The concept for my final project is a lightbox that interacts with movement. The 2d led matrix on the top of the box will light up in correspondence to a person’s hand movement underneath the box. Using LDR’s to sense the level of light, when a hand is moved over the sensor the light level will reduce and this will then make the LED’s light up. The LED’s are 3mm, and sorted in clusters of the same colour. There is an assortment of 5 different colours randomly organised amongst 12 different clusters. Initially I wanted more LED’s so that the hand would be more visible as a shape, but I decided against it as I wasn’t sure how I could use the Arduino for so many inputs and outputs. I also thought about using led strips but they’re quite pricey and I like the effect of simple LEDs. The idea for this project is based on an interest into interaction between humans and lights and relates to my final year project.
Prototype
To prototype this project and to see if it would actually work in practice, I decided to do a mini box in cardboard, with 3 LDRs and 3 clusters of LED’s, I decided to solder this to brush up on my skills. The prototype works well and it helped me to realise that I prefer the box to be stood up, rather than being on stilts allowing a hand to go underneath, I also realised this might make it quite difficult to sense the light change. Having the box stood up with the LEDs on one side and the LDRs on the other, allows a person to simply move their hand behind the box and still works effectively to achieve what I originally wanted.
Technical Details
I am using an Arduino Nano for the project as it has more analog input and digital pins, which I require. My original plan was to link 2 separate Nano’s, with one as the input and one as the output, the Nano has 12 pins and there are 12 different LEDs.
The code takes in readings from 12 different LDR’s that are in corresponding places to the 12 clusters of LED’s. The readings are the levels of light that the LDR has sensed, I’ve set the level of light for the LED’s to then come on to be quite sensitive but also not too dark, meaning that it will respond when the LDR is not completely covered – a person could just hover their hand without having to touch the box. The code is mostly quite simplistic, it starts with the creation of an LED array, filled with the corresponding pins, and an LDR array, with the corresponding analog input pins. Then in the set up there’s a for loop, iterating from up to 8, on each iteration the pin mode for the LED pin is set to OUTPUT and the LDR pin is set to INPUT. In the void loop there is a series of if statements, if a certain LDR is below a certain amount, set the corresponding LED to HIGH, lighting it up, else set it to low.
Unfortunately, because there was such a vast amount of soldering there’s been a couple of problems with the LED’s, the majority of clusters work perfectly, with one or two not having all 5 LED’s working and a further few not working entirely. Additionally one of the lights has become quite ‘sticky’ and seems to stay on throughout, I think this is also to do with my soldering. I also struggled to understand how to connect 2 Arduino’s using I2C, whilst the video’s I followed were helpful, when it came to actually running the two Arduino’s together I couldn’t get it to work nor could I understand how the code would work with a master and slave. So for presentation purposes in the video I’ve connected all of the LED’s that do work, and the corresponding LDR’s for those.
The back of the LDR breadboard
Both soldered breadboards and arduino nano
References/Inspiration
- https://sandervandevelde.wordpress.com/2015/10/13/using-i2c-to-connect-two-arduino-nanos/
- https://www.youtube.com/watch?v=Jndb2vpAWwU
- http://www.techbitar.com/how-to-network-many-arduinos-with-sensors-using-i2c.html
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