Overview

This implements a Wifi Artnet receiver to receive Artnet frames and send them out over DMX. The Idea is to fit the modules into DMX equipment and be able to use Wifi instead of DMX cabling.

The module uses WifiManager to connect to a Wifi network on initial startup. On subsequent boots, it will reconnect to the same network again with, no configuration necessary. The initial hostname is based on the hardware ID of the ESP8266. This name can be changed and saved.

The Artnet/DMX Universe can be configured, along with the max frame size and the update rate.

A WS2812 RGB LED is used to show the display status. The same status can be seen on the console output or the webinterface.

The colors displayed are as follows:

Color	Meaning
Red	The device is booting
Yellow	Connecting to Wifi
Green (blink slow)	Device is ready and connected to Wifi
Cyan	Artnet frames are detected, but ignored as the universe does not match
Green	Artnet frames are received and transmitted to DMX
Green (blink fast)	DMX frames are transmitted from buffer after Artnet signal loss

Wherever there is activity on the web interface (configuration, monitoring), the LED turns blue. During web interface activity, the DMX512 output is silenced. A smooth web interface and smooth DMX signalling don't go together.

Special features

The MAX485 transmitter is switched off, when no frames are sent. This places the driver in high-Z mode and allows to use the DMX input with the ESP-DMX device still connected. The aim is to solder the device directly to the DMX fixture, but retaining the option to use conventional DMX.
Fan control of the internal fan dependent on the measured temperature
Programmable hold time to hold the last setting if the Artnet signal goes away. For example if I use a tablet as remote control it may go to sleep, stopping to transmit Artnet frames. This feature keeps the lights on.

Limitations

My cheap PARs seem not to like frames shorter than 512 channels.

Components / Hardware

Most ESP8266 modules or boards can be used. Personally I use the Wemos D1 with the protoboard shield. The circuit is built on the protoboard.

Wemos D1 mini
MAX485 module or chip
WS2812 RGB LED
NPN transistor (with enough current for your fan), optional
100k NTC for temperature measurement, optional

Wiring diagram

     Wemos D1:
                        +-----+ 
                   Rst  +  W  +  Tx
      NTC <-        A0  +  E  +  Rx
      Fan <- D0/GPIO16  +  M  +  D1/GPIO5   -> RS422 En
    LED_B <- D5/GPIO14  +  O  +  D2/GPIO4 
    LED_R <- D6/GPIO12  +  S  +  D3/GPIO0*
NEO/LED_G <- D7/GPIO13  +     +  D4/GPIO2*  -> RS422 Tx
             D8/GPIO15* +  D  +  Gnd
                   3V3  +  1  +  5V
                        +-----+ 

        MAX485: 1 Rx      vcc 8  -> Wemos D1 3V3 power
            2 RxEn   outb 7  -> DMX fixture
 Wemod D1 D1 <- 3 TxEn   outa 6  -> DMX fixture
 Wemod D1 D4 <- 4 Tx      gnd 5  -> Wemos D1 Gnd

There is are schematics and a wiring diagram among the files.

Some remarks:

There is a prototype board for the D1 on which the Max485 fits nicely
I don't use a 120 Ohm termination resistor as it is not necessary with the short cable length within the fixture itself and would require to be disconnected if the fixture cabled conventionally.

ToDo

See the todo list

Reference

The Sketch by Robert Oosterveld http://robertoostenveld.nl/art-net-to-dmx512-with-esp8266 has served as starting point.

markusb / esp-dmx

readme