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Quick Start

This guide will help you get DimmerLink up and running in minutes.

What You'll Need

  1. DimmerLink — controller board
  2. Dimmer — TRIAC module with external control support
  3. Microcontroller or SBC — Arduino, ESP32, Raspberry Pi, etc.
  4. Jumper wires
  5. Lamp for testing (incandescent or dimmable LED)

Step 1: Choose an Interface

Feature UART I2C
Wiring TX/RX crossed SDA/SCL direct
Code complexity Command packets Register access
Recommendation For advanced users For beginners

💡 Tip: We recommend I2C for most projects — simpler code, easier debugging, and more robust than UART.

⚠️ Important — DimmerLink ships in UART mode. Out of the box the board listens on UART. To use I2C, first send the switch-to-I2C command over UART once (02 5B); the setting is stored, so you only do this one time. See I2C Communication for details.

🔌 I2C wiring: I2C requires 4.7 kΩ pull-up resistors on both SDA and SCL to the bus voltage (3.3 V). Without them the device will not be detected by an I2C scan.

ℹ️ You can test communication with no AC connected. DimmerLink powers from its logic VCC, so it responds to UART/I2C commands (including the frequency-request check) even before mains is wired. The on-board status LEDs, however, only light when AC is present.

Step 2: Wiring

Input (to your project):

Pin Function
VCC Power 3.3V
GND Ground
TX/SDA UART TX or I2C SDA
RX/SCL UART RX or I2C SCL

Output (to dimmer module):

Pin Function
VCC Power
GND Ground
Z-C Zero-Cross signal
Dim TRIAC control

Connection Diagram

plaintext
[Your Project] ←→ [DimmerLink] ←→ [Dimmer] ←→ [Mains + Lamp]

Detailed dimmer and load connection diagrams (lamps, heaters): Dimmers power and load connection

Step 3: Upload Code

Arduino:

cpp
#include <Wire.h>
#define DIMMER_ADDR 0x50
#define REG_LEVEL   0x10
void setup() {
    Wire.begin();
}
void loop() {
    // Smooth brightness change
    for (int level = 0; level <= 100; level += 10) {
        setLevel(level);
        delay(500);
    }
    for (int level = 100; level >= 0; level -= 10) {
        setLevel(level);
        delay(500);
    }
}
void setLevel(uint8_t level) {
    Wire.beginTransmission(DIMMER_ADDR);
    Wire.write(REG_LEVEL);
    Wire.write(level);
    Wire.endTransmission();
}

MicroPython (ESP32, Raspberry Pi Pico):

python
from machine import I2C, Pin
import time
# ESP32: scl=22, sda=21
# Raspberry Pi Pico: scl=5, sda=4
i2c = I2C(0, scl=Pin(22), sda=Pin(21), freq=100000)
DIMMER_ADDR = 0x50
REG_LEVEL = 0x10
def set_level(level):
    i2c.writeto_mem(DIMMER_ADDR, REG_LEVEL, bytes([level]))
# Smooth brightness change
while True:
    for level in range(0, 101, 10):
        set_level(level)
        time.sleep(0.5)

Python (Raspberry Pi):

python
from smbus2 import SMBus
import time
bus = SMBus(1)
DIMMER_ADDR = 0x50
REG_LEVEL = 0x10
def set_level(level):
    bus.write_byte_data(DIMMER_ADDR, REG_LEVEL, level)
# Set brightness to 50%
set_level(50)

Option B: UART

⚠️ UART is timing-sensitive. If you see random bytes, dropped replies, or disconnects: give the board time to answer (allow ~100–200 ms between sending a command and reading the reply), and read all returned bytes for each command — a leftover unread byte desynchronizes the next exchange. Fixed 115200 8N1, raw HEX packets. If UART stays unreliable, switch to I2C (see note in Step 1) — it is the more robust interface.

Arduino:

cpp
// Use Serial1 (or SoftwareSerial for Uno)
#define DIMMER_SERIAL Serial1
void setup() {
    DIMMER_SERIAL.begin(115200);
    checkConnection();
}
void loop() {
    setLevel(50);  // 50%
    delay(2000);
    setLevel(100); // 100%
    delay(2000);
}
void setLevel(uint8_t level) {
    uint8_t cmd[] = {0x02, 0x53, 0x00, level};
    DIMMER_SERIAL.write(cmd, 4);
    // Wait for response
    delay(10);
    if (DIMMER_SERIAL.available()) {
        uint8_t response = DIMMER_SERIAL.read();
        // 0x00 = OK
    }
}
// Connection check — request mains frequency
void checkConnection() {
    uint8_t cmd[] = {0x02, 0x52};
    Serial1.write(cmd, 2);
    delay(50);
    if (Serial1.available() >= 2) {
        uint8_t status = Serial1.read();
        uint8_t freq = Serial1.read();
        if (status == 0x00) {
            Serial.print("OK! Mains frequency: ");
            Serial.print(freq);
            Serial.println(" Hz");
        }
    }
}

Python:

python
import serial
import time
ser = serial.Serial('/dev/ttyUSB0', 115200, timeout=0.1)
def set_level(level):
    cmd = bytes([0x02, 0x53, 0x00, level])
    ser.write(cmd)
    response = ser.read(1)
    return len(response) > 0 and response[0] == 0x00
# Set brightness to 50%
if set_level(50):
    print("OK")
else:
    print("Error")

Step 4: Verify Operation

  1. Upload the code to your microcontroller
  2. Power up DimmerLink
  3. Observe — the lamp should change brightness

Connection Verification

I2C — Device Scan

Arduino:

cpp
#include <Wire.h>
void setup() {
    Serial.begin(115200);
    Wire.begin();
    Serial.println("Scanning for I2C devices...");
    Wire.beginTransmission(0x50);
    if (Wire.endTransmission() == 0) {
        Serial.println("DimmerLink found at 0x50");
    } else {
        Serial.println("Device not found!");
    }
}
void loop() {}

Raspberry Pi (command line):

bash
# Install if not present:
sudo apt install i2c-tools
# Scan for devices:
i2cdetect -y 1

Expected output — 50 at the intersection of row 5 and column 0.

UART — Response Check

Send the mains frequency request command:

plaintext
HEX: 02 52

Expected response: - 00 32 — OK, frequency 50 Hz - 00 3C — OK, frequency 60 Hz

Not Working?

Problem Solution
No response Check wiring and power
Error 0xFC EEPROM write error
I2C doesn't see device Check connections and pull-up resistors
Incorrect brightness Check logic levels (3.3V/5V)

What's Next?

← Overview | Contents | Next: Hardware Connection →

What You'll Need Step 1: Choose an Interface Step 2: Wiring Step 3: Upload Code Step 4: Verify Operation Connection Verification Not Working? What's Next?