Example 42: IR Tracking Sensor

Experiment Overview

An IR tracking sensor identifies black lines (low reflection) and white backgrounds (high reflection) by detecting ground reflectance differences. Suitable for line-following robots, path tracking, and similar applications.

Hardware Wiring

Board Label	GPIO Pin	Connected Device
OUT_L	GPIO4	Left tracking module DO
OUT_R	GPIO15	Right tracking module DO

Outputs HIGH over black lines (no reflection); outputs LOW over white ground (reflection detected).

JSON Configuration Example

{
  "peripherals": [
    {
      "id": "track_left",
      "name": "Tracking - Left",
      "type": 11,
      "enabled": false,
      "pins": [4],
      "params": {}
    },
    {
      "id": "track_right",
      "name": "Tracking - Right",
      "type": 11,
      "enabled": false,
      "pins": [15],
      "params": {}
    }
  ]
}

Peripheral Execution Linkage

Scenario: Line-Following Control (Timer Trigger + Script)

Feature: Control motor direction based on left/right sensor states to follow a black line

Web UI Configuration Steps

Step 1: Ensure Motor Peripherals are Configured

• Motor IN1: motor_in1 (GPIO Output)
• Motor IN2: motor_in2 (GPIO Output)

Step 2: Create Rule

1. Click Peripheral Config in the left menu → Switch to Peripheral Execution tab
2. Click New Rule button
3. Fill in basic configuration:
   • Rule Name: Line-Following Control
   • Report Data: ✅ Enabled
   • Enable: ✅ Enabled

Step 3: Configure Trigger (Timer Trigger)

1. Click Add Trigger button

2. Fill in trigger configuration:

   Field	Value	Description
   Trigger Type	Select Timer Trigger	Periodic detection
   Timer Mode	Select Fixed Interval	Millisecond interval
   Interval	50	50ms (fast response)

Step 4: Configure Action (Script Control)

1. Click Add Action button

2. Fill in:

   • Action Type: Select Command Script
   • Action Parameter:

   var l=gpioRead('track_left');
   var r=gpioRead('track_right');
   if(l==1&&r==0){
     gpioWrite('motor_in1',0);
     gpioWrite('motor_in2',1);
   } else if(l==0&&r==1){
     gpioWrite('motor_in1',1);
     gpioWrite('motor_in2',0);
   } else {
     gpioWrite('motor_in1',1);
     gpioWrite('motor_in2',1);
   }

3. Click Save button

Line-Following Control Logic

Left Sensor	Right Sensor	Status	Action
1 (Black Line)	0 (White Ground)	Drift Left	Turn Right
0 (White Ground)	1 (Black Line)	Drift Right	Turn Left
1 (Black Line)	1 (Black Line)	Center	Go Straight
0 (White Ground)	0 (White Ground)	Off Line	Straight / Stop

Notes

1. Mounting Height: 1-2cm from ground for best results
2. Black Line Width: Recommended 2-3cm width, matching sensor spacing
3. Ambient Light: Strong light may affect detection; add a light shield
4. Multi-Sensor Expansion: Use 3-5 sensors for improved tracking accuracy