This is a fix for my other tutorial : ” DIY USB DMX INTERFACE FOR UNDER $10“, apparently there are multiple versions of this board being sold. Depending on what site you bought it you may or may not have received a working chip. For those who are stuck with a non-working chip, this is a guide on how to modify yours to allow DMX data output. Solution found by GermAndy!
[su_spoiler title=”Requirements” style=”fancy”]
– non-working RS485 USB Board
– Soldering Iron, Tin
– Steady hand
[su_spoiler title=”The Problem” style=”fancy”]
There are different models of the USB RS485 interface being produced. Some of these models will not work out of the box and need some small modifications to work. I have not yet found a way to identify these boards but here is a fix thanks to GermAndy.
The problem seems to be with the 75176 chip:
The problem is with the DE pin… because the DMX data is a bit different from the original RS485 protocol. the DE pin does not raise because the RS485 protocol is not properly ended. This means there is no data send out as long as the protocol has not ended it’s stream correctly.
[su_spoiler title=”Solution 1″ style=”fancy”]
Lifting the DE / RE pin from the board. Lifting the DE/RE pins from the board will allow the 75176 chip to put out DMX data without waiting for a verification of the protocol. In most cases this solution should work. If for some reasons this did not work try solution 2.
Some boards still don’t work after lifting the DE/RE pins, Solution 2 fixes these boards:
[su_spoiler title=”Solution 2″ style=”fancy”]
If solution 1 did not work, you have to connect the DE/RE pin to the +5V of the 75176 chip. Since the chip is very small it’s recommended to use a soldering iron with a small tip. the +5v is the VCC pin on the chip diagram :
Image by Germandy
[su_spoiler title=”Fix For Mac(by David P.)” style=”fancy”]
So basically here are the steps for future readers:
On MacOS X (El Capitan)
* install D2xx Driver http://www.ftdichip.com/Drivers/D2XX.htm (read carefully the README file which is included – lot of manual steps in a terminal)
* install D2xxHelper http://www.ftdichip.com/Drivers/D2XX/MacOSX/D2xxHelper_v2.0.0.pkg
* Install and start QLC+
Everything should be fine. If not, also follow instructions on http://stevenbreuls.com/2014/03/fix-ftdi-dmx-interface-arduino-on-osx-10-9-mavericks/