Questions tagged [ethernet]

Questions about the electrical implementation of Ethernet; ask another Stack Exchange for software or protocol questions. Specify the speed as 10/100BASE-T is somewhat different from 1000BASE-T, apart form the speed. Those are copper standards; Ethernet over fiber optical cable is also defined.

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what's the difference between lan8720 and ks8721 [on hold]

I'm fairly new to ethernet protocol . I want to choose between lan8720 and ks8721bl for my products. since lan8720 is much cheaper I thought there may be a huge difference between them but when I ...
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Bob Smith termination for Ethernet magnetics

I know that Bob Smith termination is recommended for Ethernet differential pairs. Please refer the below image for Bob Smith termination resistor placement. As far as I know, Bob Smith terminations ...
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Dielectric (HI-Pot Test) Failure on Ethernet Port

We have failure on Dielectric test between Power wire to Ethernet Port. Failure was observed near 1.7kV. After test Ethernet port was damaged (Phy chip). See attached Case 1 :- Where we apply High ...
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Cat6 Ethernet connections

I have been trying to create my own CAT6 cable lengths, but have been having problems with achieving a connection. Every diagram that I have seen online doesn't match my wires exactly. I have an ...
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Should Ethernet MDI Pairs all be Length Matched (Inter-Pair) before going into magnetics?

I've been trying to find information for the above question and I can't seem to find anything. I have 1000 BASE-T lines coming from an Ethernet cable to a PCB mounted connector. I'm pretty much ...
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210 views

How are 200 GBit/s over twin-axial copper cable achieved?

The 200GBASE-CR4 standard [1] defines ethernet communication with 200 GBit/s using four lanes and PAM4 modulation over a maximum distance of 3 m. A single PAM4 symbol encodes two bits, therefore, I ...
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Hardware testing for Ethernet

What are the hardware tests for Ethernet? Just need to verify the MII/RMII timing waveform with respect to specifications given in the datasheet.
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GbE Phy(88E1543) with POE+ PSE(LTC4266) design (POE+ magnetics? RJ45 with Integrated magnetics?)

I'm trying to understand how i can inject power to a 4 bank RJ45. I want to use these parts : - LTC 4266 4 ports PSE (802.3 at compliant for GbE, in type1 class3 for 13W at each port) - Marvell ...
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42 views

Thin CAT6 cable - RFI problems?

I have got a short length (1m) of standard fat CAT5 shielded cable that runs inside a piece of equipment before the signal exits via a bulkhead connector to a PC. It's the old kind that is a real pain ...
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136 views

how can homeplug device send ethernet down mains wiring

AFAIK when you wire a patch cable out of 5e, you only need to wire two of the conductors correctly for it to function as a ethernet cablebut you won't get gigabit ethernet. However Homeplug uses ...
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stm32F401re ethernet shield unable to associate IP address

I bought STM32 F401RE and Ethernet shield HR911105A with MCU W5100. I'm not able to configure simple connectivity with it. I have setup all SPI wires and simple code for setting up IP, subnet, and ...
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59 views

which interface to use TBI, GMII or MII? (FPGA)

I am working with the SoC FPGA Smartfusion2 M2S010-MKR-KIT. It is intended to exchange some data between the SoC and the PC. For that reason, I aim to use Ethernet. As far as I understood, in order ...
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Ethernet trace layout and passive placement

I'm designing a board (with KiCAD 5.1.0) besides other I need to properly route two ethernet ports and the whole board should be kept as small as possible (50x82mm). The guidelines of components (...
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62 views

Special requirements 100Mbps (Ethernet) connection to PCB

Is there any special requirements/limitations to how 100Mbps Ethernet conductors can be connected to the PCB? For instance in the design prompting the question I have a Ethernet connection entering ...
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What is the maximum routing distance between MAC to PHY recommended?

