ATTINY85 dmx RGB controller?

Projects General Guidance
1

I am attempting to make my own RGB+W led light controlled via DMX.
I can make it all happen on an uno, but could i make it work on an ATTINY85 ?
I would like to use the code found here, but stip it down to only four outputs R G B and W.

I also see that someone else has down a 4 ch PWM out on an 85 here:

http://www.technoblogy.com/show?LE0

thoughts?

2

OR if the 85 wouldn't work perhaps some other, smaller, arduino compatible chip from atmel?

3

The problem here will be the tiny85 lacks a hardware USART port so serial is normally done using SoftwareSerial and that is not going to work at 250000 baud.

4

There are ATtiny chips with a hardware USART, many of them are supported by third-party Arduino cores.

DMX uses differential signals, so you'll need a MAX485. You need to electrically isolate it from the ATtiny's power lines if the ATtiny will be grounded or connected to other devices, like a computer at the same time. This is to prevent ground loops.
If you use a normal 5V power adapter, that is isolated from the mains, that shouldn't be an issue, but if your LED driver is grounded or connected to earth, for example, you'll run into problems if you don't isolate the ATtiny from the LED driver using opto-couplers.

Pieter

5

Yup, very familiar with the MAX 485 and utilizing isolation, as i had to do so with my USB to DMX interface.

I also found this:

this looks like it could be a plug n play solution for what i want to do, but man i don't need an atmega, do I ?

There must be a smaller alternative.

6

Depends on how many LED's your driving as to what driver circuit is suitable.

This module seems to do everything in the one package but is a bit light on details like isolation and channel selection etc.

Another option is to use a RGB amplifier like these so all you need is a Arduino DMX receiver (with isolation) to drive it all.

7

If you don't need a small chip then an Atmega 328 is probably the simplest to use.

If you do need a small chip then the Attiny1634 is worth considering. It is nearly as powerful as an Atmega 328 but comes in an SOIC package which can be soldered by hand - unlike the small versions of the Atmega 328

...R