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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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628 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
54 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 ...
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1answer
100 views

Using SMI to check speed of ethernet phy

I am trying to use the ethernet PHY which comes with my Digilent Nexus 4 DDR, a Microchip LAN8720A (datasheet). I wrote a controller which lets me read and write values to the smi registers using the ...
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1answer
227 views

Ethernet PHY TX & RX pin failures

I am seeing a problem with Micrel Ethernet PHY KSZ8721BLI. Because of some mechanical constraints, the PHY is located near the edge of the main board and a small card edge connector. The board slides ...
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1answer
268 views

Observing ethernet auto-negotiation packets using oscilloscope

In an answer to one of my previous posts seen here: Verifying 802.3 auto negotiation, @Zac67 mentions that by using an oscilloscope I could observe normal and fast link pulses that are sent in order ...
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132 views

Chassis ground and Signal ground isolation for Ethernet signals on VPX PCB

My design requires Ethernet TX/RX differential signals to be routed from Ethernet magnetics to VPX backplane connectors P1 & P2. As per Ethernet PCB design requirements the module signal ground ...
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1answer
70 views

Is there a need to use public OUI numeration for “private” Ethernet ports?

So I'm working on a product which will have two Ethernet ports: One for "public" network, which will be used by the customer, and one internal, within the machine chassis, which needs to be opened, ...
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1answer
257 views

Connecting Two PHY Together

In my design I want to connect a PHY (88E1512) to a switch which contains another PHY (BCM53115M). The devices are separated by a few inches of PCB and will be impedance matched. Both have the same ...
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1answer
149 views

Is hard real time possible with Ethernet technology? [closed]

If I use EtherCAT to control a motor -- say I use RTnet + SOEM to control a servo drive using EtherCAT connectivity -- and the servo drive both controls and reads sensor value, than: is it necessary ...
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1answer
118 views

Circuit to shutdown a ethernet cable

I am a bit new in designing circuits. I am trying to make an interface to shutdown all the signals coming from an Ethernet cable. The design would look something like this: Can this be done using ...
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1answer
92 views

Missing ground in ethernet

Many point-to-point communication protocols are designed to have an electrical interface with data/clock/whatever signals along with the ground signal for reference. For example, CAN is composed of +...
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185 views

Alternatives to RJ45 ethernet connections?

I have a system where two boards need to communicate through a serial bus with several lines --- rates are in the order of up to 3MHz. The boards will be several meters away (say, 3 to 5 meters / 10 ...
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2answers
155 views

What kind of protection do these Ethernet “surge protection” diodes provide?

I was considering a network run outside of my home, and purchased a super-cheap "Ethernet Lightning Protector" because there was little to lose, and I wanted to understand its workings. Below you can ...
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3answers
2k views

What is the fastest arduino to PC communication method?

I am making an application that has multiple i2c sensors controlled by an Arduino Uno. I want to get all of the raw data from the sensors and transfer them to a PC as fast as possible, on which I will ...
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2answers
219 views

How to connect two FPGA boards - VHDL

Hi all, I am trying to figure out a way to connect two fpga boards (like in the image) for a Morse code decoder/encoder. Our first plan was to make the decoding and the encoding in the same board ...
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2answers
243 views

Does 8b/10b decoding take running disparity into account?

What's unclear to me in reading literature about 8b/10b encoding is how it is decoded. How an 8b word is translated to a 10b symbol clearly relies on the running disparity. But when it comes to ...
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0answers
65 views

LAN9512 keeps disconnecting from RPi Compute Module

Main problem I'm using a RPi CM and I connected a LAN9512 to it. However it keeps disconnecting: ...
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349 views

W5500 Ethernet Chip Layout Advice/Help

I am working on a project that includes the W5500 circuit, this is the first time i had the opportunity to layout Ethernet Interface circuits. Schematic: Whole board and W5500 Module Layout ...
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1answer
197 views

Ethernet MII Timings MAC<->PHY

I am a student working on my graduation project, which will need an Ethernet interface. For such job I choose a microcontroller with built in MAC (STM32F777BIT) and for the PHY, the LAN 8740. I have ...
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1answer
314 views

