July Update

July has been a quiet month as I have been off colour with some bug that drained my energy for around three weeks.  I had to cancel the scheduled scenery construction day. The newest member of the operating team Pierre has been over for two training sessions.  Derek has also been over and had his first training session on working the upper level main control panel. Wayne has also been over for a discussion about using the LaunchPad for some projects on his layout. Apart from thinking and doing a bit about my signalling concept not much has happened. Planning for the Ops Session on Monday 4 August has commenced. I am sorry to report that the video of the Grand Opening promised for this month will not be completed until next month as the author has been dealing with a family bereavement.

Signaling concept design

Last month I gave you this link  to look at the concept details. This month I have been developing the full use of the MSP430G2553 chip, selecting components, testing components, proving detection concepts, building a trial project and testing the completed concept project. This was followed by developing the Junction signalling module design further and commencement of building the board to test the design. I am also deveolping a board to isolate the MSP430G2553 rnning on 3.3V DC from the inputs (DC 12 V & Frog DCC) and the outputs (12V DC).

Full use of the MSP430G2553

In all the LaunchPad projects that I have seen to date only part of the chip has been used.  The four PINS used for various communications links have been avoided. Signalling is input/output intensive so I researched the use of these pins.

Two good reference sites were found Energia and ARGENOX and my concept designs have been modified to make use of the four additional pins.

PIN numbers and corresponding Logical PIN designations

Component Selection

I experimented with various ambient light photodiodes and phototranistors and have found the ones which seem to work well is the ambient light version (Osram SFH 309 5/6) of the IR ones used for the Grade Crossing Project. I have discovered that the degree to which components vary the voltage and current between off and on states affects compatibility with the MSP430G2553 (MCU) chip.  to obtain a "high" the voltage applied to the MCU PIN needs to be within 0.3V of VCC and I am using +3.3V.  The first three components I tried gave a maximum of +2.7V and did not work.

Testing the selected components

The ambient light detector test..

Proving the detection concept

The direction sensing at each end of an electrical detection block using pairs of detectors.  It uses an idea developed by Hoffy in his speed trap project.

The completed pilot project

The design...

The operating pilot...

Junction Development

The five tracks at the junction result in seven routes that can be set.  The design calls for the first MCU to analyse the turnout states and identify the available routes for use by the East>West and West>East signal controlling MCU's.

The theory is that the MCU's will provide a "Red" inputs to the 3 aspect signal modules for all routes that are NOT available.  The signal modules with then work the normal R-Y-G logic.

Integration of Route states and block occupancy to establish "Red" signal conditions for trains heading West.

Integration of Route states and block occupancy to establish "Red" signal conditions for trains heading East.

The work on the hobby board has commenced.

When completed I will post the LaunchPad code for other to copy and adapt should they so desire.

Isolating the inputs and outputs

All of the Signal inputs and outputs are at different voltage potential so I will be isolating the circuits with Optocouplers.  I will need several banks for the concept trial..This board will have three sets of four banks of five.  The male header pins were secured using Superglue (ACC).

This board will be home to 60 Optocouplers!

Two styles of female headers Input and Output

Input side of the Optocouplers taking the frog DCC power state (Normal = no circuit Vs Reverse = power on) the 1k0Ω 1/4 W resistors to limit current to approx 20 mA.

Output or LaunchPad side of the Optocouplers using a 330Ω 1/8 W resistor to limit current to 10 mA Red wire is VCC (3.3 V) and the Green wires will connect to the input pins for Blocks 1 - 5.

Both female headers installed on the Vero board male headers.

Ops Session Next Monday

Invites sent and confirmation of attendance requested.  I am thinking of having a less complex session unlike the grand opening.  I have offered operators to do something different this time around. I think I will schedule more yard work and less mainline movements this time.

I made some cheat sheets to assist with checking where things are on the layout.

That's it for this month.


Thanks again to those that continue to help me achieve my ambitions and hello once again to all my followers!


Till the end of August.

-ooOOOoo-