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ESP32

This is the Guide to explain how to use and control the ESP32 for controlling Motors or LEDs.

MQTT is a subscription based broker-client system that works with topics and messages. In our environment the broker is typically running on the RasPi. Typical clients are Microcontrollers like the ESP32, Smartphones and the RasPi itself. A good introduction on the topic can be found on Steves Guide.

Our tested ESP32 family

Our MQTT-command scheme

We decided to make the topics and messages (=payloads) human-readable. Wildcards are possible as well. Our typically setup-environment is displayed in the image above and hence let's assume we use:

  • 1x Raspi
  • 1x ESP32 to control the LED-array
  • 1x ESP32 to control the motors
  • 1x Smartphone

Our environment is planned such that there is 1 RasPi that supervises at least 1 setup and hosts the MQTT-broker.

(1) Topics

Hence, the topic structure is:

/<SETUP>/<DEVICE>/<GENERALCOMMAND>

We even standardized the lengths per Wordgroup, meaning:

  • SETUP is of length 4 with 1 alphabetical and 3 numerical letters, eg S001 for your first UC2 setup
  • DEVICE is of length 5 with 3 alphabetical and 2 numerical letters, eg LAR01 for the first Led-ARray in your setup
  • GENERALCOMMAND is a general interface to communicate with whatsoever device via only 3 cmd options "ANNO", "RECM" and "STAT"

So a typical topic could look like this:

/S007/LAR03/RECM

where the 3rd LED-Array in the 7th Setup listens to what you have to say. While the ESP32 typically subscribe as listeners to "RECM" they can post to "STAT" and "ANNO". For now, the latter two are deactivated.

(2) MESSAGES

The messages are typically a concatenation of ASCII alphanumerical characters that use a "+" sign as sequence seperators. Eg

PXL+20+127+255+50

is a typical message that could be send to the above topic and would set the 20th Pixel to the RGB value [127,255,50].

(3) Typical Commands: the LED-Array

For the LED device the typical commands are:

COMMAND RANGE EXAMPLE
NA UINT8 [0...4] "NA+4"
PXL UINT8 [0...64,0...255,0...255,0...255] = [pixelNBR,R,G,B] "PXL+20+127+255+50"
HLINE UINT8 [0...8,0...8,0...8,0...8,0...255,0...255,0...255] = [x,y,w,h,R,G,B] "HLINE+0+2+8+1+120+120+120" -> not active
VLINE UINT8 [0...8,0...8,0...8,0...8,0...255,0...255,0...255] = [x,y,w,h,R,G,B] "VLINE+0+2+8+1+10+10+90" -> not active
RECT UINT8 [0...8,0...8,0...8,0...8,0...255,0...255,0...255] = [x,y,w,h,R,G,B] "RECT+1+1+3+3+250+130+250"
CIRC UINT8 [0...255,0...255,0...255] = [R,G,B] "CIRC+85+86+87" -> not active
LEFT UINT8 [0...255,0...255,0...255] = [R,G,B] "LEFT+85+86+87"
RIGHT UINT8 [0...255,0...255,0...255] = [R,G,B] "RIGHT+85+86+87"
TOP UINT8 [0...255,0...255,0...255] = [R,G,B] "TOP+85+86+87"
BOTTOM UINT8 [0...255,0...255,0...255] = [R,G,B] "BOTTOM+85+86+87"
CLEAR None "CLEAR"
PRESET None "PRESET"
SETPRE None "SETPRE"
FLYBY None "FLYBY"
ALIVE None "ALIVE"

(4) Typical Commands: the x,y,z Motor and Fluo-Module

COMMAND FORMAT & RANGE EXAMPLE
DRVX INT -10000...10000 "DRVX+-1000"
DRVY INT -10000...10000 "DRVY+0"
DRVZ INT -10000...10000 "DRVZ+1000"
FLUO INT 0...255 "FLUO+42"

The conversation factor from the sent steps to finally executed steps by the StepperMotor is: 10. The "FLUO" command has no further factor. The given range is a suggestion and no hard limits are implemented (yet).

Of course you can do whatever you want, but that's the way we set it up. :)

Setting up the IDE

The ESP32 is a mircocontroller that has many functional units (chips/routines), a real second thread (core) as well as an enhanced RAM as compared to the ARDUINO. Hence, it is way more powerful. Still, there is no possibility to store data/variables generated on runtime for longer than the runtime. Hence, we flash the device initially and then keep the inserted parameters and code. Once environmental parameters (e.g. IP-adresses or Topic-names) change, we have to change the code and flash the device again. For flashing, you can choose between multiple IDEs. While we chose to work with VSCode and PlatformIO we belief that the ARDUINO IDE is a solid environment for starters.

  • Download and install the ARDUINO-IDE as described here
  • Prepare your IDE to work with the ESP32 boards, as awesomly described here
  • Let's assume your IDE is setup as default, hence your standard library PATH will be %HOME%\Documents\Arduino\libraries\ and your presets in the IDE should look like this:

Now, we need to add the libraries necessary to compile and flash our Scripts onto ESP32.

  • As described here go to Include Library -> Manage Libraries and install the following packages:
    • Adafruit_GFX
    • Adafruit_NeoMatrix
    • Adafruit_NeoPixel
  • Download the PubSubClient-Package from here, unzip, rename to pubsubclient and copy into your Arduino/library folder as before or explained here
  • The WSWire-Library can be found here

You can find a tested version (with our code) of the packages as well as our StepMotor-Library under ARDUINO/LIBRARIES except for PubSubClient, which can be found in the ESP32/LIBRARIES folder.

Getting MQTT properties

If you followed our guide how to setup a new RasPi with our GUI from scratch or if you already have a mosquitto (MQTT-protocol) server running on the Raspberry, we now need to know the IP-adress of the MQTT-server host (in this case = IP of RasPi). In a terminal (on the Raspi) enter:

$ ifconfig wlan0 | grep -w inet

In our case the IP is: 192.168.178.160. Now it depends which device you cant to connect. The available devices are:

Learn how to prepare the code, flash it onto the ESP32 and run the device here.

Credits

R. Heintzmann, X. Uwurukundo, H. Wang, B. Marsikova, B. Diederich, Lichtwerkstatt, IPHT Jena