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 does a router do? [migrated]

This question in its current state may be too broad, so I'll clarify. Obviously, most routers today are a combination modem, WiFi transceiver and router, taking the signal off the phone line, ...
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2answers
164 views

Passive POE: Need 5V @ 2A at the destination

Having a bit of trouble finding the right information on google, and I'm worried I might fry some cables so I thought it best to ask some far more knowledgable than myself. I want to connect 2 or ...
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27 views

Arduino Ethernet shield

I have some problem with Arduino and Ethernet shield. I have a small project with Arduino. Sensors send data to webserver. Everything works fine when arduino getting power from PC usb but when i give ...
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1answer
50 views

Ethernet Magnetic coil ground

In Ethernet Magnetic part why we using chassis ground and separated choke primary side form common ground?
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33 views

Receiving sensor data with Arduino: push or pull?

Every second I am reading a data string (comma-separated) from a battery management system via RS232. The first step was stripping the field name from the value; at times resulting in skipping a ...
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51 views

FPGA- ETHERNET-VHDL [closed]

I have a PCI card.The card contains SRAM and Ethernet Interface. I need to send my data from SRAM to client PC through Ethernet. I have to write vhdl code for SRAM and ethernet interface. but i ...
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1answer
54 views

What should be the size/package of Bob Smith Termination resistor?

We have run into a layout issue where the size/package of the 75R resistor used for Bob Smith termination on unused Ethernet pins is in question. The current package of this resistor is 1206 and we ...
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0answers
21 views

Data hub setup for a structured wiring panel [migrated]

I have a structure wiring panel in my home and the bedrooms and living room all have ethernet jacks. All the coaxial cables in the panel are labelled as: 1, 2, 3, fp1, fp2, and 2 cables called emarc ...
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1answer
53 views

Calculating attenuation of coax cable run

This question is related to my question about long-distance Ethernet. I discovered the Netsys NH-310C, a reasonably-priced device for converting Ethernet to coax for long-distance runs. The ...
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1answer
168 views

How a modem really works? [closed]

I really searched a lot and couldn't find a detailed answer(s), what happens when the Network Interface Card sends a Ethernet frame to the modem? Does the frame directly go inside modem's cpu or ...
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3answers
98 views

Designing an ethernet isolator

I'm trying to galvanically isolate a device which is controlled by ethernet (1000base t) via computer. I've been looking and apparently the ethernet standard provides some isolation, but after I ...
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1answer
36 views

How to design PoE splitter for Mode A and B

I would like to power my device via PoE, but I do not know which mode (A or B) is provided by the 802.3af power sourcing equipment (PSE). How should I design a splitter to accept both implementations: ...
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2answers
64 views

How to get up to 24 I/O pins from the PIC4550

Im trying to implement and understand the CRC by making a circuit, by using 1 byte (8 bits), and a highest power of the polynomial of four, these 2 values should be XORed until i get a final output, ...
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2answers
45 views

Vcc pin of TVS diode array

Bourns has various TVS diodes to protect Ethernet ports. Most of them (for example CD143A-SR05) have GND, VCC and I/O pins. I/O pins are for Ethernet signal line. Why do these TVS diodes have VCC pin? ...
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1answer
54 views

How to test Ethernet PHY's MDI interface through JTAG Boundary scan

We now use SCANWORKS Boundary Scan Tool from ASSET to make Ethernet SWITCH's manufacturing test. But in almost all PHY chips from broadcom corp, the MDI interfaces are "Linkage" bits. It means that ...
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1answer
35 views

Trying to control ethernet port in a raw fashion

I am trying to simulate JCHT35 switch to control a single actuator. There are 3 wires with an RJ45 tip plugged into the blackbox j45 female port connected to an actuator inside. What I am trying to ...
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1answer
41 views

Ethernet Signals Complementary

I'm doing a little project, regarding a ethernet to fo converter but I have some doubts. The problem is how TX+ and TX- behaves, are those complementary? I mean if TX+ is high than TX- is low. My ...
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2answers
72 views

FCS verification of ethernet frame

i am trying to transmit a Ethernet frame from fpga to pc. my udp frame is: ...
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0answers
52 views

Ethernet PHY Device read and write operation is not working

I am trying to Read and write the DM9161A PHY MII-register through EMAC ATSAM3x8e. ...
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3answers
2k views

Can the fake USB flash drive attack happen over Ethernet?

