay(3000); // 3 second delay (3000 ms)
res = e*pow(f,(g*temp)); // Insight resistance as a function of temperature
if (res < 30) // resistance limit
{res = 30;}
Serial.print("res = "); // prints "res = "
Serial.println(res); // prints analog resistance value
delay(3000); // 3 second delay (3000 ms)
}