Picture to Keep the Terminology Clear I am in the plan of using ETH for inter processor communication I need few ETH lanes to be shared between boards, i wish to avoid ETH PHY and magnetics as the ...
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PHY Link only establishing 10 Mbps speed when both devices 100 Mbps capable

I've designed a circuit board with a Microchip switch (KSZ9897) going to a Ethernet-to-VDSL module (LX200V20). The PHY ports between the two devices are connected using a transformerless connection ...
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56 views

Why this evaluation board use different track impedance than the right one? Ethernet PHY, routing

Im doing a design with a implementation of 1Gb ethernet switch, for that I bought a evaluation board to do it well. The problem is that in the layout of the ev board I can check that the track ...
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IP Camera and USB data transmission over Ethernet Cable

Currently I am working on a project that requires connection of the Arduino and IP Camera over single Ethernet cable to a laptop and additionally supply power to a robot. The goal is to stream Video ...
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Can you replace a RJ45 connector with smaller connector?

I'm designing a small board that needs an ethernet connection. However, the RJ45 jack takes considerable space. I would like to reduce the footprint of the connector to safe some space. Would it be ...
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Add Ethernet Switch chip to project based on PIC18F97J60

We developed an Ethernet-connected device that uses the Microchip PIC18F97J60 controller. This particular PIC contains the PHY that allows us to simply connect the chip to Ethernet magnetics and then ...
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76 views

Single pair ethernet (SPE) PHY with ESP32

can I connect this Single Pair Ethernet PHY http://www.ti.com/product/DP83TC811R-Q1 to a ESP32 chip? Do I miss something? Does anyone already know a Switch for Single Pair Ethernet? Looking forward ...
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100BASE-TX (MLT-3) to 100BASE-FX (NRZ-I) conversion

Is there a way to convert 100BASE-TX packet to 100BASE-FX packet only by use of MLT-3 to NRZ-I coding scheme convertion by means of simple logic ICs such as some trigger ICs (wichout the use of FPGA ...
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How much mains leakage does an Ethernet connection to a PC induce, and what is the operating leakage path?

It seems that some users on another Stack have reported GFCI nuisance trips caused by mains leakage through twisted-pair Ethernet cables connected between computers on different branch circuits, or ...
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54 views

Structure of Pairs inside a Cat Cable

Is there a standard arrangement for the pairs inside a Cat7|6|5 Ethernet Cable? As shown in the picture, they are in the sequence Orange-Green-Brown-Blue, or the Orange Brown always as opposite pairs,...
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61 views

Ethernet connection using only one twisted pair

For my degree work, i make some reseaches for different bus systems and i've found ethernet a bit different than others: The old 10Base5 and 10Base2 ethernet used only one pair of conductor to ...
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how to confirm that PCB Ethernet layout does not affect perfornace

short version: - How to test if ethernet traces on PCB causing any distortions to the signal? - Is it possible to generate ethernet signals from a windows computer and measure them with an ...
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53 views

Gen3 LAN Bypass

I am working on LAN Bypass circuit for 1000 Mb/s Ethernet ports. I need to use relays to turn the bypass mode or no link mode on during power failure. My doubt is whether the relays should be used ...
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No connection between host PC and mbed via Ethernet

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Transmission distance rs485 vs ethernet

I have a question, why is rs485 limited to less than 100 meters at 10mpbs ( mbaud ) and is 100Base-TX ethernet applicable on 100 meters with 100 mbps bitrate i know that rs485 normally use a sort ...
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mbed OS 5 TCP Socket

I have a few question regarding mbed OS 5's new TCP API: Some background: I will have multiple mbeds linked via Ethernet to a PC. The PC, whose IP address is fixed and known by each mbed, initiates ...
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84 views

STM32F103 reset button does not work [closed]

I am working project, using STM32F103C8T6 and W5500 Ethernet module. My project is something like network relay. My problem is ...
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3answers
97 views

Power small microcontroller from motherboard RJ45 ethernet port

I'm wondering if it's possible to power a microcontroller (e.g. ATmega328) from a Ethernet RJ45 motherboard port. Unlike USB, there is no power line, all pins/lines seem to be data only. I am ...
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Ground planes disposition in Ethernet connection

I am designing a board that will have sensible analog signals and a processor communicating with the external word via Ethernet and I want to avoid that common mode currents couple into my analog ...
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What can happen if 24vdc is applied to an Ethernet port?

