New version URB 2.7 released 10/15/17

Universal Railway Bus unit is first and foremost a convenient and reliable connector, replacing the breadbord and a bunch of wires. A more important feature of URB is the integration of several blocks into a chain, and on this basis the construction of any electronics for layout and control. In other words, it is a universal controller for railway modeling electronics.

Sketches for URB you will find on Arduino Central. So, you can send commands via the I2C bus to any of the end peripherals connected to any URB on the layout. According to the specification, the maximum length I2C bus when using a twisted pair of about eight meters. In practice, with a total cable length of five meters, everything works correctly.

Two serial ports provide the ability to receive commands from two different control devices, or a toggled control from one independent line to another control 2 trains without DDC. For example, if you insert two Bluetooth modules (like HC-06), two gamers on Android smartphone’s can independently control trains using the full version of the ArduinoTrain BtControl Pro app. By using USB, you can manage the layout directly from your computer. Also, you can also use the control of DDC and URB as service block together.

Pullup resistors

The I2C bus needs resistors pulling the data line to a high potential. You can install resistors of any type on the board. I recommend 10K resistors.

Solder bridge

If you do not use outputs with high current load, then ULN2003 is not needed. In this case, for your convenience, on the back of the board jumpers are provided, by closing them with a solder, you can connect the periphery to the screw terminals of the SP4 connector instead of the needles of the DP1 connector. Also you can solder to this place SMD resistors.

URB 2.7 boards

Current version PCB: 2.7

Make URB
URB 2.7 add 12V

Add 12V supply

New function URB 2.7. The orange pin of the connector SP2 is connected to the pin Vin Arduino NANO. With this connection, you can only use 12 volt pennies. This is done for remote connection of URB. There are restrictions (see example REMOTE CONTROLLER).

Make URB

URB connectors


Features URB

This board uses Arduino NANO. Therefore, the dimensions of URBs are only 60x70 mm, which makes it possible to hide it even inside model building. This solution provides excellent flexibility, maintainability, simple mass production and low cost.

All features Arduino Nano, plus:

  • Connectors for two Bluetooth HC-05 (HC-06) modules
  • Direct plug 3 servos
  • Direct plug 3 any Arduino sensors, jumper DP5 is ON
    (temperature, Hall magnetic, light, IR and etc.)
  • Direct plug relay block
  • Direct plug motor-driver aka L298 or similar
  • Convenient screw connections
  • 6 (7) High-Current outputs (Up to 0.5A per channel)
  • High-Voltage Outputs up to 50 V
  • Reliable data exchange between the MCU (like Raspberry Pi) using 3.3 volt logic and Arduino
  • Built-in I2C bus
  • Two mode screw connections D2-D7

Optional: install I2C pull-up resistors and smoothing capacitor for power supply

As you can see, the board is set only passive connectors without any electronic components. But here there is nothing to break! By plugs Arduino components to URB, you get many various options for connecting to the railroad peripheries. You can even set empty URBs along the entire length of the builded layout, and then, if necessary, install the Arduino components in them.

URB to PC connection
Rail Unit
station control panel
URB 1.3
lights on  layout
URB 1.8
railway crossing barrier gear
Prototype II
URB 2.2
URB 2.7
All details for this project are here

URB details

  1. PBS-15 (HO27): 2.54mm pitch PCB female single row 15 pin - 4 pieces (or 15 pin - 2, 6 pin - 2, 4 pin - 2).
  2. PLS-40: 2.54mm 40 pin male single row pin header connector - 1 piece.
  3. DIP IC Sockets 16P - 1 piece.
  4. 2 Pin screw PCB terminal block connector 5.08mm pitch - 6 pieces.
  5. 3 Pin screw PCB terminal block connector 5.08mm pitch - 4 pieces.
  6. ULN2003A (DIP16 package): High-Voltage, High-Current Darlington transistor arrays - 1 piece.

URB accessories

Arduino NANO and optional 3.3 to 5V level converter and 2 bluetooth modules HC-06(05).

HC-05 and HC-06, in fact it, is absolutely identical bluetooth modules with identical chips. One of the chips of these modules is a microcontroller. On the HC-05 there are two additional pins for its programming. There are no such pins on HC-06 and its module is easier to use for my project.

Make URB

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