KY-033 Line Tracking Sensor Module
The KY-033 is a line tracking sensor module that detects light-reflective and light-absorbing surfaces using infrared technology. It provides a digital output signal upon detecting a line, making it suitable for applications like robotic navigation and line-following projects.
KY-033 pinout
The KY-033 is a 3-pin line tracking sensor module:
| Pin | Type | Description | Notes |
|---|---|---|---|
| GND | Power | Ground connection | |
| VCC | Power | Power supply | 3.3V or 5V |
| S | Communication | Signal output | LOW when line detected, HIGH over white surface |
Interface: Digital line detection
Sensor: IR LED emitter + phototransistor receiver pair
Signal: Active low - S pin LOW when over black line, HIGH over white/reflective surface
Power: 3.3V to 5V operation
Detection Height: Optimal 2-10mm above surface
Adjustment: Onboard potentiometer for sensitivity tuning
LED Indicators: Power LED and detection status LED
Applications: Line-following robots, automated guided vehicles (AGV), track detection
Wiring the KY-033 to ESP32
To interface the KY-033 with an ESP32 for line tracking:
| KY-033 pin | ESP32 pin | Purpose |
|---|---|---|
| GND | GND | Ground |
| VCC | 3.3V or 5V | Power supply |
| S | GPIO16 | Digital input (any GPIO) |
Detection Logic: S reads LOW on black line, HIGH on white/reflective surface
Calibration: Adjust potentiometer for optimal contrast detection on your surface
Mounting Height: Keep sensor 2-10mm above surface for best performance
Pull-up: Internal pull-up recommended for stable HIGH state
Multi-Sensor Arrays: Use multiple sensors (3-5) for robust line following
Ambient Light: Works best indoors - bright sunlight can interfere
Power LED: Always on when powered
Status LED: Lights when line (dark surface) detected
KY-033 code examples
int linetracking = 16; // KY-033 signal pin (GPIO16, matches the wiring above)
int value;
void setup() {
pinMode(linetracking, INPUT); // The module has its own output driver
Serial.begin(115200);
Serial.println("KY-033 Linetracking");
}
void loop() {
value = digitalRead(linetracking);
if (value == HIGH) {
Serial.println("Line recognized");
delay(200); // 200 ms break
}
}This Arduino code initializes the sensor input pin and serial communication. In the loop, it reads the sensor value and prints "Line recognized" to the serial monitor when a line is detected. A 200 ms delay is added to debounce the sensor readings.
#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"
#define SENSOR_PIN GPIO_NUM_16
void app_main(void) {
gpio_config_t io_conf = {
.intr_type = GPIO_INTR_DISABLE,
.mode = GPIO_MODE_INPUT,
.pin_bit_mask = (1ULL << SENSOR_PIN),
.pull_up_en = GPIO_PULLUP_ENABLE
};
gpio_config(&io_conf);
printf("KY-033 Line Tracking Sensor Test\n");
while (1) {
int sensor_value = gpio_get_level(SENSOR_PIN);
if (sensor_value == 1) { // Line detected
printf("Line recognized\n");
} else {
printf("No line detected\n");
}
vTaskDelay(pdMS_TO_TICKS(500));
}
}This ESP-IDF code configures GPIO16 as an input with a pull-up resistor. It continuously reads the sensor's state and prints "Line recognized" or "No line detected" to the console based on the sensor's output.
binary_sensor:
- platform: gpio
pin:
number: GPIO16
mode: INPUT_PULLUP
inverted: true
name: "KY-033 Line Tracking Sensor"
device_class: motion
on_press:
then:
- logger.log: "Line detected"
on_release:
then:
- logger.log: "No line detected"The tracker's output is read on GPIO16 with the internal pull-up; inverted: true on the pin makes the entity read ON when the line is detected. The old filters: - invert: syntax this page used previously is not valid - inversion belongs on the pin schema.
[env:esp32]
platform = espressif32
board = esp32dev
framework = arduino#include <Arduino.h>
#define SENSOR_PIN 16
void setup() {
pinMode(SENSOR_PIN, INPUT_PULLUP);
Serial.begin(115200);
Serial.println("KY-033 Line Tracking Sensor Test");
}
void loop() {
int sensor_value = digitalRead(SENSOR_PIN);
if (sensor_value == HIGH) {
Serial.println("Line detected");
} else {
Serial.println("No line detected");
}
delay(500);
}This PlatformIO code sets up GPIO16 as an input with a pull-up resistor for the KY-033 sensor. It prints "Line detected" or "No line detected" to the serial monitor based on the sensor's state.
import machine
import time
SENSOR_PIN = machine.Pin(16, machine.Pin.IN, machine.Pin.PULL_UP)
while True:
if SENSOR_PIN.value() == 1:
print("Line detected")
else:
print("No line detected")
time.sleep(0.5)This MicroPython script configures GPIO16 as an input with a pull-up resistor for the KY-033 sensor. It continuously checks for lines and prints the corresponding message every 500ms.
KY-033 specifications
About the KY-033
The KY-033 pairs a TCRT5000 reflective IR emitter/receiver pair with an LM393 comparator and a single potentiometer, the same comparator-plus-pot formula used across most of the KY-0xx analog modules. The TCRT5000 shines IR down at the surface below it and reads how much bounces back into its own phototransistor; the comparator turns that reflectivity reading into a clean digital edge once it crosses whatever level the pot is set to, rather than leaving a project to interpret a raw analog signal.
Because it works purely on contrast, it needs a genuinely dark line on a genuinely light background (or vice versa) and a fairly close, consistent mounting height above the surface - a few millimeters is typical - to keep the reflectivity reading stable. Like the KY-032’s reflective sensing, it’s not immune to strong ambient light washing out the signal, so it performs best indoors. A single KY-033 only reports one point of contrast; real line-following robots almost always run three or more of these (or an array board built around the same TCRT5000 sensor) side by side to track a line’s position, not just its presence.
KY-033 troubleshooting
No Line Detection
›
Issue: The sensor does not detect lines.
Solutions:
- Ensure proper wiring connections and verify the power supply voltage.
- Adjust the sensitivity using the onboard potentiometer to suit the surface and lighting conditions.
- Check for any obstructions or dirt on the sensor's infrared emitter and receiver.
False Positives
›
Issue: The sensor indicates a line when none is present.
Solutions:
- Reduce the sensitivity using the potentiometer to prevent detection of unintended surfaces.
- Ensure the sensor is not exposed to direct sunlight or strong ambient infrared sources.
- Verify that the sensor is mounted at an appropriate height and angle relative to the surface.
Where to buy the KY-033
Resources
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