We have a device with two RJ45 ports. One of these ports is for receiving 24vdc on pins 7(-) and 8(+) to power the device. The other RJ45 port is an Ethernet connection. The ports are of course ...
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34 views

enc28j60 ordere wrong resistors

i prototype a small board with ENC28j60. Instead of 49.9 resistors I have ordered by mistake 47R ones, What do you think? will it work? It is only 10M ethernet
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{enc28j60} Is the 50ppm crystal good enough

I have some 25MHz 50ppm crystals but I am not sure if they are good enough to be used with ENC28J60.
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ENC28J60 - is this connection correct

Just wondering if this is correct. I never used to design anything using this chip.
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87 views

Design ethernet switch for multiple devices on pcb?

I'm working on a pcb design with a Raspberry Pi CM module and a microcontroller with ethernet capacity. The goal is to connect the devices to the internet. I'm currently using a normal ethernet ...
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1answer
100 views

Adding fiber optic ethernet to a circuit

I'm working on a project that involves transmitting data over very long distances (10-25km) where radio communication is unavailable, and I have been looking into the possibility of adding a fiber ...
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Media converter - Coax or Twisted Pair [duplicate]

I am working on a Double Leaf Bascule bridge spanning across a river that needs rehabilitated. The bridge is driven from a ControlLogix PLC consisting of 4 racks on the nearside span. Power/control is ...
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52 views

Cat 5e, any gauge?

I am working on a double leaf bascule bridge and installing a PLC I/O rack on the farside. The power transmission between the two piers (nearside and farside) is via a single submarine cable (...
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Why does 100G Ethernet use FEC while Infiniband doesn't?

The 100G Ethernet physical layer signalling is moving to PAM4 and using Forward Error Correction (FEC) when the lane signalling rate is greater than 25 Gigabaud (Either 4 lanes x 25 or 2 x 50). ...
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LAN8720A - Reset and Power-up Issues

I am developing a new board that uses an STM32F427 MCU and the LAN8720A as an ethernet PHY. This is my first design with this MCU, but I've done multiple designs with this PHY and other MCUs. I never ...
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Should I use shielded RJ45 plug by the computers? [closed]

If I have shielded cables, jacks and plugs and I ground the shielding properly, then should I use shielded plugs at the computer's site too? I mean if I do so, then the shielding will be connected to ...
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135 views

Gigabit detection DIY

Ethernet up to 100Mbps uses only 2 of the 4 twisted wires in an ethernet cable while gigabit is using all of them. Connecting an LED to one of the gigabit-only pairs should therefore make it easy to ...
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Do Broadcom's Ethernet chipsets need special software to operate?

I want to implement an Ethernet switch using Broadcom's chips. Are singing an NDA and getting the datasheets enough to work with the chips? I have heard that the chips must be programmed by a special ...
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105 views

Using only 2 pairs of Ethernet

I'm having a custom cable made that will only use 2 of the 4 pairs for Ethernet. I'm connecting a 10/100 Mbps device to a network with other GigE devices. Pinout is clear: However, I have seen one ...
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86 views

Regarding Current in CAT 5e cable [duplicate]

Can we supply 2A DC current at 5V in the pair of ethernet CAT 5e cable?
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Broadcom Ethernet PHY link-up issue

We are using BCM5482SA2KFBG PHY for ethernet link in SGMII mode by selecting INTSEL = 2'b10. The PHY was supposed to establish a link upon power up using Autonegotitation without any management ...
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how to implement Pic18f97j60 with PoE Ethernet

I am a beginner when it comes to mcu and electronics design, I did some projects on Arduino and other ready made microchip boards. However this is my first time building something from scratch. I ...