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I’d like to connect the bluetooth components to the FEZ board over a long disatance using Cat5. Is this possible? What are the distance limitations of the I2C protocol over a wire like Cat5?



bluetoothe…I2C…cat5…these are all not related to each other so I am not sure how I can help :confused:

Same as using any regular wires. Using cat5 will not give you any further distance on I2C.

For long distances, you can use RS422 or RS485

Instead of the questions you have, it is better to tell us what you are trying to accomplish then we will give you a better answer if we can.


I only wanted to use Cat5 because there is a network connector in the kitchen that goes to the basement where the FEZ mainboard will be installed. My Bluetooth barcode reader won’t send a signal all the way to the basement so I want to bring the FEZ Bluetooth component closer to the reader by placing it in the kitchen and then use Cat5 to get the signal back down to the FEZ board in the basement.


I see… Bluetooth has nothing to do with equation. You want to transfer data from the basement to the a module…this module happened to be Bluetooth.

Now, where I2C came from? Bluetooth modules are usually serial (UART).

You can transfer UART data fro long distances if you keep the baud-rate low, maybe 9600. Or you can use RS422 or RS485 transceiver whit your cat5 cables and then you will be able to transfer data for very long distances!

Your cat5 cable have twisted pair and you can only take advantage of this if you use RS422 or RS485. See this if you want to learn more


I thought I saw that your Bluetooth FEZ component connected to the FEZ board via I2C. Maybe I was wrong on that. I’ll look again.


Looks like maybe I assumed wrong. Your web page doesn’t give any detail on the Bluetooth component but it looks like serial. Maybe I could mate your component with a Wiznet serial/Ethernet gateway ( and grab the barcode readers strings that way. The reader emulates a keyboard I think so how do I get your Bluetooth component talking to my Bluetooth barcode reader?



You could but why spend all the money? Just do UART at low baud rate and it should work.


You mean I could just connect my Cat5 in the kitchen to your Bluetooth component and then at the other end connect the Cat5 to the FEZ board?


Yes. Start with low baud rate then go up to see how fast you can go on your wires.

You can short TX to RX your living room then connect FEZ in basement. Then you can send a string and you will receive it back (through the wires).
If the data match then you are good to go…add the bluetooth component.


Excellent. I was making this far more complicated than I needed to just send a string 20 characters long fron the barcode reader down to the basement via Cat5. A couple more questions.

  1. How is your Bluetooth component powered. Is it via the Cat5 from the FEZ?

  2. How do I connect your Bluetooth component to my Bluetooth barcode reader. Do you have some sort of Windows based utility that sniffs for all Bluetooth components in range and then allows us to mate the two components?



The Bluetooth module works with PC where you search for it, find it and connect to it. I am not sure how would it connect to the bar-code reader. I am assuming your bar-code reader is Bluetooth.

Some bluetooth modules have built in command that let you search and connect to devices. ours doesn’t I think.

I was assuming you already had it working and now want to go through the cat5 cable!

Why not use a USB barcode reader whit USB cable extender? like this one,140,120


Actually that is a very good idea. I’ve found many USB Bluetooth tranceivers that include the needed utilities to mate the transceiver to a specific Bluetooth devive like my barcode reader.



Hmm one more thought. Will that USB extender plug right into the FEZ? What about FEZ Cobra which I expect I will go with because the Chipworkx doesn’t include a baseboard.



It will work with all our devices (assuming the extender makers flowed the USB specifications correctly :))