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GCA185 Arduino Shield for LocoIo (LocoNet compatible)


By Peter Giling


Dani Guisado in Barcelona ( ) found firmware to make an Arduino Uno function as a LocoIo module.
With addional work within this firmware, he changed that to make it act like a GCA50
But of course a small interface was needed to adapt to the LocoIo invironment.
He started the experiments by using a modified GCA50 as an interface, and that prooved to be fine.
So I made this shield for Arduino Uno, and provided it to Dani as a base of further experiments.
You can read the results of that on his web-site.
This board is now available in the same quality as you are used to from GCA.

And making it function like a LocoIO module, it again expands the always growing possibilities of Rocrail.

The prototype

The first prototype has been seriously tested in Spain.
(and prooven allright)
The professional board is available now!
The LNet shield with its motherboard

The hardware


The two jumpers onboard are used to specify where power for the GCA185 and the underlying Arduino Uno is coming from.
Basicly, GCA185 is supplied with 12V from LocoNet bus.
If Arduino Uno should also be supplied that way, there are two options.:

Jumper position Task remark
JP1 installed 12 Volt going to Vin of Arduino Uno Arduino Uno does not need any further supply
JP1 not installed VIN of Arduino is not connected to GCA185
JP2 installed 5 Volt from VR1 is used to supply GCA185 Arduino Uno does not need any further supply
JP2 not installed 5 V for GCA185 comes from Arduino Uno Supply from VR1 is only used for J5 and J6 interface connectors.

Further questions? Ask Peter.

Firmware for Arduino

The Arduino Uno sketch
More info about this development can be found at

gca185-en.txt · Last modified: 2018/11/26 02:27 by rainerk