Summary of Physical computing with ATtiny
This article describes a DIY project where the author brings a Chilean "carranca" wall mask to life using an ATtiny microcontroller and a PIR motion sensor. The mask's eye holes house PWM-controlled neon LEDs for fading effects, while the mouth contains the sensor. The system utilizes interrupts and power-saving modes, powered by a repurposed Nokia battery, achieving four months of operation on a single charge.
Parts used in theChilean Wall Mask Motion Project:
- Chilean carranca wall mask
- ATtiny microcontroller
- PIR motion sensor
- Six neon LEDs (three per eye)
- Small 3.7V 860mAh battery from an old Nokia mobile phone
Story
I have a nice “carranca” (or wall mask) from Chile that stands in my corridor. It’s a very beautiful decorative mask that I liked from the very first moment I saw it at the shop. Few weeks ago I wondered if I could bring it to life by adding a motion sensor and some lights in it, since it has three convenient holes (two for the eyes and one for the mouth) and enough space on the back for housing wires, batteries and stuff.
Chilean wall mask bought in Pichilemu
The circuit that I had in mind for my ATtiny has very simple: a digital signal from a PIR motion sensor would come in one pin, another pin would send a digital signal out for the lights. At the end, the only change I made was to use two different pins for the eye-lights: a PWM one for the left eye, another PWM one for the right eye. (PWM so I could fade LEDs in and out, and independently from each other).
Chilean wall mask bought in Pichilemu
The circuit that I had in mind for my ATtiny has very simple: a digital signal from a PIR motion sensor would come in one pin, another pin would send a digital signal out for the lights. At the end, the only change I made was to use two different pins for the eye-lights: a PWM one for the left eye, another PWM one for the right eye. (PWM so I could fade LEDs in and out, and independently from each other).
Another thing that I had clear is that I was going to use interruptions and power-save-mode for saving me the trouble of switching/replacing battery every day.
Nowadays I’m using a small 3.7V 860mAh battery taken from an old Nokia mobile phone and it can provide enough energy to keep the system working for at least 4 months straight.
For more detail: Physical computing with ATtiny
- How can I bring a static wall mask to life?
Add a motion sensor and lights to the mask using an ATtiny microcontroller. - What is the best way to control the eye lights independently?
Use two different PWM pins on the ATtiny, one for each eye. - Does the project use interruptions and power-save modes?
Yes, these features are used to save the trouble of switching or replacing the battery daily. - Can I use a battery from an old mobile phone?
Yes, a small 3.7V 860mAh battery from an old Nokia phone works effectively. - How long does the battery last with this setup?
The system can provide enough energy to keep working for at least 4 months straight. - Where should I install the PIR motion sensor?
The sensor was installed in the mouth hole of the mask. - What type of LEDs were used for the eyes?
Three neon LEDs were placed in each eye hole. - Why were PWM signals chosen for the LEDs?
PWM allows the LEDs to fade in and out independently from each other.
