Two-colour LED, 3 mm

By Admin, 15/09/2026 · 3 min read

Two-colour LED, 3 mm guide for the 37-in-1 Arduino Sensors Kit.

37-in-1 kit, module 27

KY-029: Two-colour LED, 3 mm

Red and green in a small 3 mm LED, one pin each. Plug it in, upload the sketch, then change the thing it senses and watch the reading.

All 37 modules Nano and shield wiring Joy-IT page for this module

KY-029, Two-colour LED, 3 mm

Red and green in a small 3 mm LED, one pin each.

How it works

Two-colour LED, 3 mm

What is going on

The 3 mm version of KY-011. Same wiring, same sketch, smaller and dimmer, which suits a panel indicator where the 5 mm one would glare.

Connections

Wiring to the Arduino Nano on its expansion shield

The pins below match the sketch further down this page; change one and change the other.

Power off first

Unplug the USB cable before you plug in, move or remove any module.

A lead plugged in live can touch the wrong pin for a moment, and 5 V on a signal pin is how a module dies. Unplug, wire, check the letters, then plug the cable back in.

Module pinGoes to

Module RedS row of the column marked 11, digital bank

Module GreenS row of the column marked 10, digital bank

Module -G row, ground

Where it plugs in on the shield

The ringed column is the one this module uses. G on top for ground, V in the middle for 5 V, S at the bottom for the signal. A module with more than one signal wire uses one column per wire.

Read the letters on the shield

Both banks on this shield read G, V, S from the top. The letters are printed at the ends of the rows.

The module's minus or GND pin goes to G, its plus or VCC pin to V, and each signal to the S row of the numbered column.

A module in backwards puts 5 V on the signal pin. Some survive it, plenty do not.

Starter sketch

Code you can copy and upload

Every sketch on these pages is compiled for the Arduino Nano before it is published. The pin numbers at the top match the connection table above.

ky029.inoArduino C++

1const uint8_t RED = 11, GREEN = 10;
2
3void setup() {
4  pinMode(RED, OUTPUT);
5  pinMode(GREEN, OUTPUT);
6}
7
8void loop() {
9  digitalWrite(RED, HIGH);
10  digitalWrite(GREEN, LOW);
11  delay(500);
12  digitalWrite(RED, LOW);
13  digitalWrite(GREEN, HIGH);
14  delay(500);
15}

Try first

Swap the two delays for 100 and it looks amber from across the room.

The quickest way to see it respond.

1

Unplug the USB cable. Plug the module into the column shown above, minus to G, plus to V, signal to S.

2

Plug the USB cable back in. Copy the sketch, upload it, and open Tools > Serial Monitor at 9600 baud.

3

Do the thing the module senses and watch the reading, the L LED, or the sound respond.

Reference

More on this module

The Joy-IT page has the datasheet figures and examples for other boards; the repository has the original vendor files.

Joy-IT SensorKit: KY-029
KY-numbered kit repository: datasheets and original examples
Arduino Nano and I/O expansion shield wiring
Arduino Nano and DHT11 electronics workshop
All 37 modules

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Two-colour LED, 3 mm

KY-029: Two-colour LED, 3 mm

KY-029, Two-colour LED, 3 mm

Two-colour LED, 3 mm

What is going on

Wiring to the Arduino Nano on its expansion shield

Where it plugs in on the shield

Read the letters on the shield

Code you can copy and upload

Swap the two delays for 100 and it looks amber from across the room.

More on this module

Help improve MakerAccess

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