Review – Macetech Shiftbrite RGB LED module
Today we are going to examine the Macetech Shiftbrite modules. These are high-powered RGB LEDs that are mounted on a small PCB with a controller IC that you can control easily with an AVR or Arduino system, with a brightness of 8800 mcd per colour, and a viewing angle of 140 degrees. Ouch! In this review we will be using the Arduino system, however there is AVR instructions and a demonstration available here. First of all, here is one example:
You can order Shiftbrites with and without header pins. The IC on the bottom of the unit is an Allegro A6281 three-channel constant current LED driver with programmable pulse-width modulation control. For interest, here is the data sheet: Allegro 6281.pdf In other words, it takes care of which LED segment(s)to illuminate, their brightness, and for how long. It sounds like a lot but is easy to understand.
The name Shiftbrite is a bit of a giveaway to how it actually works. It is very bright – looking at it directly during operation is dangerous, and the shift relates to how the control data is used by the modules. To put it simply they are 32-bit shift registers with an RGB LED attached… so all you need to do is have 32 bits of data sent to them – in a similar method just like a 74HC595 shift register. The good thing about this is you can control more than one Shiftbrite using a daisy-chain method – with a catch. If you have, say, three in a row and you only want to change the second Shiftbrite, you need to send out data to refresh all three of them. But don’t panic, doing so is quite easy.
There are two concepts to understand to effectively use a Shiftbrite – pulse width modulation and how colours are represented digitally. PWM is quite easy with LEDs, it is a method of controlling the brightness by switching them on and off rapidly to give the illusion of brightness. For example, at full PWM, the LED is on… at 50 % the LED is on for 50% of the time, and off for 50% of the time. Below is a demonstration of PWM from another article:
Representing colours digitally is also easy. As you may know, colours can be created by mixing the primary colours red, green and blue. With the Shiftbrite each primary colour can have a value of between zero (off) and 1023 (full). Say for example, you only want red – so you set the data to be: red – 1023, green – zero, blue zero. And so on. For a very good explanation on how this works please visit this site. The Shiftbrite uses 10 bits of data for each colour, allowing a range of resulting colours in the billions. So let’s get blinking…
Here is an example sketch from the Macetech website: demo1.pdf. Connection to the board is very easy, just 5V and GND, and the four data lines:
The only concern when running Shiftbrites is their power consumption. One unit will use 20 mA per primary colour, which is fine for an Arduino or compatible board. However if you are using two or more, you will need to supply an external power supply to the Shiftbrites, between 5.5 and 9 volts, and 60 mA per module. Moving on, here is a video of one Shiftbrite in action, just rotating between red, green and blue:
That is bright. The only thing better than one Shiftbrite is two, so here you are. In the second demonstration, we are using the same sketch as in the first. So the second Shiftbrite is reacting to the data as shifted out by the first when it receives new data:
So now for some more colours. Using the following sketch demo 2.pdf the Shiftbrite generates shades of primary colours, then all the colours randomly. This time to save my eyesight it uses the ping-pong ball diffuser from the blinky project:
Well I hope you found this review interesting, and helped you think of something new to make. In conclusion I would consider the Shiftbrite great for use in projects where you need the blinking and display fun of RGB LEDs, but with a greater brightness. You can purchase Shiftbrites and a range of fun stuff from Little Bird Electronics.
As always, thank you for reading and I look forward to your comments and so on. Furthermore, don’t be shy in pointing out errors or places that could use improvement. Please subscribe using one of the methods at the top-right of this web page to receive updates on new posts. Or join our new Google Group.
[Note - The Shiftbrites were purchased by myself personally and reviewed without notifying the manufacturer or retailer]
Otherwise, have fun, be good to each other – and make something!