Ethernet PHYs IEEE1588 PTP vs SOF

I currently working on a new design that should support Ethernet IEEE1588 PTP. I was looking for Ethernet 1GBit PHYs with IEEE1588 support when I saw this on TI website: http://www.ti.com/interface/...
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1answer
245 views

USB 2 data over Cat5 cable

I'm looking to extend two USB 2 devices with one 5 meter long cable. From what I've read, one can run USB 2 fine over Cat5e cable (as long as it's <5m). My question is whether it really matters if ...
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1answer
258 views

Protection against EMI

I have a complex EMI problem. There is a RPi Compute Module along with a LAN9512 and GSM modem (M66). Layout guidelines are strictly following the datasheets' recommendations, I don't think there is ...
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1answer
221 views

Routing Ethernet Connections

I am routing Ethernet traces from a Colibri iMX6ULL computer-on-module to RJ45 Ethernet connector (In-build Transformer). The layout design guide says that Ethernet ...
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1answer
666 views

PoE 802.3af injector circuit

I am wondering if this little guy will work or if it will fry my router. Router is a UniFi AC Pro requiring 802.3af Gigabit PoE. I don't have one laying around so I came up with this. Its a voltage ...
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1answer
99 views

MoCa - Ethernet over Coaxial

This is specifically a high-level hobbyist question, I'm not really looking for schematics or anything of the sort. To deliver Ethernet over Coaxial, what sort of high-level designs or common issues ...
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1answer
168 views

How do Free-RTOS and mbed OS handle ethernet?

Do Free-RTOS and mbed OS poll for incoming data to be received (or use interrupts?)? If so, is there a risk that data to be received while the processor is handling another task (e.g. running a ...
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1answer
205 views

How can I make a PoE circuit that is compatible with 24V passive PoE and 802.3at active PoE?

I'm designing a PoE circuit that should be compatible with both active (802.3af/at) PoE and also 24V passive PoE. How can I do this? Can I just use a PD chip that doesn't include a DC-DC converter? ...
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1answer
1k views

100 Ohm diferential impedance microstrip PCB traces geometries in two layer board

INTRODUCTION: I'm aiming to design an Ethernet connected system as a hobby ( ie. plenty of time but not wishing to spend much ). My design constraints would be sticking to a 2 layer 100 mm x 100 mm ...
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0answers
38 views

Importance of ethernet connector and using a different connector with it

I'm working on designing a modular system where a custom camera has a mounting plate that screws on to a mounting plate on a robot. The camera gets power from the robot over springloaded pins built ...
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1answer
1k views

“Tricking” ethernet cable it's disconnected

I have been looking for a solution to "disconnect" an ethernet cable from a port without physically disconnecting it. I'm doing this since I want to reduce power consumption in a project I'm working ...
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1answer
326 views

Is my PCB layout ok? (ATMEGA32U4, WizNet W5500, Ethernet)

I want to design a device that listens to certain network communication and calculates a MIDI clock signal out of this information. The MIDI output is via classical MIDI port or via USB MIDI. I am ...
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1answer
101 views

Can we connect both ASIC and an FPGA both to the same physical output Ethernet ports at the same time? [closed]

I am doing simulation of my research design on single FPGA, in which I simulated two switching chips ASIC and an FPGA. I mean, I simulated single FPGA working as two chips, and connected them so that ...
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1answer
208 views

Using Ethernet Cable in Electronics Projects

I'm building a cue light system (think traffic lights for theatre, media and entertainment industries) and I need to connect outstations (the traffic lights) to the control station (Arduino). Each ...
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2answers
1k views

Determining how much current I can actually run through my Cat6 24AWG Cables in my confirguration?

