Smart LED strips using a Blynk Interface

I recently decided that regular LED bulbs are too low-tech and non-computerized for my liking, so I decided to try designing a system that I could control remotely, for free, using smart WS2812 smart leds instead.

The Circuit

I interfaced a small strip of 26 smart LEDs to an ESP8266 NodeMCU board via a 1K resistor, and powered the whole thing from a USB connection. Probably not a good idea at full power, so I made sure not to run the strip at full power. 

The Code

The code for this circuit would be the most complex part, and I started by trying to get the ESP to control some smart LEDs. I did this by downloading adafruit's libraries and modifying their example code to do something really simple--wash some colors across the strip. This part of the code was pretty easy, although figuring out where the digital pin in the IDE linked to the physical pin was a little tricky. I found out that you could prepend a 'D' in front of the number to get the actual pin that was listed on the perf board.

#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
 #include <avr/power.h>
#endif


#define PIN D7


// Parameter 1 = number of pixels in strip
// Parameter 2 = Arduino pin number (most are valid)
// Parameter 3 = pixel type flags, add together as needed:
// NEO_KHZ800 800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
// NEO_KHZ400 400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)
// NEO_GRB Pixels are wired for GRB bitstream (most NeoPixel products)
// NEO_RGB Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
Adafruit_NeoPixel strip = Adafruit_NeoPixel(26, PIN, NEO_GRB + NEO_KHZ800);


// IMPORTANT: To reduce NeoPixel burnout risk, add 1000 uF capacitor across
// pixel power leads, add 300 - 500 Ohm resistor on first pixel's data input
// and minimize distance between Arduino and first pixel. Avoid connecting
// on a live circuit...if you must, connect GND first.


void setup() {
 // This is for Trinket 5V 16MHz, you can remove these three lines if you are not using a Trinket
 /*#if defined (__AVR_ATtiny85__)
 if (F_CPU == 16000000) clock_prescale_set(clock_div_1);
 #endif*/
 // End of trinket special code
 Serial.begin(115200);
 strip.begin();
 strip.show(); // Initialize all pixels to 'off'
}


// Fill the dots one after the other with a color
void colorWipe(uint32_t c, uint8_t wait) {
 for(uint16_t i=0; i<strip.numPixels(); i++) {
 strip.setPixelColor(i, c);
 strip.show();
 delay(wait);
 }
}


uint32_t Wheel(byte WheelPos) {
 WheelPos = 255 - WheelPos;
 if(WheelPos < 85) {
 return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
 }
 if(WheelPos < 170) {
 WheelPos -= 85;
 return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
 }
 WheelPos -= 170;
 return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}


void rainbow(uint8_t wait) {
 uint16_t i, j;


for(j=0; j<256; j++) {
 for(i=0; i<strip.numPixels(); i++) {
 strip.setPixelColor(i, Wheel((i+j) & 255));
 }
 strip.show();
 delay(wait);
 }
}


// Slightly different, this makes the rainbow equally distributed throughout
void rainbowCycle(uint8_t wait) {
 uint16_t i, j;


for(j=0; j<256*5; j++) { // 5 cycles of all colors on wheel
 for(i=0; i< strip.numPixels(); i++) {
 strip.setPixelColor(i, Wheel(((i * 256 / strip.numPixels()) + j) & 255));
 }
 strip.show();
 delay(wait);
 }
}


//Theatre-style crawling lights.
void theaterChase(uint32_t c, uint8_t wait) {
 for (int j=0; j<10; j++) { //do 10 cycles of chasing
 for (int q=0; q < 3; q++) {
 for (int i=0; i < strip.numPixels(); i=i+3) {
 strip.setPixelColor(i+q, c); //turn every third pixel on
 }
 strip.show();


delay(wait);


for (int i=0; i < strip.numPixels(); i=i+3) {
 strip.setPixelColor(i+q, 0); //turn every third pixel off
 }
 }
 }
}


//Theatre-style crawling lights with rainbow effect
void theaterChaseRainbow(uint8_t wait) {
 for (int j=0; j < 256; j++) { // cycle all 256 colors in the wheel
 for (int q=0; q < 3; q++) {
 for (int i=0; i < strip.numPixels(); i=i+3) {
 strip.setPixelColor(i+q, Wheel( (i+j) % 255)); //turn every third pixel on
 }
 strip.show();


delay(wait);


for (int i=0; i < strip.numPixels(); i=i+3) {
 strip.setPixelColor(i+q, 0); //turn every third pixel off
 }
 }
 }
}


// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.


void loop() {
 // Some example procedures showing how to display to the pixels:
 colorWipe(strip.Color(255, 0, 0), 10); // Red
 colorWipe(strip.Color(0, 255, 0), 10); // Green
 colorWipe(strip.Color(0, 0, 255), 10); // Blue
}

Where the Magic Happens

Once I had the led strip working with the ESP chip, I needed to get the blynk app on my phone working with the code. This was also fairly easy, though it took a bit of looking through the example code. I found out that using "virtual pins" was the trick. 

