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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LAN9512 USB hub and Ethernet Controller Problems

I'm working on a custom board using a Raspberry Pi computer on module (COM) (info and schematics here: http://www.raspberrypi.org/raspberry-pi-compute-module-new-product/. The board is based on the ...
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51 views

How to take Arduino to PCB [on hold]

Note: I don't have much electrical engineering experience when it comes to designing a PCB. I have created an Arduino project that I think can be commercialised and I understand how to convert the ...
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2answers
55 views

What purpose do transformers have in electrical interfaces such as ethernet? [duplicate]

Some electrical interfaces, such as ethernet, specify that the outward-facing socket are to be isolated by a transformer. For instance, see this circuit example from the data sheet of an ethernet ...
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45 views

CAT5/6 to non RJ45 connector assemblies

What types of non-RJ45 cable assemblies plugs/sockets are common? I need to carry instrumentation signals (8 of them) which are a mix of small signal and 60Vpp. I cannot use RJ45 in case someone ...
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37 views

Implementing and debugging LwIP

How should I start working with LwIP stack? I've STM32F429 processor with LAN8720AI on board and my task is to program simple project which will show ethernet working properly. I tried to configure ...
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1answer
51 views

FIFO in ethernet module

In Ethernet module , why do we need FIFO block before the mac layer ? Can we bypass it ? Thanx in advance
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2answers
181 views

Why does Ethernet on UTP have much greater range than other modern protocols?

OCuLink, SATA, USB 3, and Displayport all provide on the order of a few Gbps per signaling pair, and are limited to a cable length of just a couple meters. Ethernet via comparable cabling provides ...
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1answer
35 views

Do I need to cross my Tx and Rx for an Ethernet AUI interface device?

I have one device with an AUI Ethernet interface coming out of a non-standard connector. I'm making a cable to attach the device to a COTS transceiver which contains the standard D-Type AUI connector. ...
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1answer
44 views

which devices on network use CSMA/CD

CSMA/CD 's definition based on wikipedia is : Carrier Sense Multiple Access With Collision Detection (CSMA/CD) is a media access control method used most notably in local area networking using ...
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43 views

Ethernet pass through connector on bottom of IP phone. What do you reckon is inside?

I was hooking up some 10/100BaseT Ethernet cables at a customer site and I noticed that the Voice Over IP phone on a desk had an Ethernet input and an additional RJ45 that serves as a pass-through ...
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1answer
112 views

Bob Smith Termination with POE

I'm looking into doing a Bob Smith termination for a Power over Ethernet (POE) PSE. The TI app note shows the following termination: But all of TI's reference designs (and later figures in the same ...
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2answers
84 views

Why does a Category 5 rated jack have different solder tail positions than a traditional jack?

I am attempting to specify a replacement part for a modular jack used in an original design (I basically need something that will stick out farther than the original). However, the part I would like ...
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101 views

Ethernet: are Tx and Rx reversed in this schematic? What are the consequences?

On the Ethernet section of the schematic given for the BeagleBone Black (rev C) we see pins TXP and TXN of the LAN8710A PHY going to pins 3 and 6 of the component labeled LPJ0011BBNL (manufacturer: ...
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3answers
74 views

How does “bidirectional” transmission on gigabit ethernet work?

I was reading about the various twisted pair protocols, being distracted by the marvels of Wikipedia when I went to look up the way to wire a connector. And I'm wondering how it can transmit in both ...
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2answers
150 views

Does the voltage increase on 10Base2 and 10Base5 ethernet when the signal is reflected? Will this trigger the collision detection?

From what I understand, the collision detection will become true when the voltage on 10base2 or 10base5 coax is abnormal. Quote from Wikipedia: If termination is missing, or if there is a break in ...
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1answer
75 views

Ethernet UDP diode

I want to create a device of some sort where I am absolutely positive that only UDP traffic can pass one way. Of course I could setup whatever old router I might have, the thing is I want to make it ...
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0answers
27 views

Are there link pulses when autonegotiation on ethernet is off (force speed and duplex)?

I read this. Is it correct that there is no link pulse when speed and duplex are forced (autonegotiation turned off)?
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26 views

On bus Ethernet, how a connected station detect link connectivity?

