Published June 24, 2026 © GPL3+

Smart Lamp on W55MH32L-EVB

Build a smart lamp that automatically adjusts brightness based on ambient light levels

BeginnerFull instructions provided2 hours21

Things used in this project

Hardware components

WIZnet W55MH32L-EVB

DFRobot Analog Ambient Light Sensor For Arduino

RGB Light Module

Story

The W55MH32L-EVB is a high-performance evaluation board featuring the W55MH32L microcontroller, designed for industrial and IoT applications. At its heart is a 32-bit Arm® Cortex®-M3 core running at up to 216MHz, with 1024KB of flash memory, 96KB of SRAM, and a fully integrated hardware TCP/IP offload engine.

In this project, we'll build a smart lamp that:

Reads ambient light levels using an LDR (light-dependent resistor) via ADC
Drives an RGB LED with PWM to produce white light
Automatically brightens in the dark and dims in bright conditions
Uses white balance calibration for pure white output
Runs on MicroPython – no complex C code required

This is a perfect beginner-to-intermediate project for learning ADC, PWM, and analog-to-digital mapping on the W55MH32L-EVB.

Pin Connections

Component	    Pin	        W55MH32L-EVB Pin
LDR     	    Signal	PB0
LDR VCC	            3.3V	3.3V
LDR GND	            GND	        GND
RGB LED Red	    PWM	        PA6
RGB LED Green	    PWM	        PB9
RGB LED Blue	    PWM	        PA0
RGB LED +           3.3V	3.3V
RGB LED -	    GND	        GND

Code Explanation

1. Imports and Pin Definitions

from machine import Pin, ADC, PWM

We import:

Pin – GPIO control
ADC – analog-to-digital conversion for the LDR
PWM – pulse width modulation for the RGB LED

The W55MH32L-EVB has 3x 12-bit ADCs with up to 12 input channels, offering 1μs conversion time and a 0~3.6V input range.

2. Reading Light Levels (ADC)

ldr = ADC(Pin(LDR_PIN))
light_level = ldr.read_u16() >> 4   # convert to 12-bit (0-4095)

The ADC returns a 16-bit value (0-65535). We right‑shift by 4 to convert to the native 12-bit range (0-4095).

3. Brightness Mapping

brightness = map_value(light_level, 0, DARK_THRESHOLD, MAX_BRIGHTNESS, 0)

This maps the light reading to a brightness value:

Dark → low light_level → high brightness
Bright → high light_level → low brightness

4. White Light with PWM

The RGB LED produces white light by mixing red, green, and blue at equal intensities:

def set_white(brightness):
r = int(WHITE_BALANCE[0] * brightness / MAX_BRIGHTNESS)
g = int(WHITE_BALANCE[1] * brightness / MAX_BRIGHTNESS)
b = int(WHITE_BALANCE[2] * brightness / MAX_BRIGHTNESS)
RED_PIN.duty(r)
GREEN_PIN.duty(g)
BLUE_PIN.duty(b)

The duty() method takes a value from 0-255. WHITE_BALANCE lets you adjust the tint – for example, if white looks pink, reduce the red value.

Demo

Demo Video

Conclusion

This project demonstrates how easily you can build a smart, adaptive lamp on the W55MH32L-EVB using MicroPython. With just an LDR, an RGB LED, and a few lines of code, you've created an energy‑efficient lighting system that responds to its environment.

Next steps:

Add Ethernet connectivity for remote monitoring and control
Connect to Adafruit IO via MQTT to log light levels
Add a temperature sensor to adjust colour temperature (warm light at night)
Build a full smart home hub with multiple sensors

Build your own smart lamp today! 🚀

Code

# Lamp
from machine import Pin, ADC, PWM
import time, gc

# ===== Pin definitions =====
# Photosensor (analog input)
LDR_PIN = "PB0"
ldr = ADC(Pin(LDR_PIN))

# RGB LED (PWM pins)  produces white light
RED_PIN   = PWM(Pin("PA6", Pin.OUT))
GREEN_PIN = PWM(Pin("PB9", Pin.OUT))
BLUE_PIN  = PWM(Pin("PA0", Pin.OUT))

# Set PWM frequency
RED_PIN.freq(1000)
GREEN_PIN.freq(1000)
BLUE_PIN.freq(1000)

# ===== Configuration =====
# Adjust these values based on your environment
DARK_THRESHOLD = 200     # Below this, LED starts turning on (0-4095)
MAX_BRIGHTNESS = 255     # Maximum PWM duty (0-255)

# White color balance (adjust if white looks tinted)
# Higher values = more of that color
WHITE_BALANCE = (255, 255, 255)   # (R, G, B)  tweak to get pure white

# ===== Helper functions =====
def set_white(brightness):
    """
    Set white light with given brightness (0-255).
    Brightness is applied to all three channels with white balance.
    """
    r = int(WHITE_BALANCE[0] * brightness / MAX_BRIGHTNESS)
    g = int(WHITE_BALANCE[1] * brightness / MAX_BRIGHTNESS)
    b = int(WHITE_BALANCE[2] * brightness / MAX_BRIGHTNESS)
    
    RED_PIN.duty(r)
    GREEN_PIN.duty(g)
    BLUE_PIN.duty(b)

def map_value(value, in_min, in_max, out_min, out_max):
    """Map a value from one range to another."""
    return int((value - in_min) * (out_max - out_min) / (in_max - in_min) + out_min)

# ===== Main loop =====
print("Adaptive White Light Controller")
print(f"Dark threshold: {DARK_THRESHOLD}")
print("Darker  brighter | Lighter  dimmer")
print("Press Ctrl+C to stop\n")

while True:
    # Read light level (0-4095)
    light_level = ldr.read_u16() >> 4   # convert to 12-bit (0-4095)
    
    # Calculate brightness based on darkness
    if light_level >= DARK_THRESHOLD:
        # Bright enough  LED off
        brightness = 0
        status = "BRIGHT  OFF"
    else:
        # Too dark  calculate brightness
        # Darker = lower light_level = higher brightness
        brightness = map_value(light_level, 0, DARK_THRESHOLD, MAX_BRIGHTNESS, 0)
        brightness = max(0, min(MAX_BRIGHTNESS, brightness))
        status = f"DARK  brightness: {brightness:3d}%"
    
    # Apply brightness to white light
    set_white(brightness)
    
    # Show status (only when changed)
    print(f"Light: {light_level:4d} | {status}")
    time.sleep(0.3)
    gc.collect()