You may have seen the article This USB Drive Can Nuke A Computer where it shows how a flash drive shaped device can completely fry out all the components of a computer. This is very shocking (pun ...
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0answers
70 views

POE external Magnetics Alternative to magnetic RJ45 jack ieee803af

I can't use a magnetic jack for this POE PD (ieee803af), because we use another connector (M12). Looking for components to replace the internal magnetics, I found that almost all components and ...
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2answers
101 views

USB to Ethernet broadcaster

I have an industrial breathalysers that outputs its status via a USB 2.0 OTG port. What might be a suitable combination of processor and perhaps Ethernet chipset. I have not played with the modern ...
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1answer
88 views

Oscillator and output load

For the Ethernet application in my design using RMII interface, I need to drive two CMOS loads (two reference clock pins, one of a Freescale Kinetis K60 Microcontroller and one of a TI's PHY chip) ...
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1answer
43 views

Simulate modems and leased line over ethernet

I am using a leased line with two modems on the edges. Those modems receive x.21 protocol from db25 connector on their back and transmit to each other over the leased line. For some pairs of leased ...
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0answers
57 views

Problem in communication between STM32F429 with Ethernet PHY

I have problem in communication between STM32F429 with Ethernet PHY. I have Emcraft SOM(system on module) board, STM32F429 and Micrel Ethernet PHY IC interfaced or connected on SOM Board. I have taken ...
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0answers
38 views

What is the purpose of the statistics register present in the EMAC of the DMA in ATMELSAM3x8e controller?

At present, I am working on interfacing the EMAC module with my SAM3x - Taiji Uino board for high speed communication. When I was scanning through the internal structure of the EMAC,I came across this ...
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1answer
120 views

Impedance matching components with Ethernet

I’m designing a small switching circuit for 1000Base-T Ethernet and have a concern regarding impedance. The board design consists of 3 shielded Ethernet jacks and 4 DPDT relays (here) made for high ...
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2answers
349 views

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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2answers
94 views

Ethernet Port Listener Throughput Maximisation

We have a distributed sensor network (12 nodes), using Ethernet as the backend protocol. These are networked at 100Mb/s to a single 1Gb/s link using a 16-port switch. I've previously seen Java and C ...
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1answer
269 views

Can I generate a 90° Clock signal with Xilinx's ODELAY for RGMII?

Some time ago I implemented a GMII interface for my Gigabit Ethernet core. Now I'm trying to do the same with the RGMII protocol. The reference implementation from Xilinx uses IDELAY[|E1|E2] ...
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2answers
168 views

Why are ethernet ports always upside-down?

I have noticed that in almost every board, RJ-45 Ethernet sockets are always soldered upside-down. Why are these sockets made this way? Wouldn't it be easier to make and solder them with the pins ...
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1answer
62 views

Does SGMII contain MDIO?

When connecting a NIC (Intel I210-IS) to an gigabit ethernet switch with integrated PHYs (Marvell 88E6176) using the SGMII interface, I came across the following question: Since SGMII is a serialized ...
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1answer
143 views

Purpose of the magnetics center tap in Ethernet [duplicate]

What how the magnetics center tap work in Ethernet HW configuration? I've read that it depends on the specification of the attached PHY, sometimes must be connected to the PHY's DC supply, but i can't ...
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1answer
63 views

Switching between two Ethernet magnetics and one simple Phy

I'm deep into a project and I would like to ask how can I switch 2 ethernet interfaces to single PHY. I know that there're some suitable analog switches for this purpose like MAX4890, but I don't ...
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2answers
67 views

