Example 39: LCD1602 Display

Experiment Overview

LCD1602 is a 16-column × 2-row character LCD display. With an I2C adapter board (PCF8574), it can be connected using only 2 wires. FastBee includes a dedicated LCD1602 peripheral type (type: 52), supporting 16x2 and 20x4 character LCDs via PCF8574/PCF8574A I2C expander.

Enable the FASTBEE_ENABLE_LCD1602=1 compile option to use this feature.

Hardware Wiring

Board Label	GPIO Pin	Connected Device
SDA	GPIO21	I2C adapter SDA
SCL	GPIO22	I2C adapter SCL

I2C adapter address is typically 0x27 or 0x3F.

JSON Configuration Example

{
  "peripherals": [
    {
      "id": "lcd1602",
      "name": "LCD1602 Display",
      "type": 52,
      "enabled": false,
      "pins": [21, 22],
      "params": {
        "width": 16,
        "height": 2,
        "interface": 2
      }
    }
  ]
}

Peripheral Execution Linkage

⚠️ Note: LCD1602 character display driver is pending implementation; below is the expected configuration structure

Future Scenario: Display Sensor Data (Timer Trigger)

Feature: Periodically display temperature and system status on LCD1602

Expected Web UI Configuration Steps

Step 1: Ensure Sensor Peripheral is Configured

• DHT11: dht_01 (Temperature & Humidity Sensor)

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: LCD Status Display
   • Report Data: ❌ Disabled
   • Enable: ❌ Disabled (pending firmware support)

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 display
   Timer Mode	Select Fixed Interval	Second interval
   Interval	5	5 seconds

Step 4: Configure Action (Display Control)

1. Click Add Action button

2. Fill in:

   • Action Type: Select Display Control
   • Target Peripheral: Select lcd1602
   • Display Content:

   Line 1: FastBee IoT
   Line 2: T:${dht_01.temperature}C

3. Click Save button

LCD1602 Specifications

Feature	Description
Display Capacity	16 characters × 2 rows
I2C Address	0x27 or 0x3F
Character Set	ASCII only, no Chinese support
Refresh Rate	≥1 second recommended
Backlight Control	Supported via I2C adapter

Notes

1. I2C Address: Commonly 0x27 (PCF8574) or 0x3F (PCF8574A)
2. Backlight: Backlight on/off can be controlled via I2C
3. Contrast: Adapter board has a potentiometer for contrast adjustment
4. Character Limit: Only supports ASCII characters, no Chinese
5. Refresh Rate: LCD response is slow; 1 second+ interval recommended
6. Current Status: LCD1602 driver implemented (FASTBEE_ENABLE_LCD1602=1); for graphical OLED, refer to Example 23