RGB LED Ring Small

Details

This is an accessory for the rotary encoder. There are 24 RGB LED disposed in a circle, the diameter of the circle is 30mm.

There is also a 9mm hole in the center where it’s possible to insert the rotary encoder. All the LEDs can be controlled individually with the i2c bus, the resolution is 24bit for each RGB led.

The controller is the IS31FL3746A, it has several features like:

Individual 256 PWM control steps
Individual 256 DC current steps
Global 256 step current setting
29kHz PWM frequency
Individual open and short error detect function
1MHz I2C-compatible interface
Supply voltage range: 2.7V to 5.5V

It’s possible to connect up to 15 RGB LED rings on the same bus.
For setting the address please check the note 6 of the datasheet!

What makes it special?

There are several alternatives made with the WS2812, but the LEDs are big with a low density. The RGB LED Ring density is higher because it uses a 2x2mm RGB LED.

With 24 LEDs, it has the same number of click of the most common rotary encoders. In this way, it’s possible to make some effects without losing in resolution.
The LEDs used are the NH-Z1921RGBA-SG used for outdoor display.

There are 8 SMD Jumpers where it’s possible to set 16 different I2C address. It also has another SMD jumper where it’s possible to enable the pull-up resistor on the I2C bus.

Pinout

There are two MOLEX-532610571 connectors with the following pinout

Name	Description	Voltage level
VCC	LED supply voltage	2.7V – 5.5V
GND	Ground	0V
VIO	Logic supply voltage	2.7 – 5.5V
SDA	I2C data	Same as VIO
SCL	I2C clock	Same as VIO

VCC and VIO can be different, for example VCC=5V and VIO=3.3V. With VCC=5V and all the LEDs on the current consumption is around 450mA, make sure that you power supply can give that much current!