Hi All,
This is what I ended up doing...
5K between Gnd & D1
20k between Vin & D1
/* Read voltage divider
* Reads the voltage divider to calculate a battery voltage
* This software has no warranty, real or implied and is free to distribute and modify
*/
int batMonPin = A1; // input pin for the divider
int val = 0; // variable for the A/D value
float pinVoltage = 0; // variable to hold the calculated voltage
float batteryVoltage = 0;
float ratio = 2.316; // Change this to match the MEASURED ration of the circuit
void setup() {
Serial.begin(9600); // open the serial port at 9600 baud
}
void loop() {
val = analogRead(batMonPin); // read the voltage on the divider
pinVoltage = val * 0.00473; // Calculate the voltage on the A/D pin
// A reading of 1 for the A/D = 0.0048mV
// if we multiply the A/D reading by 0.00488 then
// we get the voltage on the pin.
batteryVoltage = pinVoltage * 5.075; // Use the ratio calculated for the voltage divider
// to calculate the battery voltage
Serial.print("Voltage: ");
Serial.println(batteryVoltage);
delay(1000); // Slow it down
}
I just played with the ratio until I got the correct reading.
Steve...