Author Topic: 64 channel modular control system  (Read 3265 times)


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64 channel modular control system
« on: December 26, 2013, 04:51:03 am »
I was asked to built a control system that could switch up to 64 channels on a model railroad to iluminate the houses. To make the effect as realistic as possible, the channels should be switch on and off by a randomized function.

I decided to implement this by with a Digispark. I really love the result of this project and decide to share it here with you ... maybe you can get some inspirations from it.

To make live easier I decided to put the Digispark on a new breakout board with 4 I/O pins and an I2C bus.

Then I designed an interface board with a PCF8574 on it to expand the I/O ports. I want to make it as easy as possible to configure the base address for it and used pull down resistors and a DIP switch for the high level on the configuration pins. I also added a second I2C connector to make it simple to connect another interface (or any other I2C device) The board also contains a ULN2803 to boost the 8 channels of the expander. This darlington driver array can provide up to 500 mA. This is more then I could take from the Digispark and so I added a 7805 to the board for its own power supply.

The 8 channels are routed to two terminal strips. The output of 5 V is of course to much for a LED and so I designed a adapter board with some resistors on it.

The stackable headers of that board can be put into the terminal strips of the interface board.

The big advantage of this approach is that this resistor board can be replaced by an relais board for example

I'm currently working on a 8 channel MOSFET shield to extend the flexibility of that system.

Please let me know your thoughts on that project.


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Re: 64 channel modular control system
« Reply #1 on: January 03, 2014, 02:17:02 am »
A very well thought out project.

This probably has various other uses as well.
Thanks for sharing