Current Sensing Using an Arduino Motor Shield (L298N/L298P)

Current Sensing Using an Arduino Motor Shield (L298N/L298P)

This project demonstrates how to use the current sensing capabilities of an Arduino motor shield (like the L298N/L298P) to measure the current drawn by a DC motor and trigger actions based on that current. This allows you to create smarter motor control systems that can respond to varying loads, prevent overheating, and implement advanced control algorithms.

Project Ideas:

Build a robot that automatically adjusts its speed based on the load it's carrying.
Create a smart fan that increases speed as the ambient temperature rises (by sensing the increased current draw as the motor works harder).
Develop a safety mechanism that shuts off a motor if it stalls or encounters an obstacle, preventing damage.
Design a self-balancing robot that uses current sensing to detect imbalances and correct its posture.

Hardware/Components

Arduino Uno
L298N/L298P Motor Shield
DC Motor
Power Supply (for the motor)
Multimeter (optional, for verifying current readings)

Wiring Guide

%%WIRING%%

Code Explanation

The provided Arduino code utilizes the analog inputs of the Arduino to read the voltage across the current sense resistors on the motor shield. These readings are then converted into current values. The core functionality lies in these key code sections:


const double currentFactor = 2/3.3;// 3.3V per 2A (in video at 04:35)
// ... inside the loop() function ...
double currentVB = map(analogRead(currentSenseB), 0, 1024, 0, 5000)/1000;
double currentB = currentVB * currentFactor; //(in video at 04:44)
// ... similar code for currentSenseA and currentA

The currentFactor is derived from the motor shield's specifications (in this case, 3.3V corresponds to 2A). The map function scales the raw analog readings (0-1024) to voltage (0-5V). This voltage is then multiplied by the currentFactor to obtain the actual current in Amperes.

User-Configurable Parameters:

currentSenseA and currentSenseB: Analog pins connected to the current sensing outputs of the motor shield (A0 and A1 in this example). (in video at 04:44)
The threshold value (1.25 in the example) within the if statement determines the current level at which the defined action is triggered. (in video at 07:29)


if(currentB > 1.25) {
    brake('B', 1);// apply brake (in video at 07:42)
    // ... other actions
}

Live Project/Demonstration

(in video at 05:43) The video demonstrates the project in action, showing real-time current readings alongside measurements from a multimeter. This verifies the accuracy of the current sensing setup and demonstrates how the code responds to changes in motor load. The example code includes a conditional statement that applies a brake if the current exceeds a predefined threshold, illustrating a practical application of current sensing.