Sign up Calendar Latest Topics
 
 
 


Reply
  Author   Comment  
Angel of Rust

Registered:
Posts: 192
Reply with quote  #1 
Hi all,

This post is in response to a comment on a thread by Ogremasch (https://artemis.forumchitchat.com/post/update-dmx-basics-guide-9994591?pid=1307071430). Ogremasch noted that a lot of hardware with guides in the forum is hard to find commercially, if at all. My own experience with an off-the-shelf DMX-USB interface was less than stellar. Artemis needs an FTDI chip for the USB interface if using the DMX output that comes directly from the game. That also limits the choices. Some hardware sold with FTDI chips are using counterfeit chips, which don't always work.

Looking at what the USB interface does, and noting people's preference for an RJ45 jack, I have sketched up the following interface design. It needs some testing, but should be up to the task.

The protocols for the RJ45 side are taken from here:
https://en.wikipedia.org/wiki/DMX512#RJ-45_pinout

DMX-USB.png 
DMX-USB SCH.png 
DMX-USB cost.png 

The design is based on my experience building circuits to read the DMX output from Artemis. I also have the parts on-hand, so I am thinking about building one to see how it works.

ogremasch

Avatar / Picture

Registered:
Posts: 137
Reply with quote  #2 
I would be interested in testing it out if you make a spare one, let me know and I'll paypal you for the time and materials. 

If I am reading this correctly, this would be a single box that takes USB and Power and gives the user DMX out through RJ45 right? I am not great at reading schematics (yet).

Is there a distance limitation to using RJ45 ( I know that ethernet cables can ony be about 300 feet long for internet use and the max effective length of USB is about 16 feet, I am not sure if DMX has a similar limitation. the likely hood of having a 300 foot cable run is likely very small but I wanted to ask since I am new to the DMX stuff and you have experience with it. I have also heard of people in the Forums having trouble with their DMX that may be linked to the USB being too long. I have limited my DMX USB cable to 3 feet to avoid that problem which means I will need to apply the length to the DMX side of the board which leads me to needing to know if there is a max limit my server PC can be away from my bridge and still effectively control lights with relatively little or no perceivable lag. 

I look forward seeing more in this thread as the project develops. 

 
Angel of Rust

Registered:
Posts: 192
Reply with quote  #3 
Quote:
Originally Posted by ogremasch
I would be interested in testing it out if you make a spare one, let me know and I'll paypal you for the time and materials. 

If I am reading this correctly, this would be a single box that takes USB and Power and gives the user DMX out through RJ45 right? I am not great at reading schematics (yet).

 



I was originally just thinking about a replacement for the basic USB-to-DMX interface using an RJ45 jack for the DMX part. Having power on there seems like a good idea, so I added it:

USB DMX B.png   
DMX USB B SCH.png 

I put a 2.1 mm DC barrel jack on there so power can be provided at whatever voltage needed. Per Power-Over-Ethernet convention, I have assigned the RJ45 pins as follows:
1: D+ (data)
2: D- (data)
4 and 5: +Volt
7 and 8: ground

I plan to make one in the near future. I'll let you know how it goes.


Quote:
Originally Posted by ogremasch


Is there a distance limitation to using RJ45 ( I know that ethernet cables can ony be about 300 feet long for internet use and the max effective length of USB is about 16 feet, I am not sure if DMX has a similar limitation. the likely hood of having a 300 foot cable run is likely very small but I wanted to ask since I am new to the DMX stuff and you have experience with it. I have also heard of people in the Forums having trouble with their DMX that may be linked to the USB being too long. I have limited my DMX USB cable to 3 feet to avoid that problem which means I will need to apply the length to the DMX side of the board which leads me to needing to know if there is a max limit my server PC can be away from my bridge and still effectively control lights with relatively little or no perceivable lag. 

I look forward seeing more in this thread as the project develops. 

 


300 feet sounds about right. Because DMX uses RS485 protocol, which is a differential pair for signal, typically in twisted pair wire (such as cat 5 cable), it can go longer than any of us are likely to use up. As far as I can tell, it doesn't generate a lot of errors.

USB has a pretty short length limitation as you noted. Shorter is better. Otherwise, boosters are needed.



Angel of Rust

Registered:
Posts: 192
Reply with quote  #4 
PCB arrived today. Assembly was a breeze and the new interface works beautifully. I loaded up Artemis using the default DMX commands. The DMX controller and LED strip that Thom and Mark gave me at Armada III (DMX workshop - highly recommended!) worked perfectly.

Photo (homemade USB interface on the bottom; DMX controller from Armada III on top):
20190119_220519 - Copy.jpg 


e4mafia

Registered:
Posts: 86
Reply with quote  #5 
Quote:
Originally Posted by Angel of Rust




300 feet sounds about right. Because DMX uses RS485 protocol, which is a differential pair for signal, typically in twisted pair wire (such as cat 5 cable), it can go longer than any of us are likely to use up. As far as I can tell, it doesn't generate a lot of errors.

USB has a pretty short length limitation as you noted. Shorter is better. Otherwise, boosters are needed.




