DCC-EX Simple Throttle

To accompany my mimic panel’s serial throttle (see /serial-throttle/index), I decided a very simple WiFi enabled, palm-sized throttle I could walk around the layout with would be a very handy addition.

Hence the creation of this DCC-EX Simple Throttle.

Note that there is an option to run this on an STM32F103C8 Bluepill via a serial connection instead.

Hardware 

The hardware required is pretty simple, consisting of a Wemos D1 Mini or Lolin32 Lite (which incorporates a LiPO battery connector), a LiPO battery, rotary encoder (such as the KY-040), and an SH1106 compatible OLED (either SPI or I2C).

I opted for a 1.3” OLED for ease of readability, as it’s still small enough to fit in the palm of my hand when assembled with the rest of the hardware.

I have designed and 3D printed a case to suit the specific components I used as well (I have yet to upload STL to Thingiverse).

Component connections 

This table outlines the pins in use to connect to the various components.

Device Connection	Wemos/Lolin32 Pin	Bluepill Pin
Rotary encoder DT	12	PC14
Rotary encoder CLK	14	PC15
Rotary encoder button	13	PA0
OLED SDA (I2C)	23	PB7
OLED SCL (I2C)	22	PB6
OLED MOSI (SPI)	23	PA7
OLED MISO (SPI)	19	PA6
OLED CLK (SPI)	18	PA5
OLED CS (SPI)	5	PA4
OLED DC (SPI)	2	PA3
Serial Tx	N/A	PA10
Serial Rx	N/A	PA9

Software 

The software is located in my DCCEXSimpleThrottle GitHub repository.

This uses the DCCEXProtocol Arduino library to interact with an EX-CommandStation using the native DCC-EX protocol rather than the WiThrottle protocol, ensuring future-proof feature compatibility with DCC-EX software updates.

Installation 

The software is configured to use VSCode with PlatformIO and will therefore ensure the correct libraries are installed when compiling and loading the software onto your device.

If using the Arduino IDE, you will need to ensure platform support for STMicroelectronics STM32 and/or Espressif is installed.

Further, you will need to ensure these libraries are installed:

DCC-EX/DCCEXProtocol
olikraus/U8g2

There is plenty of information available on the Internet at large around how to accomplish installing these items, so I won’t cover that here.

Configuration 

Once the hardware components are connected according to the defaults in Component connections, for the Bluepill platform, no further configuration should be required.

When using the Wemos D1 Mini/Lolin32 Lite, you will need to configure the WiFi credentials and EX-CommandStation IP address and port details for each EX-CommandStation you wish to connect to. Defining multiple sets of details is supported, meaning you can take this to your club or friend’s place without having to reconfigure it every time.

If for some reason you need to use different pin connections, these can also be adjusted to suit.

All user configuration changes can be made by copying the provided “myConfig.example.h” file to “myConfig.h” (note this file name is case sensitive, and Windows users beware an inadvertent “.txt” extension being added).

Instructions are included in the file for updating the various details, but the WiFi/EX-CommandStation options are outlined here for clarity as well.

Configuring WiFi and EX-CommandStation details 

Set COMMANDSTATION_COUNT to the exact number of EX-CommandStations you will set up connection details for.

For each of the parameters, you must provide the exact same number of elements that you defined for COMMANDSTATION_COUNT as shown in the example configuration provided. Further to this, every element aside from the port must be surrounded by quotes "<element>", and each list of elements must be surrounded by curly brackets {<list>}.

When configuring the parameters:

COMMANDSTATION_NAMES is a list of descriptive names to help you select the appropriate one from the menu
COMMANDSTATION_IPS is a list of the IP addresses for the CommandStations, one for each configured CommandStation (even if the same IP is used for multiple, each one must be specified)
COMMANDSTATION_PORTS is a list of the ports associated with the CommandStations (quite likely these will all be the default 2560)
COMMANDSTATION_SSIDS is a list of the WiFi SSIDs required to connect to the CommandStations
COMMANDSTATION_PASSWORDS is a list of WiFi passwords associated with the SSIDs to connect to the CommandStations

/*
Define WiFi connection parameters here
These are irrelevant if using Bluepill and a serial connection
*/
#define COMMANDSTATION_COUNT 2 // The number of EX-CommandStations to define

/*
Define connection options for each EX-CommandStation entry

Each line must have the exact same number of items as set in COMMANDSTATION_COUNT above
Each element must be surrounded by quotes "" and separated by a commad
Each list of elements must be surrounded by curly brackets {}

#define COMMANDSTATION_NAMES {"Example 1", "Example 2"}
#define COMMANDSTATION_IPS {"192.168.4.1", "192.168.0.1"}
#define COMMANDSTATION_PORTS {2560, 2560}
#define COMMANDSTATION_SSIDS {"SSID1", "SSID2"}
#define COMMANDSTATION_PASSWORDS {"Password1", "Password2"}
*/
#define COMMANDSTATION_NAMES { "CommandStation 1", "CommandStation 2" }
#define COMMANDSTATION_IPS { "192.168.4.1", "192.168.0.1" }
#define COMMANDSTATION_PORTS { 2560, 2560 }
#define COMMANDSTATION_SSIDS { "SSID1", "SSID2" }
#define COMMANDSTATION_PASSWORDS { "Password1", "Password2" }

Operation 

When navigating menus, scroll up and down with the rotary encoder, and click the rotary encoder’s button to select the highlighted item.

During operation, there are three contexts on screen to switch through:

“Select server” menu
“Select loco” menu
Throttle screen

“Select loco” menu 

Providing a roster of locomotives has been configured in the connected EX-CommandStation, selecting one from the menu will allow you to control it.

Once selected, the Throttle screen will be displayed.

Not implemented yet If you wish to control a locomotive on the programming track instead of selecting a roster entry, holding the rotary encoder button down for more than half a second will cause the EX-CommandStation to attempt to read the DCC address. Providing the read was successful, the Throttle screen will be displayed.

Throttle screen 

While on this screen, rotating the rotary encoder will increase or decrease the locomotive speed.

If speed is greater than zero, a single click will stop the selected locomotive, and holding the rotary encoder button for longer than half a second will trigger an emergency stop.

If speed is zero, a single click of the rotary encoder button will change direction, and holding the rotary encoder button for longer than half a second will toggle track power on or off depending on the current state.

Also when speed is zero, double clicking the rotary encoder will display the “Select loco” menu. Selecting a different loco will release or forget the currently selected loco.

To do enable a way to toggle lights on and off.