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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Connecting a 2 pair ethernet to 4 pair ethernet
I have a switch that has a 4 wire (2 twisted pairs) ethernet interface which I want to connect to an i.MX8 Plus MPU (GBit ethernet with 4 pairs). I need to design the PCB that connects the MPU to the ...
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How is a differential impedance of Ethernet signals maintained without a ground plane [duplicate]
There was a question I raised earlier over here where an app note suggested to have no ground plane underneath the area between the ethernet connector and magnetics.
So, in that case, how will the ...
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Ground plane below connector and magnetics
I would like clarification regarding the use of planes under the ethernet connections between RJ45 to magnetics.
Documents I referred from here (Figure 3, Page 6) indicate that there should be no ...
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PoE circuit can not connect when using injector
I am designing a PoE powered development board with an ESP32 microcontroller module.
I am using the following circuit for the PoE power supply:
This is a direct copy of the PoE power circuit used by ...
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Ethernet PHY - colliding with itself?
I have an embedded system, that whenever the PHY transmits on the twisted pair, the connected hub indicates a collision, and I see nothing on Wireshark. I am 100% confident it is not a software ...
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Magnetics part with and without auto-transformer
I have 2 magnetics part.
One magnetics is this (Circuit A configuration magnetics) & the other magnetics is this
When I use the Halo part, the ethernet link is not up. But when I just replace the ...
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Ethernet PHY ESD protection, difference in components
I'm using a Würth Elektronik 7498210220A jack (datasheet) and I need to add ESD protection to TD and RD lines of this Ethernet connector (with integrated magnetics).
Application of this Ethernet ...
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Ethernet link down issue [closed]
We have used an AR8031 PHY IC in our design. We have found the issue with Link is not glowing when do the power cycle for the board and Ethernet communication with the port also not happening. Still, ...
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Useing a PoE RJ45 ICM Magnetics but not using it for PoE?
I plan on using the Bel G27-122T-015 (PoE ICM RJ45) but I don't need it for PoE. Can I just leave these pins unconnected? The ICM already has an internal Bob Smith termination.
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Do I need to keep twisted pair ethernet wires consistent down the entire cable?
I have an ethernet cable that is hooked up to a 20 foot long 24 AWG twisted pair cable. The twisted pairs are not twisted to the same wires like in the ethernet cable. Would this be a problem? I ...
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Connecting two ethernet PHY's (KSZ8051RNLU) in RMII back toback configuration
I would like to to connect the KSZ8051RNLU in a loopback configuration with itself, I have read that this is possible with other PHY's. Does the KSZ8051RNLU have this capability? Will it auto-...
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How are PCM signals put onto a wire?
I just want to get a sense of how digital data is physically transmitted over cables using protocols like USB or Ethernet.
I've read that they use PAM signaling (USB4 uses PAM-3, Gigabit Ethernet uses ...
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How do I connect an Ethernet Jack to LAN8720
I'm looking for a way to correctly connect an RJ45 socket to a LAN8720 chip, but cannot seem to find much information in the datasheets. Here is the datasheet for the LAN8720.
And here is a data ...
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Seeing multiple possible locations for SYNC_HEADER in 10GBASE-R
I am trying to implement a 10GBASE-R PCS on an FPGA (Xilinx Kintex UltraScale+ Family). First of all, I understand that the included on-board transceivers provide native 64b/66b gearboxing, so I am ...
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Does AWG affect ethernet cable picking up EMF from electrical lines?
Currently, I have a client running an inappropriate cat 5E cable through a buried conduit, underground from their house to their pool control unit. This conduit also facilitates two lines of 120 V. ...
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Measuring Ethernet Impedance
I have a PCB, which was not designed by me. The Ethernet works intermittently between multiple copies, except for on one, where it works just fine.
I want to start troubleshooting at layer 1, and when ...
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Hot-plugging current - TVS and ethernet
My question is based on this question over here
In one of the comments, it is mentioned,
"TVS on the media side would seem to invite short-circuit currents on hot-plugging. Putting it behind the ...
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Why are the TX+ and TX- pins on my laptop's Ethernet port shorted?
I understand that these are supposed to be differential signals with a resistance equal to the characteristic impedance of the cabling between them. However, using a multimeter to check the continuity ...
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NUCLEO-H723ZG HAL LWIP won't ping
I am having issues creating the simplest setup with this board. LWIP initializes, I can see my static IP address in the debugger. I can detect if cable is plugged-in/unplugged. MPU is configured and I ...
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LAN8742AI-CZ-TR GND pad
I am working on LAN8742AI-CZ-TR. GND pin is "hidden" under the chip. Am I ok to use simple via to the GND polygon on my Bottom Layer (it's a simple 2 layer board)? Eagle CAD is complaining ...
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Inductor without inductance
I am trying to find the right component for this inductor. It doesn't show inductance which is bit confusing for me. Which part should I pick for this if I wanted to use it on my PCB?
it's from
NUCLEO-...
