WiFi DCC Command Station for Model Railway

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Introduction: WiFi DCC Command Station for Model Railway

Update 17 July 2020 : Amended both sketches - use
DCC_WiFi_v2.ino
and
command_station_wifi_v4.ino
-------------------------------------------------------------

[Update 16 Feb 2020: Amended sketch for Arduino to meet Hornby decoder cv read requirements - please use 'command_station_wifi_v1_2.ino']

[Update 1st Oct 2019:
New version of App released to include full CV read/write routines 'LocoMotive WiFi DCC'
New sketch for DCC_WiFI (On ESP 32S) and Command Station (On Arduino Pro Mini)]


Further to my Instructable on a Bluetooth / Android App version of a DCC Command Station, I have developed the system to be controlled by WiFi.

This WiFi version can be run on more than one Android device giving the user multiple DCC throttles.
Up to 50 locos may be listed within the App menu.

The ESP32s (Node MCU) module creates the local WiFI router and communicates with the App to receive DCC packets. The packets are sent to an Arduino Pro Mini and output to a LMD18200T h-bridge.

Firstly, you must set up the Arduino IDE to run the code for the ESP32 node Node32S (or NodeMCU-32S) device. The following links gives full instructions for PC and Mac setups :

'Last minute Engineers' or Randon tutorials or GitHub link

The main components of the system are :

ESP32S (eBay link)
Arduino Pro Mini
LMD18200T h-bridge module

Power supply:For OO/HO layouts use a 14v DC power supply (e.g. laptop charger unit from eBay).
14V 4 Amp version with a 2.5 x 5.5 mm plug, search for eBay item # 401748337196

15V 2 Amp version with a 2.1 x 5.5 mm plug, search for eBay item # 401871382681

Do NOT use a DC train controller as these do not provide a true DC voltage.

All other components are available on eBay.

1 off LMD18200T H-bridge
1 off 0.1 ohm 2W Metal Film Resistor (11.5 mm x 4.5 mm)
3 off Capacitor 0.1uf
2 off 10kΩ Resistor
1 off Capacitor 10uf 25v;
1 off Capacitor 470uf 25v or 35v;
1 off 2 Way Screw PCB Terminal Block 13.5A 200V 3.5mm
1 off 4.7kΩ Resistor

For 5v power use either :
1 off L7805 CV Positive Voltage Regulator IC with 1 Heatsink TO 220 style for L7805
Or, Traco 5v 1 amp Switching regulator (RS Components Stock No. 666-4360)

2 off 15 pin Female Header Edge Pins Strip 0.1" 2.54mm
2 off 12 pin Female Header Edge Pins Strip 0.1" 2.54mm
1 off 6 pin 2.54mm PCB Universal Screw Terminal Block
1 off Zener Diode 4.7V 0.5 watt or 3.6v 0.5 watt

Step 1: Insight Into ESP32 Features & Using It With Arduino IDE

Few years back, ESP8266 took the embedded IoT world by storm. For less than $3, you could get a programmable, WiFi-enabled micro-controller being able to monitor and control things from anywhere in the world. Now Espressif (The semiconductor company behind the ESP8266) has released a perfect super-charged upgrade: the ESP32. Being successor to ESP8266; not only does it have a WiFi support, but it also features Bluetooth 4.0 (BLE/Bluetooth Smart) – perfect for just about any IoT project.

The ESP32 Integrates 802.11b/g/n HT40 Wi-Fi transceiver, so it can not only connect to a WiFi network and interact with the Internet, but it can also set up a network of its own, allowing other devices to connect directly to it. The ESP32 supports WiFi Direct as well, which is a good option for peer-to-peer connection without the need of an access point. The WiFi Direct is easier to setup and the data transfer speeds are much better than Bluetooth.
The chip also has dual mode Bluetooth capabilities, meaning it supports both Bluetooth 4.0 (BLE/Bluetooth Smart) and Bluetooth Classic (BT), making it even more versatile.

In this project, I only use the WiFi capability to create a local server for the DCC command station to communicate with an Android App.

