First of all I apologize if I have posted this in the incorrect place. I am hoping to get some help and or advice concerning a connection issue I have been encountering. I have searched trying to find some discussion of this issue with no success. Any help would be greatly appreciated.
The project I am working on is using a Nano and an Nrf24L01 radio module. Everything works perfectly connected with Dupont wires, but when I add an RJ45 female connection(the basic 5e wall socket kind) and a short piece of cat5e cable it stops functioning. All I am sending through the cable is the Nrf24L01 connections, including 7.5v from a buck converter to power the rf module(through another voltage regulator).
I have checked continuity with a multimeter on every connection numerous times. The multimeter shows continuity from Arduino to rf module through the RJ45 connections and cat5e. The module powers up, voltage looks good, but connection does not establish. I take away the ethernet and connect straight back into the Dupont wires and its back to working perfectly again.
This has led me to assume the culprit must be the RJ45 connections. Is there anyone with knowledge or experience with these parts that might be able to shed a little light on this for me? I am assuming that the wire inside a cat5e cable is more than capable of handling this not tremendous load. Am I incorrect about that? Is the cat5 cable also an issue?
Any thoughts or guidance would be greatly appreciated.
Thank you,
Aaron
First, the CAT5 is more than capable of doing what you have designed. I have had CAT5 cable between my ham radio and the tower mounted preamplifiers for more than 5 years without problem. They do not use connectors!
The only connector problem I have encountered was a cable made by my plant manager for me. A wire is crossed somewhere.
SO, did you use the correct crimping tool? Did you follow EXACTLY the color code for a direct connection and NOT for a swapped end connection. The color coded wire MUST be in the correct connector slots before crimping.
Thank you for the reply Paul.
I'm glad to hear confirmation that wire inside cat5 is plenty capable. I'm not doing any crimping. The Female RJ45 connection is the slotted push down type, and I am using a factory cat5 cable cut on one end. I have tried two different cat5 cables also. On the cut end I am connecting directly to the same Dupont wires.
I am using continuity on a multimeter to verify that I have all the connections correct.
This issue is the same if it is powered via usb. Also the same if power supplied is 5v to 5v pin. Also the same if nano is replaced with an uno. And also the same CE and CSN pins are assigned to pins 9 and 10.
Just to reiterate, each individual connection shows good continuity through the ethernet connections, but the RF module is unable to make a connection.
White-Orange
Orange
White Green
Blue
White Blue
Green
White Brown
Brown
These are TWISTED PAIRS, they're designed for BALANCED signals. If you drive each half of a pair separately its NOT going to work. You can run DC without issues, but hot signals need to be differential.
Thank you very much for the first helpful response!
I am testing from board to board. Pin13 has continuity with sck pin, pin12 with Miso, pin11 with Mosi, pin8 with CSN, and pin7 with CE.
Is the order you listed in reference to a crimping layout?
Is there a way to pair up the SPI connections such that they are balanced pairs? Is there an arrangement of SCK, MISO, MOSI, CE, CSN, +5v, and -5v that could work? I am planning on using the 8th wire for a video feed from an FPV camera. Is there a way to make balanced pairs with all these signals in a single cat5 cable? Or have I gravely misunderstood the function of the wires inside cat5?
Each color set is a pair, ORANGE, GREEN, BLUE, BROWN. You need a differential driver circuit to make it work for any pair. The MISO/MOSI each are a pair as would be the SCK, adding Vcc & gnd on the 4th pair means you need a 2nd cable for CE and anything else.
Google "differential line drivers" and use them (and matching receivers) to drive each PAIR.
You COULD just buy the right type of cable instead of adding circuitry and complexity.
Color order is RJ-45/TIA-568B standard. Your purchased cable is pinned this way if you look close, pins up, wire to left.
Live video wants RG-58U et al. coax cable, NOT twisted pair or even straight wire. TV is RF and needs shielding to prevent it radiating instead of conducting.
The 22 ga in the CAT-5 won't carry a lot of current without loss.