What is it?

This is an accessory for the rotary encoder. There are 48 RGB LED disposed in a circle, the diameter of the circle is 40mm.

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 IS31FL3745, 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 16 RGB LED rings on the same bus.

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 48 LEDs, it has exactly double of the number 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

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!

Cable option

10 cm cable with both connector

Used for connecting multiple boards connectors

30 cm cable with one cable and free wires

Used for connecting one board to the controller

Documentation (in progress)

The documentations of the project is available on GitHub

There are the:

• Gerbers, BOM and pick and place
• 3D file of the board
• Schematic

Package

The package includes 1 RGB LED Ring assembled and tested.

The cable is required, please choose among the two types.

Difference with the previous version

• Different LED controller: IS31FL3745 instead of the IS31FL3737
• Better RGB LED: NH-Z1921RGBA-SG
• Added two connector for a better board to board connection
• Possibility to set 16 different I2C address instead of 4