Thursday, September 6, 2018

KatLight - the wonderlamp


For a very special woman, I needed a very special and unique present. Something really cool. How about a NeoPixel lamp, that can be controlled with a smartphone.
And why not adding some really funky features? Like turning the lamp on/off by the wave of your hand. And some nice animations. How about transmitting the temperature and humidity to your phone. And why not adding a scheduled sunrise, like the one from the sunrise simulator project? Too much? We'll see!

The Build

First of all I need a housing. I decided to use two old CD spindle boxes with different heights. The bigger one will house the Neopixels, the smaller one all the electronics. To make a little glow effect, I wanted to make the transparent plastic look like frosted glass. You can achieve it, by 'polishing' it on the inside with sandpaper. To mount the Nepixels I used a pump spray bottle, that I've cut into length. A lot of hot glue, some holes for the wires and it's a piece of cake.





Problem 1: APDS 9960

As soon as the APDS 9960 gesture sensor starts working it blocks the processing of the microcontroller as it tries to check for a gesture. This leads to the stage that the animations stopped working smoothly.
So I outsourced the gesture readings to an Arduino Nano. It communicates with the NodeMcu via three digital pins. I made my own small 'protocol'. By setting the pins to HIGH/LOW I can transmit eight different sensor states.

Problem 2: BME 280

The temperature sensor doesn't want to initialize with the begin()-function of the library.
I uploaded a I2C-scanner and checked for the I2C address. I searched the library of the sensor and find a method where you can define the address. With the call of begin(0x76, &Wire) the BME sensor just worked fine.


Does it look a little complicated? Maybe. But it's quite easy. Everything needs power, corresponding to it's specifications. The sensors can be powered by the voltage pins of the microcontrollers. The Neopixels need more current, as the controllers can provide, so it needs to be powered directly by the power supply. The APDS-9960 sensor is connected via I2C to the Nano. So it has to be pin A4 (SDA) and A5 (SCL). On the NodeMcu it doesn't matter which two pins we use, since nearly every two pins can be configured to act as I2C.


The lamp communicates via the MQTT protocol. I've put in a small Raspberry Pi Zero W, that acts as a MQTT broker. The Arduino Nano handles the gesture sensor and sends a signal to the NodeMcu to turn on/off all Neopixels. The NodeMcu has access to the BME280 sensor and publishes the temperature and the humidity to the MQTT broker. You can switch modes between On/Off and several animations. For nearly all functions (except the sunrise alarm and the disco light) you can set the desired RGB color.
The NodeMcu syncs time with a NTP server. So you can set a time when to start the sunrise-mode.


Off (0)

Well, every NeoPixel is turned off. The Lamp still reacts to the gesture sensor

On (1)

Sets all NeoPixels to the desired color.

Animation (2)

Sets the color of the stripe one pixel at a time, starting from the bottom, rising to the top.

Blue Light (3)

A rotating light. Like the one the firefighter or the police use it. But in any color you want.

Fire Simulation (4)

Random flicker, that starts at the bottom, rises and falls randomly.

Sparkle (5)

Turns on all LEDs at the desired color. Adds randomly some white sparkles to the light.

Blink (6)

Remember the classical blink-sketch? Now with a hole lamp and the color you like.

Sunrise Alarm (7)

You set the hour and minute where the alarm starts and it simulates a sunrise (like in the sunrise simulator project).

Disco Lights (8)

Randomly sets up to 4 LEDs to a random color.


Why using three boards, when one can do the trick?
Raspberry Pi Zero W - Well this is not really part of this project. But I wanted a MQTT broker for the ESP. And for upcoming projects. So why not put it in the lamp? Where I have the place and already the needed power line?

ESP 8266 - The heart of this project. Why not an ESP32? Cos' I don't have one

Arduino Nano - I had a small delay with the library controlling the APDS 9960 gesture sensor. I could have used a ESP32, but I don't have one. I could programmed it on the Pi, but I didn't want to. It increases the cost by about 3.50 € and I found a simple way to transmit simple data. So, who cares?!
Everything fits in the CD case on the lower section. And the more boards you can see there, the cooler it looks. And I like the way it looks.