Great work as usual, Angel! - RS485 is tremendously useful - and that's why I use the SN75176 in my Arduino design. (TekNynja validated the SN75176 pair in his design, good out to 100 meters, so your 300 foot figure is good at a minimum) Lets me get that Arduino signal out over a good long distance. I got so frustrated at trying to figure it all out over USB  to my Arduino, though, so I just switched to ArtNet 😉 

This should be a great, easy to make project for a lot of people to get cranking with some DMX for low money, and not a Ton of learning needed. I think its a huge contribution to the community, so thank you!
e4mafia

Registered:
Posts: 86
Reply with quote  #6 
Going to have a party at the house on 2/9 - should have enough people and computers to run 2 bridges. Contemplating the risk/reward percentage of asking my wife if its ok for me to build out a second lighting rig 😉
I will definitely take some extensive video this time. I swear!!!!
Angel of Rust

Registered:
Posts: 192
Reply with quote  #7 
Thanks for the positive feedback!

I now have three USB-to-DMX interfaces that are built and tested with Artemis. I am very happy with the performance of these custom-built interfaces.

Doing some searching online, it looks like all the commercially-available DMX decoders (i.e., the box you need to plug the LEDs into), have the power supply attached with something other than the RJ45 jack (i.e., ethernet cable). Therefore, having the power jack on this board only benefits people who can make their own decoder boards, which entirely defeats the purpose of me making them. Therefore, the power jack is out of the final design.

In the interests of helping my fellow hobbyists, I have decided to follow through on a suggestion received here and sell these interfaces. I am looking at using Etsy as the selling platform, since they are setup for homemade stuff like this and I don't want to run a store.  https://www.etsy.com/listing/676845339/usb-to-dmx-interface-for-artemis?ref=shop_home_active_1

Important information for would-be Artemis DMX builders:

Stuff you need to use this interface:
  1. Artemis SBS server running on your PC
  2. FTDI drivers
  3. USB A to USB B cable
  4. ethernet cable
  5. DMX decoder with RJ45 jack (do a search for DMX512 decoder on your online seller of choice -- there are lots of options) - pin 1: D+, pin 2: D-, pins 7&8: ground
  6. LEDs, etc. (lots of people are using ribbons with the 12V variety)
  7. power supply that matches your LEDs
What is included with the USB-to-DMX interface I built:
  1. USB B jack
  2. RJ45 (ethernet jack - pin 1: D+, pin 2: D-, pins 7&8: ground)
  3. genuine FTDI chip
  4. tested to work with Artemis (i.e., the shield, red alert, etc. cues that ship with the game all work as they are supposed to)
I am currently looking at shipping to points in the US. I am including a no-frills pressboard base to help with mounting and setting up your own enclosure to protect the board (handling bare electronics can fry them).

Why would anyone want these when there are cheaper interfaces for sale?
  1. Ethernet jack is built in and wired to work with popular DMX decoders -- less wires for someone to figure out.
  2. I tested each of them with Artemis and they work.

photos:
20190120_210744 - Copy.jpg  20190120_153031 - Copy.jpg

Volpe42

Registered:
Posts: 5
Reply with quote  #8 
Would you sell just the parts without assembly? And if so how much would it be?
Angel of Rust

Registered:
Posts: 192
Reply with quote  #9 
Quote:
Originally Posted by Volpe42
Would you sell just the parts without assembly? And if so how much would it be?


Without assembly, the parts and shipping cost are $15.80. That assumes that the buyer is comfortable soldering all the parts on, including the SSOP28, which is not a beginner task. See photo below for the parts and a penny for scale. Because I will not be able to test everything prior to shipment, the buyer would need to assume all risk. I have no control over what happens during someone else's assembly. Therefore, I would advise against buying parts only. Send me a PM if you are still interested.

20190204_211919 - Copy.jpg 

One final note: I will only ship the parts for one board. If you want to make more than one board from parts, I recommend ordering them from the following vendor links:
symbol(s)partdetaillinkqty
C1capacitor10 uFhttps://www.digikey.com/product-detail/en/panasonic-electronic-components/ECE-A1EKS100/P975-ND/1605551
C2capacitor0.1 uFhttps://www.digikey.com/products/en?keywords=399-4266-ND1
D1green LED151031VS04000 https://www.digikey.com/product-detail/en/wurth-electronics-inc/151031VS04000/732-5007-ND/44899851
J1USB BED2983-ND https://www.digikey.com/product-detail/en/on-shore-technology-inc/USB-B1HSB6/ED2983-ND/26777441
J2RJ45 connector54602-908LFhttps://www.digikey.com/product-detail/en/amphenol-icc-fci/54602-908LF/609-1046-ND/10013601
R1-R2220 resistorRC1206JR-07220RLhttps://www.digikey.com/product-detail/en/yageo/RC1206JR-07220RL/311-220ERCT-ND/7321982
U1FT232RFT232RLhttps://www.digikey.com/product-detail/en/ftdi-future-technology-devices-international-ltd/FT232RL-TUBE/768-1306-ND/40069201
U2RS485SP3494EN-L https://www.digikey.com/product-detail/en/maxlinear-inc/SP3494EN-L/1016-1150-5-ND/24110821
 board https://oshpark.com/shared_projects/rzHQ8KRR1

Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.