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Arduino DMX receiver design - improvements

bytebitten

I am trying to design an Arduino based DMX receiver for use in a show where we have some custom builds.

In this case; we want to control a LED strip over DMX.

The design has 2 options for control: over DMX or WiFi. The toggle switches between DMX, WiFi or none.

The WiFi will be for debugging/testing of when using at home.

 

For what I found as seen in the image, I have some questions / doubts about some elements:

  • Are the resistors correct? Especially the 68, 22 and 120 Ohms.(one 120 ohm at the end)
  • Will this wiring work for the MAX485?
  • Is it needed to disconnect Rx/Tx prior to flashing new programming on the Arduino?
  • Is the ESP-01 done correct? (improved again in v3)
  • Will the dip-switch work this way? (Arduino sets pinmode input_pullup)
  • Is the 470 Ohm resistor advised for controlling the LED strip? (Seems advised for pin protection with power-on current)

 

Old design v.1:

image

Design v.4:

image

Notes:

  • The Arduino is the 5v version
  • The 470 Ohm resistor goes to the LED strip
  • The LED strip has its own power
  • The toggle2P3T slide switch has the states [Rx+Tx > ESP], [Rx > MAX485, Tx > none], [Rx+Tx > none]
  • The build will be done in phases (LEDs>red>green>blue>yellow) to keep it all working

 

If someone has remarks, improvements or questions; keep 'm coming image

I am still not very experienced in this stuff, but you learn best by doing image

 

Message was edited with v2, v3 and v4 in bold.

v1 replaced for search engines.

  • 0

    Hi Ruben,

     

    Are all the components in the module? Including both connectors? If so,I would not place the 120ohm resistor in that way, I would connect the connectors 1-1, 2-2, 3-3, the 120 resitor conected pin2-resistor-pin3, and it would be posible to disconect it, then I would place the 22ohm resistor, conector pin2-resistor-B, connector pin3-resistor-A.

     

    About the ESP-01, I think it works at 3v3, so for the Rx it should be place a voltage divider, its seems it is not well wired in the schematic.

     

    Also I would use different pins instead a toggle, so different UARTs in the Arduino, one for the 485, and another for the ESP, then with a toggle connected to digital input, you can switch to decide which UART to use (by software).

     

    Hope to be usefull, regards

  • 0

    I would have thought that the dip switch would require individual pull down resistors for each leg of the switch. It may be the drawing has been simplified and it should have read 10K x 8 array.

  • 0 in reply to gihu

    For the DMX; I will check what resistors are excessive. From your answer I get some are.

     

    For the ESP-01; the Rx/Tx from 5v>3.3v needs a divider; that is where the 1K and 2K are for.

    But 3.3v>5v is compatible as they both have the same thresholds (where 2.4+v registers as up/1, if I'm correct).

     

    The UART pins would work, but from what I read these needs to be disconnected if reprogramming the Arduino. I want to do that without taking it all appart.

  • 0 in reply to WarrenW

    As to what I can find, resistors per pin;

    - is used with LEDs

    - is used with 5v for single pin read

     

    Even https://arduino.cc/en/Tutorial/InputPullupSerial shows a schematic without resistors at all.

  • 0 in reply to bytebitten

    The issue with this is that lets assume the internals of the arduino has a resistance to pull up the SINGLE pins. When you connect a SINGLE resistor to MULTIPLE pins how will that interact with the other pins?

    I cannot confirm that this is the case as my arduinos are at home at the moment.

    Based on past experience with multi dip switched inputs it is always a good practice to individually apply resistors so not interaction can occur.

    Cheers

    Warren.

  • 0 in reply to bytebitten

    Alternatively since you are pulling down inputs - omit the pull down resistor and go straight to ground with the common line of the dip switch array.

  • 0 in reply to bytebitten

    The 1k and 2k resistors are connected in series and you should use a N-type transistor to control the LED strip.

    Maybe you will need a pullup resistor on the ESP reset pin but I'm not sure.

  • 0

    Will this light up our lives?

     

    Approach this project slowly to understand each portion - Don't wire everything up in one foul swoop and expect it to work instantly.

    Try working on LED bar first

    Then the ESP-01 connection (But not WIFI connection just yet.)

    And finally the DMX portion.

     

    To get the LED bar working you'll have to ask yourself these questions.

    How much power does the LED bar draw?

    What are its voltage requirements?

    How do you control it.

     

    From that you progress and get it working.

     

    Have a look at some of my Element 14 blogs for my approach to getting things to work.

     

  • 0 in reply to bytebitten

    Hi Ruben,

     

    1k and 2k resistor are not well connected to act as a voltage divider. 1K resistor shuold connect (in your drawing) toggle and ESP(Rx pin), and 2K resistor should connect ESP (Rx pin) to GND.

     

    Hope that helps,

  • 0 in reply to bytebitten

    Also you can avoid the 10K resistor in between dip-switch and GND, and connect it directly, then the inputs shuold be configures as digital input with internal pull-up