Parts list

Neopixels 60/m
APDS 9960 Gesture sensor
BME 280
Arduino Nano
Raspberry Pi Zero W

Source Code

KatLight at bitbucket

Monday, July 9, 2018

Sunrise Simulator


For an event, I needed something special. How about a simulated sunrise. And it would be nice, if I could be able to remote control it and put it anywhere in the room. And of course it should be low cost. So the magic words for this are: NodeMCU, Neopixels, LiPo battery and a MQTT broker.


Nothing fancy here. The battery is connected to GND and the 3.3 Volts on the NodeMcu and also on GND and the 5 Volt input of the Neopixel stripe. Yes, we power a 5V Neopixel stripe with a 3.7V battery. When fully charged, it will work for some time. The Neopixel stripe mustn't be too long. I used just five pixels, and it works fine.





To simulate the sunrise, I'm setting one color at a time. So I divided the given time in three equal parts (one for each color). Within the first third of the time span, I raise the color value of the red LED from 0 to 255. Then I start with the green color. Blue at last. When all three colors are at max, you'll get a white glowing LED stripe.


I want to add a sunset algorithm and a full cycle of a sunrise, sunshine and a sunset. Just check the Git repository from time to time.


Git repository


Neopixels 60 LEDs/m
Electrical box
LiPo battery

Saturday, June 2, 2018

Talk, little buddy, talk!


In the beginning of 2018, I've discovered a Kickstarter project, called "The Little Buddy Talker". It's a small chip on a breakout board with 254 short voice messages and a 3.5mm audio jack.


The Little Buddy Talker is connected via SPI to the Arduino. And since TLBT is mounted on a breakoutboard with pins on the bottom, you can easily put it on a breadboard for wiring.

The Sound Chip

The chip on the board is the aP23682. It's a voice IC with the capability of recording up to 682sec voice in a 16bit quality. With this chip, you could probably make your own buddy talker. All you need are the voice samples.


What could have been better?

Since the buddy talker is connected via SPI, it would be usefull, if it had the standard SPI connector matching to the one on the Arduino Uno, Mega or Nano.
The buddy talker doesn't give any feedback, that indicates when a sound file has finished.


Kickstarter Project: "The Little Buddy Talker"

Arduino Uno
Jumper Wire
Audio cable 

Tuesday, March 20, 2018

Ultrasonic Reactive Light Bar


Well, I needed an eye catcher for the Maker Faire Ruhr 2018. Moving lights always gain the interest of people. Which includes me as well. The idea behind it: a LED stripe that changes color in response how close you get to it. The distance can be easily determined by a ultrasonic sensor. And with a Neopixel stripe I could easily change the color. But wait! With the Neopixels I can control each pixel individually. So instead of using one ultrasonic sensor, I'm using five. Each of the sensors triggers a different piece of the LED stripe.


If you want to measure the time the sound takes to  travel towards an object and back, you would usually use the puleIn-function. The problem is, that while the micro controller measures the time it does nothing else. So you would have to wait for the signal to return, before you can trigger another ultrasonic sensor. But we want to be able to operate several sensors simultaneously. I was about to imagine a proper algorithm, when I found out, that I wasn't the first to encounter this problem. And I'm not the first to find a solution for it. The library handles this issue.

The Build

I've found a wooden plank from a slatted frame with a length of 135cm. Perfect! I'm using one meter in the middle for placing the Neopixel stripe and five ultrasonic sensors.
The diameter of the ultrasonic sender and receiver tubes are close to 16mm. This is a drill size I had to purchase. I predrilled the holes with a 3mm drill, before using the 16mm one.
First I tried to glue the Neopixel stripe on to it, but that wouldn't hold. I fixed them with zip-ties.
I used an Arduino Nano as the controller, soldered a custom PCB and glued it on the back side of the lath.
I wanted the build to be robust. So I soldered wires from every sensor to the PCB. So that nothing will accidentally disconnect though the transport.

The Algorithm

The original design was that all LEDs were lit white when the maximum distance of three meters is detected. Technical speaking the values of all three colors are set to 254. The value of green and blue is now determined though the distance of an object to the sensors. Well it looked quite unspectacular, but it worked.



