Types of cabling for connecting components to arduino

I'm using an Arduino Uno and I'm trying to connect a RFID-reader with cables to the Arduino. The Rfid -reader has 8 pins. I tried 8 separate cables with a length of about 6 meter and a diameter of 0,2 mm. It did not work. I'm wondering if it was because of the length or diameter of the cables. What is the best type of cable I can use for such a connection?

Did it work when connected directly to the Arduino?

We will need information on the RFID reader.

Weedpharma

The RFID-reader I use is RC522, working with 3,5v.

and yes it is working, when I connected it (via a breadboard) to the Arduino. It worked again after I shortened the cables to a about 3 centimeters.

Here is the documentation on the device

http://www.nxp.com/documents/data_sheet/MFRC522.pdf

What interface are you using to communicate with it?

Weedpharma

Hi,
Are you using the cable to supply power to the reader?
If so, because the reader pulses RF, you might try a 470uF or 1000uF capacitor across the power supply pins at the reader.
This will provide storage for the pulse current and not rely on the wires to conduct all the pulse current.

Tom.... :slight_smile:

I2C will be pretty much impossible at that distance without special driver chips and a lot of attention to the cable type and layout.

SPI is unlikely to work either although I have managed to get high-speed SPI working reliably in a harsh environment at 3 metres.

TTL Serial should work, possibly at slower speeds like 9600 baud, but it's likely to pick up a lot of interference so you need error-detection at both ends.

MorganS:
I2C will be pretty much impossible at that distance without special driver chips and a lot of attention to the cable type and layout.

I am using ~8meters of Cat-6 between three I2C devices. Mega at one end, two devices at the other end.
Running 24/7 at the default 100Khz speed, without hickups. With 3k3 total pull-up resistance.

Don't run clock and data on the same twisted pair.
Run clock e.g. with ground, and data with supply or with a second ground.
Leo..

:slight_smile: I Shortened to 2,5 m and use a 470 uF condensator (I assume that is the same as a capacitor). It worked! Thanks for the advices, though a few were to technical for me. Never thought of to supply the power directly to the device. Maybe that is more stable. I suppose in that case it is still necessary to connect the ground of the device with the ground of he processor.

Are you using shielded cables and grounding the cable shield?

Cat-6 (Ethernet/Giganet) cable, with a low capacitance of ~51pf/meter, works fine for I2C.
Standard I2C can handle a max bus/wire capacitance of 400pf with the right pull-up resistors.
Cat-6 has four twisted pairs.
Use one twisted pair for data/ground.
Use another pair for clock/ground.
Two pairs left for supply and whatever.
Leo..