OpenServo.com

[anarchy_uk]

Hi,

I'm Andrew, currently studying for my A-levels. Came across this site by chance but it looks to be an amazing project and just what I needed, the majority of my A-level design technology course is project based, and I'm designing a "robotic" arm (I hope to have it manually
I have a fair bit of CAD experience via Solidworks and Cobalt, and some limited electronics knowledge (I've used circuit wizard).

So after looking through a lot of the documentation I have one question...

I've seen the I2C usb interface, is there a way to control multiple openservos from 1 usb port? or have I missed the point completely... never the less should such a solution exist any links would be great!

Many thanks,
Andrew

[ginge]

Hi Andrew

Welcome to the OpenServo project!
We have users that use OpenServo to drive a robot arm, so they are more than suitable. As for the USB to I2C interface, yes, you can drive up to 127 devices from it, OpenServo or generic I2C device.

I wish you well in you project, keep us up to date, and do not hesitate to ask anything that may help you out.

Cheers,

Barry
_________________
http://www.headfuzz.co.uk/
http://www.robotfuzz.co.uk/

[anarchy_uk]

Thanks for the warm welcome, you lot all look far more talented than me, don't suppose there are any circuit diagrams for I2C distribution (1 usb connection to many outputs) anyone can point me towards?

Andy.

[ginge]

Hi Andrew,

The I2C protocol is a daisy chained bus protocol which means that you can take many connections off the one set of wires.

|USB-I2C|-----|device|-----|device|-----|device|----etc

The picture on this page says more than the god awful ascii art above. It also gives a nice overview of the protocol.

http://www.esacademy.com/faq/i2c/general/i2cproto.htm

If you need a schematic and PCB for the USB to I2C adapter, you can use the one on my page here:-
http://www.headfuzz.co.uk/?q=USBtoI2C

So to connect many devices to the above interface, you would just run a cable from the adapter and take a spur off to each device.

Cheers,

Barry
_________________
http://www.headfuzz.co.uk/
http://www.robotfuzz.co.uk/

[wurpfel]

also a warm welcome




when you mix OPENSERVO and maybe I2C-sensors be aware that`s only 112pcs may be adressed. the rest is reserved for special proposes

like.... the switch to the extended protocoll up to 10bit, aka 1`000 devices

details see here:
http://en.wikipedia.org/wiki/I%C2%B2C



it`s exist a full spectrum of busnodes and -masters, AD-devices, encoders, IO-switches, all kind of sensors and some VGAcams with I2C output...

it`s also very simple to made a I2Cbusnode off own logic, like a doorsequencer for a modelairplane


I prefere the I2Cbus to elliminate the wire-bush in my models and cure EMC problems due on heavy-wire-forrests.
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[anarchy_uk]

Thanks for all the help, I'll be sure to keep you updated with my progress. Being able to daisy chain devices will make my task a lot easier, now I just need to look into some I2C controlled relays.

[ginge]

Hi Andrew,

I don't know if this off the shelf I2C relay solution will help you at all...

http://www.robot-electronics.co.uk/htm/rly08i2c.htm

It looks reasonably priced too.

Failing that you could use something like the PCF8754 I2C port expander to do drive a transistor to trigger the relay...

http://focus.ti.com/docs/prod/folders/print/pcf8574.html

Cheers,

Barry
_________________
http://www.headfuzz.co.uk/
http://www.robotfuzz.co.uk/

[anarchy_uk]

Exactly what I needed, I better be careful or you lot will do the whole project for me

[Jiellen29]

Hello,

I am a newbie here,i learn a lot from this site,thanks for the great info you shared here...

Have a great day to all!!
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