The power from the Arduino will not be enough to power all sensors and the LED stripe. So you need to add an external power line (5V).


Arduino Nano @ amazon
HC-SR04 Ultrasonic sensor @ amazon
Neopixels @ amazon
NewPing Libriary
Ultrasonic Lght Bar Code

Thursday, December 14, 2017

Digital Chalkboard


While I'm making videos for you, it is often necessary to write something important down. Sometimes just, so remember the identifier of the item. Or do you really think I can remember things like "ADXL345" or "VL53L0X"? And honestly: I haven't got much paper in my flat. So I thought about getting a some kind chalkboard. Less waste than writing on paper.

The e-Writing Board

I came across this little gadget. It's like a tablet where you can write on it with a stylus or your finger. I must have this thing! I asked Banggood, if they can provide me with one of those boards and they agreed.
That e-writing board is such a lightweight, I'm afraid to break it. And have you ever had a Etch-A-Sketch in your childhood? You could "write" and draw on a board without any batteries.

Different sizes

This board seems to be available from 4.5" up to 12" from different manufactures. And they are awesomely cheap! Haven't found one that exceeded the 25 € mark.




- Cheap
- Lightweight
- Low power consumption (Battery used only for erasing)
- Lock screen switch prevents accidental deleting


- Uses non-rechargeable batteries
- Lock screen switch doesn't prevent overwriting


EPOLLO Ultra Thin LCD Writing Tablet

Wholesale Computer Accessories

Friday, November 10, 2017

IoT - power it up!


Many devices uses current on standby mode. So we like to plug them into a power stripes with a switch on it. And we hide it behind some furniture because it's quite ugly to look at some cables. But now it's hard to reach. So.. if we could control the switch remotely within the comport of our couch? That's what IoT is made for.




Working with 110V AC or 230V AC is very dangerous and should be done only by a professional! Not only can it kill you, you also suffer incredible pain while you die!

Configure MQTT-Client

The MQTT broker and your client device has to be either in the same network or at least reachable through the internet (not really recommended).
You enter the IP and port of your broker to connect to it.
Add a new widget for on/off mode.
Then you subscribe to the channel the ESP is sending it's status to. It is: "esp/3/power/out" in this code.
You need now to enter the channel, where you want to publish commands to. The ESP subscribes messages from this channel. I used "esp/3/power/in" for this case.
Now, the only thing left to do is to define the messages for on and off. Usually it would be best to use 1 for on and 0 for off. I go for 10 for off and 11 for on.


ESP 8266 NodeMcu @ Amazon
Relay @ Amazon
Simple Power strip @ Amazon
Finding a Smartphone @ Amazon


Code for the ESP 8266

 Banggood 11.11 Global Shopping Carnival Electronic Special --

Thursday, October 12, 2017

Controlling the fan speed with your Arduino


You savaged a fan from an old PC to use it as a ventilator? Just hook it up to 12V and the sucker runs. Well, it runs at a constant speed. Maybe too fast, maybe too noisy. There must be a possibility to slow it down.

The idea

When you apply 12 Volts to it and then remove the power supply, it keeps spinning while getting slower. So if you continuously apply and remove the power, you can control the fan of the speed by the duration of the phases when the 12V is on and when it is not.

What do we need

The Arduino doesn't supply 12 Volts. So we have to use some sort of switch. An electronic switch. A MOSFET. That's a kind of transistor, that can handle the needed current/voltage needed. I used the IRF530N, because it was the only Mosfet I had and it matches the specification of the vent by far ;-). It's a N-channel Mosfet. That means you can control the connectivity of the negative pole of the power source to the fan by applying a positive voltage.


Pulse Width Modulation is the magic phrase. A digital output pin can only have two possible states. On or off. 1 or 0. HIGH or LOW. While HIGH is typically indicated by an output of 5 Volts (3.3 Volts occasionally) is LOW represented by a 0 Volt output. So how do we simulate an output of 2.5 Volts? Well, simply spoken, if we have a time frame of 10 seconds. Half the time we put out 5 Volts and half the time 0 Volts, we will have an output of 2.5 Volts of the time of those 10 seconds. Wired? Sure. But this is how math works ;-)



IRF530N at Amazon