LedBorg - An ultra bright RGB LED add on board for your Raspberry Pi
Capabilities
The LedBorg provides a tri-colour LED controllable from the Raspberry Pis GPIO header.
Using simple on / off logic it can provide a total of seven colours as well as off.
Using software based pulse width modulation (PWM) it is capable of many more colours, around a million in fact.
There is also a Linux driver available here capable of producing 26 colours and off for more advanced users.
GPIO pins
The LedBorg uses the following GPIO pins:
| RPi pin | WiringPi pin | LedBorg use |
|---|---|---|
| GPIO 17 | 0 | |
| GPIO 27 (21 on rev1) | 2 |
|
| GPIO 22 | 3 | |
| 5v (power) | Power for the LEDs | |
| Ground | 0v reference |
The on board chip converts the 3.3V logic level signals used by the Raspberry Pi into the 5V levels used by the LEDs.
On the revision 1 Raspberry Pi GPIO 21 is used instead of GPIO 27 due to the header change, see here for more details.
A HIGH logic level (also known as 1 or ON) on one of the GPIO pins connected to an LED colour enables that colour channel of the LED.
A LOW logic level (also known as 0 or OFF) on one of the GPIO pins connected to an LED colour disables that colour channel of the LED.
The extended range of colours is produced by varying the channel between these high and low states quickly, which in turn dims the channel.
Electrical details
The board layout on LedBorg allows for the proper amount of heatsinking to keep the board cool from the heat generated by the LED.
A decoupling capacitor is connected to the 5V rail near the chip, this means live plugging/unplugging is not recommended as it may reset the Raspberry Pi when doing so.
The LED is an AVAGO ASMT-YTC2-0AA02 with the following specifications:
Red 450mcd/629nm, Green 560mcd/521nm, Blue 180mcd/464nm
120 degree viewing angle
The full schematic for LedBorg is available here.
Other details
The LedBorg is approximately L35.5mm x W16.5mm x H11.5mm in size and fits inside a lot of available Raspberry Pi cases.
