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• The GCA modules

Hardware by Peter Giling

The GCA101v1 was ready for an update.
Since DC power supplies are getting cheaper, this unit does not need a special on-board power supply.
So the new design is smaller and fitted with a very compact and good quality switching regulator for the 3.3V.
Furthermore, the complete design is only changed where it comes to power, resulting in a smaller unit.

• Solid GCA-Compatible power supply
• Isolated coupling between PC and Ethernet
• On-board ICSP for easier development and self programming of ATmel processor
• 2 x RJ12 connector for Loco-I/O periferie
• 2 x D-sub9 connectors
• Clear on-board indication of present power and Ethernet/Loco-I/O functions
• Entirely compatible with all Loco-I/O PE commands
• Fully supported by Rocrail

Only dc power is allowed.
Power supply : 12Vdc minimum 3 Amp.
GCA can provide you with a good and small 230V to 12Vdc supply.
Please refer to pricelist.

The GCA101 is equipped with a special Ethernet connector.
It provides an electric isolation , which means that computer and your trains are not electrically connected together.
The standard Ethernet cable can be one of the two types. Either normal or 'crossed' cables are useable.

Connecting GCA101 to PC is best done by means of a router in between.
So your home network will be one way to do it.
If you do not like this situation, use a dedicated cheap router for it.
Direct connection GCA101 to PC is possible but requires some experience with networking.
One important mark to old left-over routers:
Routers previously used at home with your previous Internet/ Tv provider, will experience problems with connection via UDP.
This is probably caused by the UDP channel inside the router, which should be opened by passwords/codes/pin numbers.
In this case, that router is unuseable.

One other problem might cause no connection in Windows.
The ethernet module in you pc might be not the only one.
In that case Windows sometimes has a problem to decide where LocoNet communication should be sent to.
Best way to solve this, is tot find out which inside ethernet adapters are not used, and shut them off in Windows.

Two processors on this board are installed.
One to connect Ethernet to the standard SPI and the second as interface between SPI and Loco-I/O.
The unit is equipped with two Loco-I/O RJ12 connectors and two D-con-Loco-I/O connectors.

Unit is available as board only or as complete parts package, including programmed processor.
Ready built units will not be available.

1. First start with all resistors and IC sockets.
2. Then small capacitors and small elco's. Remark: 15 pF capacitors have indication 15j.
3. Then all connectors, leds and fuse.
4. Before inserting U1, U2 and U3, test power 3,3 Volt on pins 1 and 8 of U3.

GCA101 also can be used with TCP.
Processor should be changed to ATmega328P.
Firmware is developed in Spain by Dani Guisado and downloadable here: ​https://github.com/ClubNCaldes/GCA101LbServer
Website of Dani is also very interesting : http://www.clubncaldes.com/
Leds blink when waiting for a connection from Rocrail.
When Rocrail is connected, Led2 and 3 show Loconet activity (send and receive) and led4 Ethernet activity.
Standard Ethernet address: 192.168.0.200.
Other IP addres can be pre-programmed in INO file before programming the chip.
These adresses are stored in EEprom from address &H0000 to &H000B :starting with GCA101 address, GCA101 sub address, gateway address.
On ordering kits, you can also inform me with your internal Ethernet addresses, so it can be programmed in the processor for you.

The U1 pins 23, 24 and 25 must be connected to pin 22.
Those pins are used for selecting an IP address preset but are floating on the GCA101v2 board.
By connecting them to ground the IP address stored in the EEPROM is used.

Communication needs to be set as LbServer in Rocrail settings > controller:

This is the most recent .hex file for U1

Thanks to Robert Evers & Fred Jansen who have put much energy in getting the system up and running, you will finally be able to run Rocrail and Loco-I/O without USB and/or RS232.

The communication between Rocrail and the GCA101 is by the User Datagram Protocol. Therefore, only the LNUDP LocoNet interface type is supported.
Setup Rocrail with the exact values shown below except for the Local IP address which is in most cases not needed.
The GCA101 own IP address is not used in the Rocrail setup.

	In case GCA101 is not the first controller in your setup, do NOT forget the correct IID !

This is the Multicast address to use for communication and must be set to the FIXED value of 224.0.0.1.
– The All Hosts multicast group addresses all hosts on the same network segment. –

The service port must be set to the FIXED value of 1235.

LNUDP is used as standard.

Only required if the PC has more then one network interfaces installed; In all other cases: Leave empty!
IP address of the PCs network interface which is used for communication with the GCA101 to make sure the traffic runs on the right one.

• For the previous version of GCA101 please refer to this page