In theory, it is possible to only use the ESP module, however the clock generation code required is completely different from the AVR clock code use in the Arduino Pro Mini. I leave this task to another reader out there!

The connections between ESP32 and Arduino are really simple - see circuit diagram. The RX,TX from Pro Mini connect to the Rx2,Tx2 of the ESP device. Note the use of resistors to step down the signal level to the ESP32 as it can only use 3.3v levels.

Step 2: Circuit Diagram and PCB

The Arduino circuit is the same as that used in the Bluetooth version. I have added sockets to mount the ESP32 in place of the BT module. This PCB is now available for sale on eBay here.
The Arduino must be a Pro Mini ATmega 328 16MHz 5v version

The ESP32 acts as a WiFi server, receiving data from the WiFi_DCC App and transmitting this to the Arduino via TX2 pin. Any data going back to the App will be sent via the RX2 pin.

A current sense resistor 0.1 ohm detects overload and short circuit conditions which then sets down the system until a reset signal is received.

The LMD18200T h-bridge converts the DCC packet into a AC waveform that supplies the track with power and data.

Note: The 5 volt regulator in a TO-220 package gets hot when powering the ESP32 module (up to 200 mA) therefore a heatsink must be used.

Step 3: ESP32 Node MCU Sketch

Updated 17/7/2020 - please use new sketch attached 'DCC_WiFi_v2.ino'

This sketch sets up your local server and receives updates from the App on your android device.
The communication is 2-way to allow data on current drawn by the system to be reported back to the App.

Go to GitHub link to obtain required library files here.

ESP32S must be programmed via the Arduino IDE.
Go to Tools, Board, and select Node32S or NodeMCU-32S from list.

Go to Tools, Port and select /dev/cu.SLAB_USBtoUART

That is the option on my Apple MacBook Air - something similar on PC I would imagine.

The Arduino sketch 'DCC_WiFi_v1.ino' requires these library files :

// for App 'LocoMotive WiFi Controller'

// creates a WiFi access point and provides a web server on it

#include "WiFi.h"
#include "WiFiClient.h"
#include "WiFiAP.h"

const char *ssid = "DCC_WiFi"; // must be matched in Android device settings
const char *password = "123456789"; // must be entered when above ssid is selected

WiFiServer server(80);

This sketch is free with purchase of my PCB on eBay

Step 4: Arduino Pro Mini Sketch

Updated 17/7/2020 - please use new sketch attached 'command_station_wifi_v1_4.ino'

This sketch is free with purchase of my PCB on eBay

Step 5: WiFi_DCC App

The App is called 'LocoMotive WiFi DCC' available on Google Play Store here.

The App may be loaded onto more than one Android device to provide multiple DCC throttles.

Note: App works well on Android 7, however on Android 9 upwards you must switch OFF 'mobile data' in the phone settings

You may also have to switch ON GPS in the Location settings of your device.

Also, you must click the Get WiFi button a couple of times to connect effectively.

1 Person Made This Project!

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18 Discussions

0
schuie52
schuie52

Question 10 months ago

Hi i am having all sorts of problems with the wi fi app trying to get my pc to reccognise the module as well as the arduino , i have downloaded so many programs the esp 23 core with no success i have almost lost the will to live,the arduino program eventually down loaded can some one please help forgot to mention that the actual board is not completed yet as i am waiting for the sockets to plug the boards in
michael

0
BillC35
BillC35

Answer 10 months ago

Hi Michael, sorry to hear of these problems. I understand you have loaded the ESP32S with the code successfully now. Can you connect to the ESP32S WiFi now , using correct name and password on your Android device settings ?
What device (phone or tablet type) are you using ?
What Android version does this device have ?
I have found Android 7 works fine, however Android 9 requires you to switch on GPS in the Location settings of your device.
Bill

0
schuie52
schuie52

Reply 10 months ago

Hi bill i think you misunderstood my problem i have not loaded the ESP32 code yet when i plug the board in to my laptop it shows a unknown device and is looking for a driver i have followed last minute engineers advice to no avail, what am i doing wrong, the command station Wi-fi has loaded ok on my android phone and my kindle fire which run on android 7 platform any help would be appreciated the build was quite straightforward the arduino pro managed to download the sketch which seems to be ok, i am still waiting for the sockets for the esp 32 so i have been trying to program as a stand alone unit.
regards
michael

0
BillC35
BillC35

Reply 10 months ago

Michael, the ESP32S must be programmed via the Arduino IDE.
Go to Tools, Board, and select NodeMCU-32S from list.
Go to Tools, Port and select
/dev/cu.SLAB_USBtoUART
That is the option on my Apple MacBook Air - something similar on PC I would imagine.
See how far you get with that and let me know outcome.

