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Multiple Wiring boards via 1 code window (Read 9238 times)
04/28/06 at 00:17:30

aimee   Offline
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How can I control more than one wiring board from the same code? I figure I'll need to specify which USB serial port each wiring board is connected to. How can I add the names of other  USB serial ports on my computer? Can I use a hub? Can I controll child wiring board(s) through a parent wiring board? I ask this because I built a device which needs 100 separate I/O pins. Thanks!
 
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Reply #1 - 04/28/06 at 01:25:06

Alan_Kilian   Offline
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How about adding some chips th expand the number of I/O pins and controlling them from one Wiring board?

I ran a system that used 1372 I/O pins. http://taomc.com/stepperarray/stepperarray.htm

If you are interested in just expanding the number of I/O pins, I can talk you through it.

What are you trying to do? That will help me pick how to expand the I/O pins.

Are you driving high-current things like lights or motors?

Are you driving low-current things like LEDs?

Are you going to need to turn the things on and off very quickly, or just slowly?
 
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Reply #2 - 05/02/06 at 00:00:07

zambetti   Offline
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Perhaps have a look at the new Wire library in 0006

http://wiring.org.co/reference/libraries/Wire/index.html

The Wire library enables you to have up to 128 boards/devices talking to each other via a common bus of two wires (and one additional wire for ground).

The simplest way to get started is to set up one board to act as a master requesting and transmitting data to one or more slave boards.

Code examples for setting this up are included in 0006 and information for how to wire this up is in the reference page linked above.

Note: for small buses (less than five devices) you do NOT have to solder the jumpers mentioned on that page.

There are also port expander chips available that work over i2c/twi like the MAX7300. If you want to try your hand at getting it to work with the Wire library, we would love another example to add to the next release : )
 
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Reply #3 - 04/14/07 at 06:23:53

worksofman   Offline
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Hello all -
I'm wanting to do something along the same lines.  I'm creating piece of public art which will include around 450 RGB LEDs.  (Actually, 3 of them).  I realize that's actually 1350 LEDs each...

Likely I'll  build a smaller system first, as a proof of concept, but I'd love a nudge in the right direction from those who know... 

It looks like this could be done with a single board, and adding chips to expand the I/O.  Looking at what Alan_Kilian has done, and a few others out there, I know it can be done...  but is the best way to do this is build it as a matrix?  As individual channels?  Groups of matrices?  I want the full range of colors, so it seems PWM is needed, as far as I can see.  It even seems like there's a lot of chips that can handle this, if my reading of TI's and Maxim/Dallas's websites are correct. 

The final result I'm looking for is individually controllable LEDs, to create both pre-programmed lighting sequences and some reactive sequences, the latter using sensors, etc. 

Primarily I want this to be a stand alone system. I like what Processing could bring to the work as well, but since this is an outdoor piece, not having a computer attached all the time seems the way to go (and keeps the budget better...).

I'd love any thoughts or input!
Matthew
 
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Reply #4 - 04/16/07 at 01:23:46

barragan   Offline
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hi, yes that's probably the best direction to take, those MAXIM chips can be cascaded and will drive things like power and brightness etc. which in other ways are very difficult to tune. I have added schematics for it to the Matrix example: http://wiring.org.co/learning/examples/hello_matrix.html
 
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Reply #5 - 04/16/07 at 05:29:02

worksofman   Offline
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Thanks, Hernando.
For more background info:  Even though it's going around a cylindrical  device, it would essentially be set up as a 20 x 28 grid...

So you do think a matrix would be better than discrete LEDs?  It would definitely cut down on the number of I/O's needed -- but would it make programming imagery/sequences that much harder?

For the sake of the various chips, can I reprogram  the Wiring board to have more than one TWI interface, or is that a limitation of the ATMega128 itself?

 
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