I want to use a CAT6 (24AWG) RJ45 cable to carry a total of 2A at 48V. As per the AWG Chart, I see that the Maximum amps for power transmission is 0.577A but the <...
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2answers
284 views

Explanation of ethernet transformer signals RDCT, TDCT, RXCT, TXCT

I have seen in a schematic that the RXCT and TXCT are connected to Ground but actually there is no connected no ground to the PCB: Can anyone explain to me what do these signals mean and if it is a ...
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1answer
276 views

Internal physical layer in microcontrollers

I am working on a project and while doing the component selection I realised that many microcontrollers have MAC & PHY layer on the different chip. Except for TM4C1294 microcontroller (there might ...
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1answer
317 views

is MDIO required for PHY?

Most of the Ethernet PHY chips (e.g. LAN8720) provide strapping option to control operation. I am short of IO pins in my uC, and I do not need (AFAIK) to change anything more in the PHY operation. (...
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1answer
100 views

Ethernet transformer differences

Good morning, I have a design using these magnetics over here to filter and isolate the ethernet signal: https://www.mouser.com/ds/2/336/-515468.pdf And I have this other component as an alternative:...
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2answers
1k views

Ethernet RMII on two layer PCB

INTRODUCTION: I'm aiming to design an Ethernet connected system as a hobby ( ie. plenty of time but not wishing to spend much ). My design constraints would ideally be sticking to a 2 layer 100mm x ...
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2answers
202 views

ATmega communication with I2C + extender or with ENC28J60 ethernet module?

I want to communicate between ATmega328P µC's over 'long distance'. The ATmega µC's will be 5m to 20m apart and the total length of the chain will be around 50m with up to 10 ATmega's in one chain. ...
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1answer
179 views

Simple measuring Ethernet throughput

I have STM3220G-EVAL board (STM32F207IG MCU). I'd like to measure (approximately) its actual Ethernet throughput (board <-> Windows PC). I have CubeMX sources. There are several examples (TCP, ...
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1answer
30 views

Ways to connect Arduino / Microcontroller to the Web? [closed]

What are the best ways to connect an Arduino or a microcontroller (PIC...) to Internet/Web. I would like to be able to send and recieve information from the Arduino/PIC to the Web and vice-verse even ...
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2answers
125 views

Ethernet mechanical switch for testing [closed]

We have an application which accepts streams over IP and displays it on the LCD Screen. We want to test the Ethernet plug-in/Plug-out test. Do you know any IC which can simulate someone plugging in ...
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2answers
368 views

Gigabit Ethernet switch unused RGMII/MII/RMII interface

I am working on 5-port gigabit Ethernet switch based on Microchip KSZ9897. As the KSZ9897 is 7-port gigabit Ethernet switch (5 x 1000BASE-T/100BASE-TX/10BASE-Te IEEE 802.3 + 2 x RGMII/MII/RMI) and I ...
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1answer
93 views

Do waterproof RJ45 connectors with integrated magnetics exist?

I've been searching for days and can't seem to find a rugged RJ-45 Ethernet connector with integrated magnetics. Probably it would be good enough if the connector was just potted so water cannot leak ...
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1answer
148 views

mbed Socket Thread

I need to establish an ethernet connection between a host and mbed, where the host can send commands to the mbed (e.g. move forward, move backwards, stop, etc). As there is no telling when these ...
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1answer
54 views

convert from serial modbus to ethernet through plc?

can I use a plc as a converter to convert from serial modbus(RS485) to either ethernet or usb using code ? , the plc is modicon m340 without communication module but the cpu has serial port , ethernet ...
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1answer
847 views

Ethernet magnetics - PHY side center tap isolation

I am designing a PCB that will use a Microchip KSZ9896C 6-port Gigabit Ethernet Switch. In the datasheet (section 7.2) they state that : "the four transformer center tap pins on the KSZ9896C chip ...
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1answer
459 views

Center tap of transformer for Ethernet interface

When you see Ethernet PHY chips' application circuit, you can find out the difference about connecting center tap of transformer. Some PHYs should be connect to the DC power but some don't connect to ...
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1answer
761 views

LAN port tester

Is there any way to make a simple LAN port tester that can plug into an ethernet port and check for connectivity. I dont want to use the cable testers as it require both ends of a cable to be plugged ...