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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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Interrupt during packet transfer

I'm using the mbed TCP/IP Socket library to receive incoming messages via ethernet. Currently, the incoming data is read in an infinite while(1) loop (i.e. as fast as possible). I will also be ...
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2answers
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DP83848 + STM32 & Failed EMC (massive spikes of 25MHz crystal harmonics)

So we've failed EMC two times now because of spikes of 25 MHz harmonics from 175 MHz to 300 MHz, especially 175 MHz, 225 MHz and 275 MHz with peaks easily 30-40 dBuV above noise floor measured with ...
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51 views

Problem with PHY KSZ9031RNX

I am facing a serious problem with a design using the PHY KSZ9031 from Micrel. The same schematics are used for both versions of the same product. It is possible to use both speeds from 100Mbit up to ...
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2answers
48 views

Finding an Ethernet transformer when I have it's characteristics

I am using the Novatel OEM729 board for a project, and I need to implement Ethernet in the project. According to the Novatel OEM7 manual, page 48, the OEM729 does not have Ethernet magnetics, so I ...
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How does Ethernet to CAN conversion work?

I am wondering how an Ethernet-to-CAN converter works. CAN is a multi-master broadcasting network where messages are associated with IDs. Each message type has a unique ID. Devices listen to all ...
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ENC28J60 rejects unicast packets - unicast filter is on, MAC is set, and addresses match

I'm programming an ENC28J60 driver at the moment, and have encountered something odd when attempting to receive packets. More specifically, unicast packets. According to the datasheet, when the ...
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28 views

Cycle time with line->ring topology (industrial ethernet)

Firstly, I asked this question in Network Engineering, but @RonTrunk advised me, that here will be better. I have an interest in 3 standards: EtherCAT, SERCOS III, Profinet. How are changed their ...
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1answer
36 views

Power over ethernet and common-mode termination

I have a non-standard Power over Ethernet application (connector, and devices are not ethernet standard but we are using ethernet pairs and protocol for communications). On looking at PoE schematics I ...
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1answer
34 views

Proper connection of choke coil in ethernet magnetics

I need to use the medical ethernet magnetics by Pulse HXU6200NL (it is the only 2MOPP medical-certified PoE magnetics I can find). These are of the rather common transformer/choke coil topology. My ...
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2answers
96 views

Double ethernet magnetics for a passive medical application

I am designing medical data acquisition equipment that requires moderately fast data transfer. As part of the design we are using a custom 100BASE-T PoE architecture (and cabling) to the data ...
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1answer
73 views

How come this non-standard ethernet wiring works?

I am setting up ethernet in a friends house with cat 5 cabling. I do not do this professionally but I have made like 20 patch cables and installed about 20 wall sockets before in my own house. My ...
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1answer
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Designing an PCIe ethernet NIC with built in ethernet switch

I am trying to design a ethernet network card that will plug into a PCIe slot and have 2 etherenet ports visible to the user that are connected by a unmanaged layer 2 switch. My architecture ...
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KSZ8863MLL TXD2 problem

I have a Infineon XMC4500 cpu connected to a KSZ8863MLL (two port Ethernet switch) operating in MII mode. We built some Boards - arround 50 are working but now im facing an isssue. The board that ...
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73 views

Long distance internet connections

My friends and I are PC enthusiasts and we are making a NAS, unfortunately we live in a suburb of Melbourne, Australia and internet here is garbage (lower than 8 megabits most of the time) so this is ...
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4answers
1k views

CAT5 for telephony

I wish to extend my incoming telephone connection using CAT5 as I've heard it could provide better performance than standard single stranded telephone wire over long distances. There are only two ...
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1answer
97 views

Ethernet controller not recognized on PCIe bus

I designed a carrier board for this SOM: https://wiki.solid-run.com/doku.php?id=products:ibx:documents As I need a second Ethernet port I added an Intel I217 Ethernet controller. Unfortunately it ...
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0answers
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Cable Side and Physical Side of a PoE Magnetics

I am reading the datasheet of PoE Magnetics. I am not able to understand which side belongs to cable side and which belongs to ...
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2answers
119 views

Ethernet switch with 8 ports and PTP [closed]

Hello) I need a solution for a board with 8 100/10 ethernet ports (with copper/fiber switching capabilities, PTP and idealy also with PRP, HSR protocol capabilities). I've found KSZ8999I switch, but I ...
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POE Voltage Reducer

I am trying to build an inline POE voltage reducer, one that will take a 48V input to power a 24V POE device (only draws 10W). Pulse makes some RJ45 jacks with integrated magnetics. Combined with a ...
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1answer
51 views

Should I model an ethernet message decoder with byte based instead of bit?

The steaming interface (for example the Avalon ST) input logic data[255:0] in_data; // a 256 bits input stream data The local signals of data like this: ...
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2answers
149 views

Using SFP modules from a microcontroller

I'm interested in having an embedded device send data optically. This is for test and measurement, where having conductive cables is problematic since it will perturb the measurement. The device is ...
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1answer
149 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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54 views

HR911105A connector problem!

I have a stm32f407 microcontroller and I want to use ethernet with DP83848 physical layer. Finally I have HR911105A and when I pluged in and program the microcontroller, when I want to ping, it did ...
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2answers
143 views

Impedance Matching Resistors on MII Ethernet Lines

Microchip is taking forever to activate my account so I will ask this here... I am using the KSZ8081 PHY for MII Ethernet. https://www.mouser.com/ProductDetail/Microchip-Technology-Micrel/...
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2answers
97 views

Can 64b/66b be forced out of DC balance by malicious data?

