#004 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.

Build

Here’s a quick demo..

Notes

I checked out the basic operation of the TM1638 in LEAP#480. 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#481 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.

Construction

Breadboard

Schematic

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).

WyLed_bb_build