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Project Notes

#483 WyLed!

.. when you allow an exploration of a chip (TM1638) to get a little out of hand! The WyLed free-form sculpture reacts to sound and blinks a 4-digit LED display. An ATTiny85 provides a little brain, and the TM1638 handles all input and output.


Here’s a quick demo..



I checked out the basic operation of the TM1638 in LEAP#481. This project tries to do something a little more interesting with the chip.

One thing led to another … and I ended up with a freeform sculpture that got a little out of hand!

Sound Detector

Sound input is detected with a circuit borrowed from LEAP#482 Electret Sound-level Trigger.

It provides a binary signal based on a preset threshold (adjustable with a pot). This is presented to the TM1638 as a “key” input via a 2N7000 mosfet.

LED Display

A 4-digit LED 7-segment display is used as a pair of “eyes”. For the display unit I have, the pin connections are as follows:

LED Module pin Function TM1638 pin
1 E SEG5/9
2 D SEG4/8
3 dp SEG8/12
4 C SEG3/7
5 G SEG7/11
6 D4 GRID1/24
7 B SEG2/6
8 D3 GRID2/23
9 D2 GRID3/22
10 F SEG6/10
11 A SEG1/5
12 D1 GRID4/21

Note: numbering the digits is pretty arbitrary - just need to follow a convention. In my case:

  • pins on the LED module are labelled D1-D4 from left to right
  • I have mapped these so that GRID1-GRID4 operate from right to left

Programming the ATtiny85

The WyLed.ino has some supporting classes TM1638.h and KeyController.h for interfacing with the TM1638, but does not require any additional libraries.

I used an ATtiny85 for the final build, and programmed it using the Arduino ISP.

See my notes on LEAP#070 for how this is done.




Breadboard Build

Especially for moderately complex freeform builds, validation of a breadboard is a smart first step! Note that I switched the SPI pin connections for the final ATtiny build (more convenient for construction).


Freeform Build

Came together in separately tested modules. First the electret input..


I’ve got some SMD TM1638 so I used a bit of perfboard to make wiring them up a little easier..


Bending the display module to shape..


Rabbit Ears? Why … beacause!


Adding a little more bling to the base..


Final build…


Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.