On point to point Ethernet, link pulse is used between 2 connected devices to detect link connectivity. Reference On bus Ethernet, how a station connected to Ethernet bus detect link connectivity?
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1answer
179 views

Effects of impedance matching between 50 and 75 Ohm coaxial cables for 10 Mbit/s, Manchester-coded signals (20 MHz)

TL,DR: This is quite a bunch of text because I have included plenty of background info. However, there will finally be a good, and precise question: Should I use an impedance matching network when ...
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1answer
84 views

Current over CAT6 ethernet cable

How much current can a CAT6 cable reliably handle? I want to use 3 of the cores for +5V and 3 cores for GND. I'm wondering at what current I need to think of another power solution.
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84 views

Arduino won't connect to Internet

I recently bought an Arduino Ethernet shield which I want to use with my Arduino Duemilanove ATmega 328. I connected my ethernet shield with my Arduino board and connect shield with my router using ...
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1answer
49 views

Ethernet: Why is the link status “down” when there is a speed mismatch?

For any networking (ethernet) equipment, the link status (layer 1) is down when there is a speed mismatch between two ethernet interfaces (say: one is 10 Mbit and another is 100 Mbit). Is it ...
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65 views

Carrier Wave in Wired Data Networks

I know this must be trivial for many... Which are the main reasons why line data is not modulated/demodulated in normal enterprise wired networks (in the sense that discrete voltage levels are used)? ...
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1answer
1k views

Why is Ethernet not intrinsically safe?

I understand from a training session that ProfiBUS is considered intrinsically safe, while ProfiNET is not. Some googling indicates that ProfiNET can never be intrinsically safe, because Ethernet can ...
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3answers
187 views

Maximum cable length for 5V or 3.3V I2C, UART, or 1-wire signals over Ethernet and how to increase it?

I know similar questions have been asked before (Maximum cable length for 3.3V UART signals) but I would like to know the answer more specifically for a hobbyist. I've been experimenting connecting ...
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1answer
83 views

Ethernet NIC architecture: Function of loopback circuit

I want to make sure my understanding of the function/the needs of loopback to detect collision is correct. There is frame to transmit from Ethernet controller. TX transmits to wire, loopback and ...
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2answers
80 views

Virtex 6 ethernet

I have tried to implement the example design which provided with "Virtex 6 Embedded Tri-mode Ethernet MAC wrapper v2.3" in Core generator,on virtex 6 development board(ML605) When I program it on the ...
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0answers
75 views

How to get Ethernet cable into a small enclosure

I have a project with a Raspberry Pi in a small enclosure that is in a weather-protected outdoor location. I currently have power and gpio signal cables entering the enclosure through grommeted ...
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0answers
71 views

VGA to Ethernet [closed]

I am using VGA to Ethernet Frame grabbers for my job. I need a VGA to Ethernet frame grabber which is like the Epiphan's product on the internet(it can be easily found when searched in the internet). ...
3
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2answers
303 views

Cat5 wire connector does not appear to be continuous

I'm trying to use a cat5 network cable and connection jack (what I'm calling the female version of cat5) as a way to quickly connect/disconnect 8 wires for an electrical project. I bought a few cat5 ...
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0answers
63 views

Ethernet communication [closed]

I want to make a simple program which achieves Ethernet communication. Specially I will try to connect this ENC28J60 Ethernet LAN Network Module and make a simple real time monitoring application ...
2
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1answer
129 views

Is it possible to inject USB signals (with power) through Ethernet?

I'm just curious whether it is possible to inject USB through Ethernet in a way like POE does but with the additional data lines USB needs. As per my understanding Ethernet (at least the slower ...
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0answers
39 views

Link integrity test pulse vs carrier signal

Ethernet uses a refinement of ALOHA, known as Carrier Sense Multiple Access (CSMA), which improves performance when there is a higher medium utilisation. When a NIC has data to transmit, the NIC ...
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0answers
244 views

How to get an ENC28J60 to work?

