All components used for building ARC1 will be introduced in the following. To make shopping easier, I collected some distributor links with prices. I will try to keep the component lists, links and prices as up-to-date as possible, but due to the “prototyping” nature of some of the parts, availability won’t be assured forever. Luckily, in most of the cases replacement parts can be found easily. With small changes to the firmware, they can be supported in future releases.

Not all of the components listed here are necessarily required to run ARC1. If you don’t plan to use Bluetooth – just ignore it. The same applies for the LED ring around the speed control dial. No changes in soft- and hardware are required if you just don’t connect those components.

The Controller’s Base Board

The centerpiece of ARC1 is a development board of ST Microelectronics. It’s based on an ARM Cortex-M4 microcontroller (STM32F429ZIT) and is shipped with a 2.4” Color TFT-Display with resistive touch. Contrary to other popular development boards (such as Arduino, Olimex etc.), this ST board offers easy access to all I/O pins, provides an onboard programmer  / debugger and offers great value for money. The board can be supplied with power either via USB or via a separate 5V input pin.

All technical details and comprehensive documentation (manual, schematics, Gerber files, BOMs etc.) can be found on the manufacturers website.

STM32F429 Discovery Kit	Distributor	Price
	EXP-Tech	37,95 €
	Farnell	28,66 €
	Digikey	26,88 €
	RS Online	26,38 €
	Mouser	28,15 €

Speed control dial (encoder) and LED ring display

An encoder is necessarily required by ARC1 for speed control and in order to navigate through the GUI. You can use almost every available rotary encoder with A/B signal outputs. If it also provides an integrated pushbutton, the better, as it will make menu navigation much more comfortable. Of course this pushbutton can also be external from the encoder.

An optical representation of the locomotive speed can be provided by two supported LED ring displays.

Alternative 1	Distributor	Price
Sparkfun Breakout Board	Sparkfun	No longer available
Sparkfun LED Ring	Sparkfun	No longer available
Sparkfun Illuminated Rotary Encoder	EXP-Tech	4,25€
Sparkfun Encoder Breakout Board (as replacement for the no longer available breakout board with LED ring)	EXP-Tech	3,10€
Adafruit rotary knob	EXP-Tech	4,35€

Alternative 2:	Distributor	Price
Seeed Studio Grove Encoder	EXP-Tech	4,50 €
Seeed Studio Circular LED Ring with 24 LEDs (Optional)	EXP-Tech Seeed Studio	11,85 € 12,90 $
Connecting cable (recommended for Seeed Studio Grove Encoder and LED Ring)	EXP-Tech	3,89 €
Adafruit rotary knob	EXP-Tech	4,35€

Bluetooth-Interface (optional)

The Bluetooth-Interface allows controlling ARC1 and thus your model railroad with an Android portable device. In general, all Bluetooth-modules providing SPP (Serial Port Profile) can be supported by ARC1. Because SPP is based on the Generic Access Profile (GAP) and is thus provided on almost all Bluetooth modules, this should be no issue. However, there are only a few Bluetooth breakout boards that work in SPP mode by default and don’t need extensive initialization effort. The presented Bluetooth-Bee module is based on HC05/HC06 modules and is a great breakout board. The connection to the ARC1 base board can be done by jumper wires, but caused by the very short pins, soldering would be the preferred solution for once.

Seeed Studio Bluetooth Bee v2.0	Distributor	Price
	EXP-Tech	17,85 €

Accessories

For interconnection of the components, using so-called jumper wires is the preferred and easiest solution. Those wires are shipped ready-for-use and can easily be plugged to pin headers without soldering. The minimum length of the jumper wires should be 150mm and both sides should be female (F/F). Jumper Wires can be obtained from almost all electronic shops and distributors but prices can vary considerably. Best value for money is given by jumper wires that come as a ribbon cable – and you also have the choice of keeping a part of the ribbon when having multiple data lines per module. Some alternatives are presented in the following:

Jumper Wires (Alternatives)	Distributor	Price
F/F 200mm Jumper Wires (40 Pcs.)	EXP-Tech	4,20 €
F/F 150mm Jumper Wires (10 Pcs.)	EXP-Tech	1,79 €
F/F 250mm Jumper Wires (13 Pcs.)	Conrad	5,99 €

 

Image sources: manufacturer or linked webshops.