A Guide to the Layout Control Operating System

The Layout Control Operating System (LCOS) is a total control system designed to take advantage of ubiquitous, cheap microcontrollers (computers on a chip) to create highly standardized Layout Control Nodes (LCNs) linked together wirelessly in a Layout Control Mesh Network. A basic LCN consists of a microcontroller mounted on the LCN IO board, with LCOS preloaded and a low power radio for communications.

The preloaded firmware is ready run as soon as you place the LCN on your layout. Connect devices to the terminals, power up the node then then run the LCOS Configuration App (the Configurator) on a Windows PC to find and configure it. The Configurator manages all setup tasks, making LCOS a plug-and-play layout control solution. The Configurator also manages firmware updates.

The design intent is to share loads among multiple LCNs, each functioning independently. A core tenet of LCOS is that, absent a specific instruction from a central source, all decisions are made locally by the LCN without requiring intervention or management by a central processor. Among other things, this unleashes the multitasking power of multiple independent processors and balances the amount of node-to-node communication required.

The capabilities of an individual LCN can be expanded and enhanced with standard peripheral devices that provide additional resources such as digital input ports, digital output ports, PWM ports, and a CT sensor block occupancy detection system. In this way each LCN is easily adapted to the specific needs of the layout section it is tasked to run.

What Can an LCN Do?

A Client LCN can run block detection on up to 8 blocks, run up to 16 signal heads and up to 8 turnouts , manage buttons and switches, control relays, run other lighting and exchange data with other LCNs.

Any LCN can host a control panel, making it easy to set up local control panels around the layout. Since all communication occurs over the wireless mesh network, your control panels need only power and no other hard wire connections to the layout.

The MASTER NODE (address 00) is optimized for creating a master control panel spanning the entire layout.

Layout Control Mesh Network

Mesh networking is a variation on ad-hoc local networking that lends itself to both symmetrical and asymmetrical network topologies. The Layout Control Mesh Network (LCMN) is a routed mesh network built from a set of Arduino libraries for nRF24L01+ radios. Routed mesh networks are efficient but fault tolerance is more limited because they can’t resort to flooding when an intermediate node is down. However, in the context of a model railroad layout, if a node is offline for modeling or repair reasons, the most important thing is that everything else continues to function until the node comes back. Adding or removing nodes is easy with the help of the Configurator.

Topology is generally hub-and-spoke, using a MASTER node as the top hub uniting all the branches beneath it. The MASTER can have up to 5 children, as can each child. The depth of the topology can be up to 5 levels (including the MASTER), which results in up to 781 addressable nodes on one radio channel. Really large networks can be achieved by running multiple parallel networks on different channels.

LCMN Structure and Addressing

The address of an LCN is a number in OCTAL format that describes the route from the MASTER to reach the node.

The MASTER Node is always 00.

The Master Node can have up to 5 children. The address of each child node is 1 through 5 with a leading 0 — 01, 02, 03 , 04 and 05. These are generally referred to as Level 1 addresses.

Each node can have 5 children of its own, whose addresses are Level 2. The address of each child is 01 through 05 preceding the address of its parent. So, the children of node 01 are 011, 021, 031, 041 and 051 respectively. The entire tree can have up to 4 levels below the Master. This can be illustrated as follows:

rRF24L01 Mesh Network Topology and Addressing

The last possible valid network address is 05555. LCOS uses addresses outside of the 00 – 05555 range to represent connections to objects outside the radio network.

Getting Started

First, See the Layout Planning Guide for detailed guidance on planning your LCOS installation.

Second, using the methods and considerations explained in the Layout Planning Guide, develop a plan for distributing nodes around your layout.

Third, buy the LC1 LCOS Layout Starter Kit, containing a MASTER NODE and one CLIENT NODE. You can buy more Clients if you need them, or later when you are ready to deploy them. If you are planning a big layout, get the LC2 Layout Foundation Kit instead.

Fourth: The Configurator App is automatically included in your Starter Kit purchase. Follow the downloading instructions and unzip the app in a convenient place. See the Guide to the LCOS Configurator.