Raspberry Pi with hardware RS485

[szadan]

Hello everyone!

I've been researching a lot lately but sadly i couldn't find any information about what i'm gonna ask. :/

So my plan is to build a lighting console. My question is about the brain of the whole thing the Raspberry Pi itself. It would run QLC and also would be in charge off directly controlling the DMX line. I'm thinking about an Arduino shield like solution which would wire the RS485 line transciever (in my case propably an SN75176) directly into the Raspberry Pi using it's I/O pins.

I know that the Raspberry can interact with the DMX lines using one of those USB/DMX controllers but that's not what i have in mind. The Raspberry Pi itself has an SPI and a UART interface at the I/O pins and i saw the demonstration video where the LED matrix was attached to the Pi itself using the SPI interface. My question is: Is it possible to have a direct DMX output on the UART pins or any other I/O pins? (which would then directly drive the line transciever)

So if anyone knows about it please help me.

Of course i will happily support the developers once i know that the software is capable of what i need

Btw.: I love this program! I had dozens of shows with it and it still amazes me!

[mcallegari]

Hi, have a look at this:
viewtopic.php?f=17&t=8894

[szadan]

Hi, have a look at this:
viewtopic.php?f=17&t=8894

Thanks for the fast info! It looks like i just wasn't using the right keyword for my research (damnit.) If anyone's interested i can write an Instructable page on the build of the console itself and my other project which is an ARM processor based 8 universe Artnet node and then share it with you guys.

The node is already built and tested (with QLC+ of course) and it's dirt cheap to make one yourself! (the whole thing was around 100$ with a 19" rack case)

[Mihai Andrei]

home made built UART converter :
chip used: SN75176B http://www.ti.com.cn/cn/lit/ds/symlink/sn75176b.pdf
only output... TX UART Raspberry...





It works perfectly

so for now I'm going to test this .. and universe 1
Universe 2 use an Arduino that converts me from ArtNet to DMX ...

[iamchrislaurie]

Mihai, that looks very interesting and exactly what I have bee looking for. Do you have a schematic that gives not all the relevant connections but also the details of the values of all the components?

[Mihai Andrei]

It's that easy do even with a single component that is the driver / converter from 232 to 485 .....
the components to be precise on my card are 9 of which one is the most important and the RS485 or other similar driver model then there are 3 Resistors , 10 ohm that protect 2 on the output which can supply light of the integrated overload, the third and on the ground between GND and raspberry dmx facility and here restricts small discharges, the other 2 are fulfilling a non-polarized capacitor (white) that filters the power supply and the black (470uF) on 5V which stabilizes, and in the end the LED it shows me the state in the signal. It is a bi-color LED with inverted diode (has only 2 pins) when there is no signal the pull-up voltage keeps red, just no signal turns yellow because a positive voltage is negative, then ok .. put signal with two 100 ohm resistor ... The connection is simple. GND GND raspberry
5V RS485 to 5V GPIO raspberry
RS485 to UART TX raspberry
Pins 2-3 on both the RS485 5V direct .. To enable the driver ..
Just like that .. of course QLC you choose the uart as output
--------------------------------
The one I now hold as proof ..
In future I will do something much better with the necessary components that serve ...
But now all right ...
On a Ardunio 2560 I have the same thing that converts me from ArtNet to DMX

later disign the schema and load

[Mihai Andrei]

here is also the schematics