Example 31: PS2 Joystick

Experiment Overview

A PS2 joystick module provides two-axis analog output (X/Y) and one button output (Z-axis press), suitable for game control, pan-tilt control, robotic arm manipulation, and similar scenarios.

Hardware Wiring

Board Label	GPIO Pin	Connected Device
VRx	GPIO34	X-axis analog output
VRy	GPIO35	Y-axis analog output
SW	GPIO4	Button (LOW when pressed)

X/Y axes output ~1.65V (ADC ~2048) at center; 0V or 3.3V at full deflection.

JSON Configuration Example

{
  "peripherals": [
    {
      "id": "joystick_x",
      "name": "Joystick X-Axis",
      "type": 15,
      "enabled": false,
      "pins": [34],
      "params": {}
    },
    {
      "id": "joystick_y",
      "name": "Joystick Y-Axis",
      "type": 15,
      "enabled": false,
      "pins": [35],
      "params": {}
    },
    {
      "id": "joystick_btn",
      "name": "Joystick Button",
      "type": 13,
      "enabled": false,
      "pins": [4],
      "params": {}
    }
  ]
}

Peripheral Execution Linkage

Scenario: Joystick Servo Control (Timer Trigger + Script)

Feature: Control servo angle (0-180°) via joystick X-axis

Web UI Configuration Steps

Step 1: Ensure Servo Peripheral is Configured

• Peripheral ID: servo_01
• Type: Servo

Step 2: Create Rule

1. Click Peripheral Execution in the left menu
2. Click New Rule button
3. Fill in basic configuration:
   • Rule Name: Joystick Servo Control
   • Report Data: ✅ Enabled
   • Enable: ✅ Enabled

Step 3: Configure Trigger

1. Click Add Trigger button

2. Fill in trigger configuration:

   Field	Value	Description
   Trigger Type	Select Timer Trigger	Periodic sampling
   Timer Mode	Select Fixed Interval	Millisecond interval
   Interval	100	100ms (fast response)

Step 4: Configure Action (Script Conversion)

1. Click Add Action button

2. Fill in:

   • Action Type: Select Command Script
   • Action Parameter:

   var x=analogRead('joystick_x');
   var angle=Math.round(x*180/4095);
   servoWrite('servo_01',angle);

3. Click Save button

PS2 Joystick Value Reference

Status	ADC Value	Description
Center	~2048	Middle position (dead zone ±100)
Left/Up Extreme	0	Minimum value
Right/Down Extreme	4095	Maximum value

Notes

1. Dead Zone: Joystick center ADC value is ~2000-2100 (not exactly 2048); set ±100 dead zone
2. Pin Selection: Must use ADC-capable pins (GPIO32-39)
3. Sampling Rate: 50-100ms sampling interval recommended for control applications
4. Calibration: Record center value on first use as offset compensation baseline