0
schuie52
schuie52

Reply 10 months ago

Hi bill had a go this morning and those files are not on my pc under the boards every thing is arduino so I don’t know where to go now this is very frustrating as I do not have a clue as what to do next .
regards
michael

0
BillC35
BillC35

Reply 10 months ago

Michael, I think that means the ESP32 Core has not been installed properly.
I am afraid you will have to go back to the Lastminuteengineers site and follow
'Installing the ESP32 Core on - Windows OS' (for a PC)
When successful, the Arduino boards list will contain a variety of options including
Node32S and NodeMCU-32S, etc

0
schuie52
schuie52

Reply 10 months ago

Hi bill still no joy i have followed the instructions from last minute engineers and this is what i have done, i opened my computer , documents and found to arduino files one just says arduino and the other arduino data, so i opened the arduino folder and inside was another folder called libraries within this folder i created another folder called Espressif and within the folder created another folder with all the files i opened the tools folder and opened a file called get this down loaded some files when i started arduino and went to tools, boards no esp 32 what is going wrong my arduino version is 1.8.10 what can i do next as this is driving me crazy spending at least 5 hours. A day trying to resolve i even watched you tube and still no joy
can you suggest what am i doing wrong
regards
michael

0
schuie52
schuie52

Reply 9 months ago

Hi bill sorry to bother you on Sunday i followed the link that you sent me and i done it and the esp 32 is all up and running i think i have installed the software it appears to have written to the board although there was no indication on the esp 32 , still tinkering about but at least i am a step closer to completing this project
regards
michael

0
BillC35
BillC35

Reply 9 months ago

No problem, Michael, I am glad to hear of progress. A sense of satisfaction for you at last.
Please let me know how you get on with next steps in project.

0
schuie52
schuie52

Reply 9 months ago

Will do bill if all goes well and it is up and running will post pic’s of the unit
regards
michael

0
schuie52
schuie52

Reply 10 months ago

Hi bill will have a go but i an still waiting for the 15p sockets to the board or do i connect the arduino to one USB port on my pc and the esp to the other USB port on my pc is that correct
regards
michael

0
BillC35
BillC35

Reply 10 months ago

Michael, you only connect one of these two boards while loading the Arduino code (sketch)
The IDE only recognises one board type at a time.
You will need an adapter for the Arduino Pro Mini (if you do not have one already)
see eBay item #264206118002
The ESP32S does not require any other device other than an USB cable.

0
andydgrand
andydgrand

Question 10 months ago on Introduction

Hi, I'm part way through this build. The ESP32 creates a network. I'm now not sure how I get the Arduino sketch on the board. Do I need a ftdi adaptor/programmer? Or can I do it through the ESP32? Thanks Andy

0
BillC35
BillC35

Answer 10 months ago

Yes, you need an USB to TTL adapter to programme the Arduino Mini Pro such as ebay item # 264206118002

0
andydgrand
andydgrand

Reply 10 months ago

Hi I've successfully uploaded both sketches I think. The DCC Wifi is created and I can connect. However once in the phone app it says Check wifi each time I try to do something and don't get a response. I've attached a picture of the build when powered up. Any thoughts?

20191109_222531.jpg
0
BillC35
BillC35

Reply 10 months ago

Hi, all looks very good and neatly done.
After initial WiFi connection on phone, please try closing App then open again. You may have to press the 'Start' button a few times to establish connection. When the name of the WiFi connection appears in place of "DCC_WiFi' the connection is ready. Try the controls even though a message may still appear to say 'Check WiFi' - this will normally go away once started.