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I2C Maximum wire length

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Computerman29

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i2c length

Hello,
I am designing a device that uses a PIC to flash goggle-mounted RGB LED's with adjustable rate and brightness. I was considering using I2C or SPI to drive the LED's from an I/O expander also mounted on the goggles. Is this a viable idea, or is there a maximum wire length for reliable operation? Thanks in advance for your help.
 

sunish

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i2c cable length

hai
i checked a lot for this
i found from the philips this.
the maximum cable capacitance is limited to 500pf
a cat5 cable has the capacitance of 17pf/feet
anyway i think it's possible to use I2C in small distance communication.

regards


sun
 

ric_vas

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i2c max length

There's a PLC maker in my country that states one of its equipment can connect to some sensors up to 1km far away using its onboard i2c channel.

I have no idea how this can be achieved. Low frequency???

Ric
 

manish12

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i2c maximum length

Dependes upon noise margin of the rxd circuit .
 

VSMVDD

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i2c wire length

I2c is data level

you simply add buffers to rework the signal levels

every so often

or you use an amplifier and a comparitior to rework it back to real data
when at distances ....

i2c error checks
so this isnt a problem

its there or its not like digital TV

appart from this

copper wire is around .12R per meter for a single telephone style cable core

so simply work it out using resistivity of the cable and its lenght
against the driving voltage
so you can calculate the output voltage
against the current you need to switch your distant device

if its less than you need simply use a cmos gate to buffer it or cmos ttl

they are very sensative high impedance inputs
and need micro amps to switch them
most often pico amps


i would use an rf pic if you have little distance to go

or if its a vast distance use the net and a ip stack controller
 

alzomor

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i2c maximum distance

Hi

It depends on your speed , supply , pull up resistors , bus & load capacitance.

just serch the net for USB specifications
it's a fill from philips with all the data you need

Salam
Hossam Alzomor
www.i-g.org
 

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