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 is the difference between a multiplexed bus and a multi-master bus

The jargon of terms in bus architecture literature is half the difficulty in understanding it. At some places the term 'multiplexed' bus is used while at some other places 'multi-master' bus is used. ...
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57 views

Bus mastering VS Bus arbitration [on hold]

If there are multiple bus masters possible in a bus architecture then is it certain that 'Bus arbitration' will take place before a master gets hold of the bus control or is it possible that bus ...
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81 views

Is there a direct to PCB punchdown Ethernet connector?

I’m attempting to design a small board that splits 802.3af and provides both data and 5v power to an MCU on the same board. I can find plenty of ICs with reference schematics for the splitter part - ...
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Lack of 'determinism' in Ethernet bus

While reading this website, I found out tha there is lack of 'determinism' in the Ethernet network bus as compared to some other buses like 1553. What I understand is that Ethernet is a single master ...
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Why is Bob Smith termination for Ethernet recommended if it's wrong?

I came across this article today (more detailed paper), which claims that the widely recommended Bob Smith termination (75-ohm resistor + 1000pF to chassis GND) may not be ideal (or correct). If this ...
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90 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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Why is an Ethernet cable not grounded?

There is no dedicated GND in the classical Ethernet 8P8C ("RJ45") pinout.[1] Why does the Ethernet spec not include a ground, unlike many other cable types used for interconnecting devices that may ...
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41 views

What is the maximum voltage and current for Data Signal in RJ45?

I am using a POE switch 1000Mbs to power a Blackfly camera. I know that each Ethernet port sends 48V to camera. What is the max voltage and current through the data cable. Or would the data signal (...
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57 views

What is the purpose of the T-568 ethernet color code standard

A question came into mind. as i was crimping some ethernet cables at home. I am talking about straight cable not crossover cables. What is the true reason for the T-568A or T-568B color standard. ...
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Which RJ45 pins should I use for power supply?

I'm somewhere in a process of creating mini automation system for hobby use. I've already put CAT 5e cables with RJ-45 connectors in walls. They are somewhere between 5 - 30 meters long. On one side ...
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1answer
45 views

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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88 views

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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58 views

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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1answer
169 views

Correct Ethernet Jack + Magnetics for 100Base-TX

I've been shopping around for Ethernet jacks for use in a personal project. The part specifically states that it's internal PHYs are 100BASE-TX/10BASE-T/Te IEEE 802.3 I understand the basic ...
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1answer
59 views

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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162 views

Detect activity on RJ45

I would like to make a circuit that allows to detect activity on a RJ45 cable (on which Ethernet would be used). When the cable is only connected to a single computer, link test pusles are emitted. ...
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1answer
213 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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44 views

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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210 views

How does “bidirectional” transmission on gigabit ethernet work 2?

I was looking for an answer to the question how the 1000BASE-T transmission works and I came up with this post How does "bidirectional" transmission on gigabit ethernet work? but still a few ...
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How important is the shield on an RJ45 connector?

If I am going to use a PCB mount RJ45 connector for 100mbps Ethernet, does it need to be a shielded connector, or can I get away with using an unshielded one? Is there some standard which deals with ...
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1answer
27 views

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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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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1answer
2k views

stm32f207 ethernet interrupts problem

I installed RTX (rtos from Keil) and Ethernet library from STM for stm32f207 MC. I configured UDP using ethernet + LwIP as in examples from STM. Without RTOS UDP works fine. I send and get packets ...
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1answer
138 views

How to get ip address Schneider PLC controller TM218LDAE40DRPHN? [closed]

I am new to PLC technology and I am doing the following step, listed below: Connect from PLC to retrieve data through Ethernet using Modbus TCP/IP. I found that PLC didn't have its IP address ...
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524 views

Ethernet ground multilayer pcb

I'm currently re-designing a 12-layer pcb. The only thing I am still struggling with is the routing of the ethernet. The layer stackup is as follows: Top Layer GND_1 MidLayer_1 PWR_1 MidLayer_2 ...
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1answer
43 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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41 views

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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1answer
299 views

Embedded Ethernet Solution w/ PoE+; SPI or MII?

I am currently undertaking my first hardware design attempt of an embedded Ethernet project w/ PoE+. I have experience working with embedded systems with Ethernet (mostly ARM M3/M4 processors with ...
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1answer
73 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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28 views

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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1answer
136 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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3k views

PC start button effect from electrical point of view

What I basically want to do is to connect one of the digital pins of a network-attached Raspberry PI to (one of) the connectors of the PC Power On button, so that when I issue a command coming on the ...
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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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1answer
40 views

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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53 views

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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1answer
346 views

Should I terminate the MII/RMII interfaces?

For Ethernet PHY design, the MDI interface should be terminated. Then how about the MII/RMII or GMII/RGMII interfaces? I've seen some designs terminated them, and most not. There are some PHY chips ...
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4answers
111 views

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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1answer
58 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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1answer
141 views

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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67 views

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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1answer
42 views

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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1answer
36 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 ethernet interfacing with PIC18F4520 help needed

I am a newbie to ethernet controller. I need to use ethernet controller to send sensor data to our server using http get method. I went through ENC28j60 documentation and microchip's TCP/IP stack as ...
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912 views

Connecting TVS before or behind Ethernet transformer?

I looked at several designs and recomendations. Why do TVS diodes sometimes connect before and behind transformer? What are the pros and cons of connecting before or behind?
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27 views

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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395 views

SGMII, MDIO and link training

I am reading this document : https://www.nxp.com/webapp/Download?colCode=AN3869 I got this link from NXP support, but I did not get a precise answer to my questiosn and I would like to be sure : The ...
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1answer
735 views

How can I configure PHY in cubeMX on own board?

I made a customboard using STM32f217VET microcontroller and KSZ8081 PHY (builtin pull-up resistors for TXP TXM and RXP RXM). I Configured my board to use MII mode, anda I used a 25MHz oscillator to do ...
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1answer
3k views

Picotux alternatives available? [closed]

I wanted to use a tiny Linux computer to read data from I²C bus. I knew there was Picotux, and I was thingking about buying one. But the website is down, so I guess there's no Picotux anymore. :( ...
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1answer
102 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 ...