Extend an rj45 Jack

I want to extend the Ethernet port (of my raspberry pi) using a short bit of cable plugges in into the Ethernet Port and solider to another rj45-jack. In the jack I have here, are some built-in coils ...
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1answer
127 views

High speed data from microcontrollers to pc using daisy chain

I have STM32F4 discovery boards. I have 30 such boards supporting maximum data of 128Mbps. The max data at any instance in complete system would be 300Mbps.I need to pick this data and send it to PC. ...
14
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4answers
2k views

Are solder bridges on chips always bad?

I just bought my Arduino Ethernet shield – a knock-off one for $10 instead of $60. I connected it up, but it doesn’t work – LEDs light up but do not blink, and no ethernet link is established ...
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4answers
189 views

2000-feet Ethernet connection for Internet and other data

I am building a house. It's located about 2000 feet away from the nearest Internet cable. I had to run our electrical service underground the whole way, and have already installed a conduit for ...
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0answers
66 views

communicating between computer and the board which has a microcontroller

I have a PC and Ethernet module(ENC28J60). I want to connect each other using socket and send data from PC to the Ethernet module. physically both r connected through LAN. I want to make my PC as the ...
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1answer
103 views

How to program enc28j60??

I read enc28j60 is unprogrammable directly from the computer but it has registers that I can program so how can I excactly do this.. is it programmed from the mcu connected to it through spi or is ...
3
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1answer
69 views

Ethernet components location

The normal ethernet components configuration: MAC <-> PHY <-> Magnetics <-> RJ45. My RJ45 connector must be mounted on the system box's front panel, so there must be a wire routed from the ...
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1answer
64 views

Pressure Sensor Calibration

Here's the situation: I need to verify the pressure sensor accuracy of a control board. I have a software to verify the pressure and I am using Ethernet Communication to communicate between my control ...
4
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1answer
412 views

Caculating baud rate of Ethernet per wire

I'm trying to find the answer to what should be a simple question. How do I calculate the physical rate bits are transmitted on an individual Ethernet wire? I am interested specifically in 100 Mbps ...
2
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1answer
302 views

Can an RMII phy be connected directly to another RMII phy

I have some Microchip (SMSC) LAN9303 Ethernet switches in my system. The LAN9303 is a 3-port switch which has 2 connections for twisted pair cables and one MII connection. The switch chips are some ...
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1answer
231 views

choosing diodes for a passive ethernet hub

I found several guidelines for building a passive ethernet hub, mostly quoting this. The guide specifies which diodes to use, but I cannot find them anywhere. What are the parameters I should search ...
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3answers
172 views

Is it possible to check an Ethernet twisted pair with a multimeter?

It would be useful to measure electrical parameters (such as I,U,R and perhaps L,C or other) at the end of the cable, when the other end is disconnected or connected, and analyze the physical layer of ...
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2answers
27 views

How is the capacity of link more for single network link

In networks capacity_of_link = bandwidth*propagation_delay My doubt is how can a same wire carry multiple signals? Is is because the wire is very long (still the wire can be either high or low). I ...
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111 views

Can a CAN bus support power over ethernet?

I'd like to reduce my loom for a battery box. Every time I run a line i.e. CAN or low voltage power, it has to be isolated from the master controller which communicates with each slave. I'd like to ...
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0answers
29 views

Arduino with Ethernet Shield Problem With External Power Supply [duplicate]

I asked this question at Arduino forum but nobody answered. In fact, my question seems familiar but there is a little trick. I use Arduino Mega with Ethernet shields (And also with screw shield) and ...
3
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2answers
136 views

Why do serpentine traces (supposedly) entail decreased ESD immunity?

In an Intel guideline for their 82579 Gigabit Ethernet controller I've read (p. 18) that a side effect of using serpentine traces on the MDI (which carries the actual Ethernet signals) leads to ...