INA169 Breakout Board Hookup Guide
Example Code
Open the Arduino program and paste the following code into the sketch:
/* 11-14-2013 SparkFun Electronics 2013 Shawn Hymel This code is public domain but you buy me a beer if you use this and we meet someday (Beerware license). Description: This sketch shows how to use the SparkFun INA169 Breakout Board. As current passes through the shunt resistor (Rs), a voltage is generated at the Vout pin. Use an analog read and some math to determine the current. The current value is displayed through the Serial Monitor. Hardware connections: Uno Pin INA169 Board Function +5V VCC Power supply GND GND Ground A0 VOUT Analog voltage measurement VIN+ and VIN- need to be connected inline with the positive DC power rail of a load (e.g. an Arduino, an LED, etc.). */ // Constants const int SENSOR_PIN = A0; // Input pin for measuring Vout const int RS = 10; // Shunt resistor value (in ohms) const int VOLTAGE_REF = 5; // Reference voltage for analog read // Global Variables float sensorValue; // Variable to store value from analog read float current; // Calculated current value void setup() { // Initialize serial monitor Serial.begin(9600); } void loop() { // Read a value from the INA169 board sensorValue = analogRead(SENSOR_PIN); // Remap the ADC value into a voltage number (5V reference) sensorValue = (sensorValue * VOLTAGE_REF) / 1023; // Follow the equation given by the INA169 datasheet to // determine the current flowing through RS. Assume RL = 10k // Is = (Vout x 1k) / (RS x RL) current = sensorValue / (10 * RS); // Output value (in amps) to the serial monitor to 3 decimal // places Serial.print(current, 3); Serial.println(" A"); // Delay program for a few milliseconds delay(500); }
Plug in the Arduino and upload the code. You should see the LED light up as soon as you apply power.
Select the appropriate board (Arduino Uno in this case) from Tools->Board and the correct COM port from Tools->Serial Port. Click the upload button, and wait for the program to be compiled and uploaded to the Arduino. Open the Serial Monitor from Tools->Serial Monitor and you should see current measurements being printed.
If we want to verify this reading, we can use a multimeter to measure the voltage across the 330Ω resistor. You should see around 3V across the resistor. Using Ohm's Law, we can calculate the current flowing through the resistor and LED is 0.00909 A, which matches the reading from the INA169.