#define BLYNK_PRINT Serial // Comment this out to disable prints and save space
#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>


#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
 #include <avr/power.h>
#endif


#define PIN D7


char auth[] = "API key";


// Parameter 1 = number of pixels in strip
// Parameter 2 = Arduino pin number (most are valid)
// Parameter 3 = pixel type flags, add together as needed:
// NEO_KHZ800 800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
// NEO_KHZ400 400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)
// NEO_GRB Pixels are wired for GRB bitstream (most NeoPixel products)
// NEO_RGB Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
Adafruit_NeoPixel strip = Adafruit_NeoPixel(26, PIN, NEO_GRB + NEO_KHZ800);


// IMPORTANT: To reduce NeoPixel burnout risk, add 1000 uF capacitor across
// pixel power leads, add 300 - 500 Ohm resistor on first pixel's data input
// and minimize distance between Arduino and first pixel. Avoid connecting
// on a live circuit...if you must, connect GND first.


void setup() {
 // This is for Trinket 5V 16MHz, you can remove these three lines if you are not using a Trinket
 /*#if defined (__AVR_ATtiny85__)
 if (F_CPU == 16000000) clock_prescale_set(clock_div_1);
 #endif*/
 // End of trinket special code
 Serial.begin(115200);
 Blynk.begin(auth, "SSID", "password");
 strip.begin();
 strip.show(); // Initialize all pixels to 'off'
}


// Fill the dots one after the other with a color
void colorWipe(uint32_t c, uint8_t wait) {
 for(uint16_t i=0; i<strip.numPixels(); i++) {
 strip.setPixelColor(i, c);
 strip.show();
 delay(wait);
 }
}


uint32_t Wheel(byte WheelPos) {
 WheelPos = 255 - WheelPos;
 if(WheelPos < 85) {
 return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
 }
 if(WheelPos < 170) {
 WheelPos -= 85;
 return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
 }
 WheelPos -= 170;
 return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}


void rainbow(uint8_t wait) {
 uint16_t i, j;


for(j=0; j<256; j++) {
 for(i=0; i<strip.numPixels(); i++) {
 strip.setPixelColor(i, Wheel((i+j) & 255));
 }
 strip.show();
 delay(wait);
 }
}


// Slightly different, this makes the rainbow equally distributed throughout
void rainbowCycle(uint8_t wait) {
 uint16_t i, j;


for(j=0; j<256*5; j++) { // 5 cycles of all colors on wheel
 for(i=0; i< strip.numPixels(); i++) {
 strip.setPixelColor(i, Wheel(((i * 256 / strip.numPixels()) + j) & 255));
 }
 strip.show();
 delay(wait);
 }
}


//Theatre-style crawling lights.
void theaterChase(uint32_t c, uint8_t wait) {
 for (int j=0; j<10; j++) { //do 10 cycles of chasing
 for (int q=0; q < 3; q++) {
 for (int i=0; i < strip.numPixels(); i=i+3) {
 strip.setPixelColor(i+q, c); //turn every third pixel on
 }
 strip.show();


delay(wait);


for (int i=0; i < strip.numPixels(); i=i+3) {
 strip.setPixelColor(i+q, 0); //turn every third pixel off
 }
 }
 }
}


//Theatre-style crawling lights with rainbow effect
void theaterChaseRainbow(uint8_t wait) {
 for (int j=0; j < 256; j++) { // cycle all 256 colors in the wheel
 for (int q=0; q < 3; q++) {
 for (int i=0; i < strip.numPixels(); i=i+3) {
 strip.setPixelColor(i+q, Wheel( (i+j) % 255)); //turn every third pixel on
 }
 strip.show();


delay(wait);


for (int i=0; i < strip.numPixels(); i=i+3) {
 strip.setPixelColor(i+q, 0); //turn every third pixel off
 }
 }
 }
}


// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.


int rv = 0;
int gv = 0;
int bv = 0;


int red = 0;
int green = 0;
int blue = 0;


int on = 0;
double brightness = 1;


BLYNK_WRITE(1)
{
 if (param.asInt())
 {
 //HIGH
 on = 1;
 }
 else
 {
 //LOW
 on = 0;
 }
}


BLYNK_WRITE(2)
{
 rv = param.asInt();
 red = rv*brightness;
}


BLYNK_WRITE(3)
{
 gv = param.asInt();
 green = gv*brightness;
}


BLYNK_WRITE(4)
{
 bv = param.asInt();
 blue = bv*brightness;
}


BLYNK_WRITE(5)
{
 brightness = (param.asInt()+0.0)/255.0;
 red = brightness*rv;
 green = brightness*gv;
 blue = brightness*bv;
}


void loop() {
 // Some example procedures showing how to display to the pixels:
 //colorWipe(strip.Color(255, 0, 0), 10); // Red
 //colorWipe(strip.Color(0, 255, 0), 10); // Green
 //colorWipe(strip.Color(0, 0, 255), 10); // Blue
 Blynk.run();
 if(on == 1)
 colorWipe(strip.Color(red, green, blue), 10); // Red
 else
 colorWipe(strip.Color(0,0,0), 10); // Red
 delay(100);
}
This ended up being the final version of the code I ran on the prototype device. From there, it was a fairly simple matter of creating some sliders, buttons, and power switch on the blynk app and running everything.

The App

The power button interfaced to V1, the "red" slider to V2, the "green" slider to V3, the "blue" slider to V4, and the "intensity" (vertical) slider to V5. All of the sliders created a value from 0 to 255, and the button was either 0 or 1. 
When the button was pressed, the sliders could be moved around to adjust the intensity of the strip or change its color, and the strip would update in real time. It worked really well, and from anywhere in the world (with reception) too! 

Moving forward

As soon as I can get the funds, I'm going to try to scale the system up and interface it to a 5-meter, 150 led strip, with a high power 5V power supply. I'll post my results as soon as I do!

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