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How to make I2C lines to extend to more than 2000 meters?

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neoaspilet11

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i2c twisted pair

Hello Everybody,

I am having a master - slave project that will connect multiple devices that used I2C protocol for communications.The problem is some devices are very far from the master with distances as much as 2000 meters from the master. Is tehre a way to extend the SDA and SCL lines of I2C to more than 2000 meters?

Thanks

Jack
 

i2c distance

Hello Jack,
You are pushing it with this, but you could probably use this chip:https://cubloc.com/Datasheet/P82B715_6.pdf
You will also get better distance if you keep your clock speed low. Make sure to use twisted pair.
You could also do it with a pair of 8 pin micros, which may give a cheeper solution than a pair of the extender chips. The ones listed above are around 3-4 usd per chip.
Hope this helps you solve it.
Best wishes,
Robert
 

extending i2c bus

I don't think you can extend I2C bus to 2000m, you will be lucky if you had 100m out of it ..
Also, I don't see any relevance between I2C and a twisted pair .. This stuff (twisted pair, that is) has been designed for balanced transmission systems such as for example the RS-422 or the RS-485, and will not be helpful in I2C systems ..

For distances like that you have to use different protocol; maybe MODBUS, based on the RS-485 hardware, will be the right way to go ..

Regards,
IanP
 

how can i see more than 2000 meters

Thanks beebop and IanP foe the ideas. I think I read somewhere that its possible to have such I2C bus of that lenght. I pull the article when I get home. The article however does not elaborate how to do it. If I recall correctly it mentions that the bus capacitance can be extended. Anyway I am considering other communication protocols other than I2C

I am considering to connect the devices to a LAN, but the problem is LAN cards cost too much for the application and I am using only a PIC16F877A micro for all devices. And it will involve a lot of labor, particulary for the networking if the devices should be connected by LAN.

Again thanks for the ideas,

Jack
 

how much is 2000 meters

Well, I suppose I was over doing it a bit, but
What is the maximum distance of the I2C bus?
Click to expand...
https://www.esacademy.com/faq/i2c/q_and_a/faq/i2cqa1.htm
They claim:
clocked at about 500Hz - had a bus length of about 100m (300ft). If you are careful in routing your PCB's and use proper cabling (twisted pair and/or shielded cable), you can also gain some length.
Click to expand...
Although, when I re-read the OP, I see you are looking for 2000m. (whoops!)
However, I do agree that there are better ways of doing it; yes rs485 is made for it.
How complex is the MOD bus?
 

scl protocol meter

Hi
see philips website and i2c ICs
regards
 

i2c bus extender howto

Hi, Simply don't do this. It will be your disaster to come. Better use RS485 with packets and current sources. Then you can use the UART on the PIC. regards, Paul.
 
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