Unlike 8b/10b and 64b/67b, 64b/66b relies entirely on the scrambler for ensuring DC balance. This raises the question: can a malicious data stream force the line to leave DC balance? Or would it ...
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4answers
149 views

Fiber-optic transceiver ICs for applications other than fiber-optic Ethernet? [closed]

When we talk about fiber-optic transmission, we almost always talk about copper to fiber-optic Ethernet conversion using fiber-optic transceivers. But since fiber-optic communication is just ...
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55 views

Testing Ethernet cable with a signal generator and scope

I have been having some problems with my Ethernet lately and would like to test the cable. I was thinking I could borrow a signal generator and oscilloscope from work and get them hooked up to the ...
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1answer
46 views

1000BASE-T MDI Return Loss Measurement

IEEE 802.3's clause 40.8.3.1 specifies a certain a MDI return loss. The specification states that this return loss shall be maintained at all times when the PHY is transmitting data or control symbols....
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1answer
53 views

PHY Register 5 Technology Ability Field Meaning

I have a question about each bit fields(bit 5 to bit 8) of PHY register 5. The following is the description page of a PHY. I know that these fields are Technology Ability Field which is the link-...
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2answers
77 views

Inverting REFCLOCK of Ethernet PHY

A few years ago I had to design a board that uses the NXP LPC1769 MCU and had Ethernet connectivity. I was in need of a PHY chip and the LAN8720 was choosen. During design however, I noticed that NXP ...
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1answer
81 views

LAN9500A Ethernet Adapter

I'm designing a USB-to-Ethernet adapter (actually a prototype of a piece of a larger board). As those following my questions will know, I've had some ups and downs getting the USB part working, but ...
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52 views

LVDS Flex Cables - Optimizing Trace Layout for 10 GbE

I want to run a 10 Gigabit Ethernet (GbE) signal over a 15 pin LVDS flex cable like this one: My PCB will accept an RJ45 connector, and those traces will run over the PCB to the flex jumper, then ...
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1answer
111 views

KiCad Bus on multiple sheets - Are labels the right way to go?

I want to connect bus-lines via several-sheets in KiCAD 5.0 But I don't know whether I got that right. Please consider the following design: Shown in Figure 1 you can see my connection from the chips ...
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2answers
195 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
155 views

Are Ethernet (copper 10/100/1000) compliance tests mandatory?

The IEEE 802.3, for Gigabit Ethernet, and supposedly the ANSI INCITS 263*, for the Regular and Fast Ethernet, have lists of signal quality requirements, which are generally tested using the so-called ...
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80 views

How reliable is using couplers to extend Ethernet cables?

I want to obtain one 90 meters of Ethernet CAT6 cable(with RJ45 connectors) by using three 30 meters of CAT6 cables with RJ45 connectors. The only option I could find is to use three such couplers. ...
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Analog Audio Signal over dedicated Ethernet/Twisted Pair Cable

I need to send an audio signal over 3 meters and back again on the same line (the plan is to put an on/off switch and a volume regulator at the end of the line). Additionally I would like to send 12 ...
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56 views

Servo sometimes freezes when used with another servo and MFRC522 RFID reader

I have looked, Googled and researched all over by now and I have not been able to find anyone experiencing a similar issue to mine, so I thought now would be the time to ask my own question on SE. ...
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2answers
49 views

Fitting USB Data in Cat5 Cable with External Power

I have a camera system at home with a DVR, which connects to a VGA monitor and mouse with which you can read and edit its settings (the cameras can be accessed over the Internet). I've been trying to ...
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2answers
71 views

Ethernet transformer saturation at low frequencies

I am using a 10/100BASE-T Ethernet transformer TG110-E050N5RL (Circuit A in the datasheet) in a circuit. I am applying a 60 Hz 500 Vac hipot across C9 (T1 pin 16 and T1 chassis ground) as shown here: ....
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1answer
140 views

Do I need 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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1answer
127 views

Internet Radio Device with batteries [closed]

I have an project that I will make connection with Internet and listen a stream(in my case IP:port online radio station) then decode the music and transmit it to speakers connected to the ...
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2answers
148 views

Use crystal or oscillator for a Ethernet PHY?

I've saw so many reference designs use just a crystal to generate the clock for ethernet phys, though they can be generated with a crystal oscillator too. Such as KSZ9021's 'XI' and 'XO' pin. Are ...
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2answers
118 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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1answer
138 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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50 views

Incorrect ethernet crc code

I am trying to use the ethernet phy on my FPGA. I am at the point where I can receive a frame. The frame I can see using chipscope matches the data of the frame sent from my computer which I can ...
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1answer
80 views

differential routing without GND

I have task that I need to make adapter board which transforms gigabit ethernet connector RJ45 to another connector (not RJ45). I also have power connector to carry power one side to other. I need ...
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2answers
507 views

Manually test computer Ethernet port with a multimeter

I have updated the drivers for the ethernet port an a laptop at home, yet it is only letting 10 mbps through for every cable that is connected, even though Speed/Duplex was set to Dual 1 Gb. I now ...
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1answer
267 views

Implementing 1000BASE-T (Twisted pair) over PCB backplane [duplicate]

Problem: We are designing a small payload which will contain several ethernet capable devices connected via a backplane we must design. All guidelines concern the scenario where the PHY is ...
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3answers
39 views

TX_ER in GMII interfaces

I'm working on an FPGA MAC module and I'm kind of confused with TX_ER signal. A '1' in TX_ER means there's a whatever error in the current packet being sent by MAC. To my understanding, a MAC frame ...