After clearing out some junk, which included an old halogen desk lamp, I was thinking about putting in an LED light behind the PC monitor.
Then I remembered I’d bought a ring of 24 RGB LEDs from Aliexpress last year & hadn’t used it in a project.
I also had a spare Arduino Nano, and all the things I’d need to allow me to hook up a dial (potentiometer) for the light level, and button to cycle through different colour modes.
Here’s a quick video of it in action..
Parts
LED Ring – £2
Arduino Nano – £1.75
Breadboard & bits – £1.25
Wiring it up
It’s an easy one to wire up.. I took a few basic examples and mashed them together to get what I wanted from the design.
I’m not an electronics expert, and approached this like I approach software development; write it in manageable/testable chunks, which I can implement and test individually, then bolt it all together.
The code for the project is pretty simple.. I think the most complicated bit is handling the button, which needed debounce functionality.
| #include <Adafruit_NeoPixel.h> | |
| #ifdef __AVR__ | |
| #include <avr/power.h> | |
| #endif | |
| #define PIN 6 // pin on the Arduino is connected to the LED ring | |
| #define NUMPIXELS 24 // Number of pixels on the LED ring | |
| #define POT_PIN 0 // Potentiometer pin | |
| #define BUTTON_PIN 2 // Button pin | |
| Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800); | |
| int showType = 0; | |
| bool oldState = HIGH; | |
| void setup() { | |
| pinMode(BUTTON_PIN, INPUT_PULLUP); // Declare pushbutton as input | |
| pixels.begin(); // This initializes the NeoPixel library. | |
| } | |
| void loop() { | |
| // Read the potentiometer value and translate to how many pixels we want to illuminate | |
| int value = analogRead(POT_PIN); | |
| value = map(value, 0, 1023, 0, 25); | |
| // Switch colours if the button is pressed | |
| bool newState = digitalRead(BUTTON_PIN); | |
| if (newState == LOW && oldState == HIGH) { | |
| delay(20); // Short delay to debounce button. | |
| // Check if button is still low after debounce. | |
| newState = digitalRead(BUTTON_PIN); | |
| if (newState == LOW) { | |
| // Cycle through different colour schemes | |
| showType++; | |
| if (showType > 8) showType=0; | |
| } | |
| } | |
| oldState = newState; // Set the last button state to the old state. | |
| uint32_t color = pixels.Color(255,255,255); // default to white when first booted | |
| if (showType==1) color = pixels.Color(0,0,255); // blue | |
| if (showType==2) color = pixels.Color(0,255,0); // green | |
| if (showType==3) color = pixels.Color(255,0,0); // red | |
| if (showType==4) color = pixels.Color(0,127,255); | |
| if (showType==5) color = pixels.Color(255,127,0); | |
| if (showType==6) color = pixels.Color(255,0,127); | |
| if (showType==7) color = pixels.Color(0,255,255); | |
| if (showType==8) color = pixels.Color(127,127,255); | |
| // Illuminate X pixels depending on how far the potentiometer is turned | |
| for(int i=0;i<NUMPIXELS;i++){ | |
| if (i<value) { | |
| pixels.setPixelColor(i, color); | |
| } else { | |
| pixels.setPixelColor(i, pixels.Color(0,0,0)); // Don't show anything | |
| } | |
| } | |
| pixels.show(); // This sends the updated pixel configuration to the hardware. | |
| } |
And here are a few pictures of it in place behind the PC monitor..