For starters: Yes I know I'm about to reinvent the wheel with the following task ahead. I want to create my own library for the ENC28J60 for an AVR (ATMEGA1284P). So I've been browsing the net for ...
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90 views

Converting Ethernet hardwire signals to Wifi using RMII interface and embedded bridge module

I have an embedded sensor that has an Ethernet RJ45 cable/connector, which include Tx+, Tx-, Rx+, and Rx- signals that I need to convert to wireless. I need to embed it with the sensor and it needs ...
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1answer
45 views

What is 'valid signal' that router receives to indicate physical status is 'up'?

If the Ethernet interface has a cable connected and is receiving a valid signal, the physical link shows an “up” status and there are no active alarms or defects. If the interface is not connected ...
2
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1answer
135 views

RMII MAC side routing and signal integrity

I have some signal integrity and EMC questions. In my board LPC1768 RMII interface is connected to LAN8720. Because of pin locations some RMII signals must go through bottom layer. This is a four ...
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2answers
111 views

What is “M” in Hartley's law?

If Hartley's law is: $$ C = 2 B \log_2 M $$ I know this equation is part of calculating the capacity of a channel. I also understand that: \$C\$ is the digital bandwidth, in bits/second \$B\$ is ...
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64 views

Connect two embedded devices with USB host with Ethernet?

I need to connect two microprocessors that only have USB host, not OTG or client. Obviously I would like to connect them as directly and quickly (ie 10's of Mbit up to 100) as possible. A USB to ...
4
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3answers
137 views

Can a barrel shifter be done combinatorially?

I was told that 66b/64b encoding in 10Gb Ethernet (10GBASE-R) requires a one-cycle barrel stage, which adds a necessary one cycle to the theoretical terminal latency. The Wikipedia page on barrel ...
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2answers
159 views

What happens if I accidentally connect an Ethernet device to my 1-wire bus?

I have built a networked temperature sensor by connecting several DS18B20 temperature sensors to my Arduino. I've tried to visualize the setup with this schematic (sorry if this doesn't make any ...
4
votes
2answers
114 views

Two analog power planes for same voltage

I'm designing a board with LAN8720 and LPC1768. LPC's ADC and LAN's magnetics connections require analog 3.3V power. Should I separate these two analog power planes with a ferrite as I separate it ...
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0answers
45 views

Reading Ethernet Link Pulse

I want to read the link pulse of an ethernet connection (connected to hub one end and unconnected on the other) through an oscilliscope. Eventually I want to detect the pulse using a microcontroller ...
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2answers
157 views

Unmanaged Ethernet switch silicon? [closed]

I need to add an unmanaged Ethernet switch circuit to my PCB, but I can't find any usable silicon, not even with 100BaseT. Am I missing something? I don't want to have to connect it to a ...
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2answers
104 views

Ethernet signals

I have an end of an ethernet cable but I don't know where it goes. I want to see if it is connected to a device at the other end. Looking at the pinout you have a TX+/TX- and an RX+/RX- pair of ...
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0answers
79 views

Ground Plane, Bypass Capacitors and Differential Pairs

I've placed a KSZ9031MNX Ethernet PHY on my board, and am now trying to get power routed to it. The digital side will merely be annoying to do, I think, but I'm at a complete loss on the analog side. ...
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1answer
96 views

Collision detection on ethernet coaxial cable

On ethernet coaxial cable, how collision is detected by the sending device? I was told by someone that it is related to high electrical current and the difference between the sent frame and the ...
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0answers
144 views

Read and write FPGA registers via USB or Ethernet

I'm working on an FPGA project on an Atlys Spartan 6 board. I'm programming it in VHDL. I have two 32 bit registers, one for output, the other for input. I need to be able to, respectively, read and ...
2
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1answer
221 views

AVR Embedded Webserver + Time

I have the task of implementing an embedded webserver (using ATMega328). Broadly, the system would provide the following functionality Allow user to change system parameters using the web interface ...
0
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1answer
62 views

L2 Bridge over Asynchronous Serial line [closed]

I am using pppd (in linux) to send ethernet data over a serial line to another computer. How can I preserve L2 headers while sending Ethernet frames over serial line? It seems the ppp protocol sends ...