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Connection between MCUs with PHY peripherals
I plan to use a MAC TO MAC communication. RMII is decided to be used.
One processor is SAMA5D27 and the other is S32K148.
The signal connections seems to be OK.
But would this configuration work? Also ...
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How to chose the correct value for configuring burst ETH-DMA accesses for STM32F207?
I'm checking the default configuration of an ethernet communication project based on STM32F2 microcontroller (stm32f207 RM0033
UM). Where the comments I'm gone to do, they could be find on section 28....
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PHY 100MBit Link Problem (LAN8814)
We integrated a LAN switch into our design to be able to daisy chain devices and to use PTP. The switch (a LAN9668) has 2 internal CuPhy that we use. It is controlled using an SPI interface and does ...
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LAN8742a autonegotiation gives a half-duplex mode result when it's espected to be full-duplex mode result
I was testing an ethernet based project PCB that uses LAN8742a xip (lan xip seller link) and a stm32f207zg microcontroller (mcu seller link). We are having some issues when we increase the stress ...
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Ethernet MAC TO MAC Communication between S32K148_SAMA5D27 Schematic Review
I am doing RMII MAC TO MAC Communication between S32K and SAMA5D27.Please find the attached
schematic file. Could you please review it.
May I know the level shifters directions are correct or not. My ...
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Broadcom BCM54194 PHY Magnetics
I am designing an application board using a third party Ethernet Switch module. I am unable to get the Switch module manufacturer support on the recommended magnetics to use. I can see that the ...
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Ethernet questions - SPE
I have a question regarding Single Pair Ethernet, is it possible to carry power with two wires?
For example, controlling and powering a motor 12V 0.5/1A
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Implementing TCP/UDP servers with multiple connection in a microcontroller paradigm
I'm facing an ethernet project design based on STM32F207 MCU. The firmware runs a server (TCP or UDP servers) that is constantly asked by 1 to 10 clients. Request and answer payload are less than 20 ...
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How can I find the maximum data rate of a voltage level translator IC?
I am planning to use the NVT2010 in my board for voltage level translation of the Ethernet RMII interface.
We know that the speed of RMII interface is 10/100Mbps. After checking the datasheet, I am ...
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Direct Ethernet link between Raspberry CM4 and Jetson Orin Nano
I need to have high speed communication between Raspberry CM4 and Jetson Orin Nano modules on the same PCB.
My question is: can I route them through Ethernet directly without the need for an isolator ...
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Microcontroller DC analysis Voh(min) from the datasheet
I am doing the DC analysis of my Ethernet interface.
Interfacing SAMA5D2 with FS32K148HAT0MLUT. This is a mac to mac communication.
In the datasheet of FS32K148HAT0MLUT Voh(min) value is not available....
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DP83848 doesn't appear in STM32CubeIDE
I am studying the RMII protocol with Ethernet connection on STM32H753ZIT6. I am using the STM32CubeIDE for the configuration but there is a problem: In "LWIP" -> "Platform Settings&...
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Interface Ethernet voltage
I just want to know what are the voltage levels on the Ethernet differential lines (both single ended voltage level wrto ground & different voltage between the pairs). I haven't measured the ...
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Connection between 2 PHYs - how?
I want to have a PHY-to-PHY Ethernet connection on the same PCB but cannot disable AN and Auto-MDIX (no register access available)?
Use capacitive coupling anyways or use magnetics instead? If ...
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Is this a right magnetics termination for PoE and non-PoE application
I came across the below schematic image while trying to read Bob-smith termination.
Would there be any problems with the termination on the right side with and without PoE?
Can someone explain a ...
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Why do Ethernet PHY magnetics have a center tap?
I've a question with the Ethernet PHY connection to the RJ45 connector.
With either discrete or integrated magnetics, either with voltage mode PHY or current mode PHY, what is the purpose of the ...
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Bob smith termination - Working
I've seen a couple of questions on Bob-smith termination for Ethernet magnetics.
But I fail to understand why the bob-smith termination is required?
Like, what's the purpose and how does the ...
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Value of a ferrite bead in PHYs
I have seen a couple of ethernet PHYs whose manufacturer datasheet recommends placing a ferrite bead on the power supply input of the PHY device whose value is, "Generally, a 100-220Ω (at 100 MHz)...
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RMII to USB conversion IC [closed]
May I know any IC exists for converting USB Type C to RMII. The intention is to communicate between SOM module and micro-controller.
SOM support USB type C and RMII is present in micro-controller.
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Not working IEEE 802.3af PoE-PD Interface Controller (NCP1091)
For a hobby project, I am developing a PoE-powered PCB. At the moment, I have the following schematic and pcb layout designed.
When testing the PCB, I just can't get the PoE to work. My Switch (...
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How to properly retrieve information from an AXI4-Stream interface?
I have got a module with an AXI4-Stream interface. I want this module to extract an ethernet frame from the incoming TDATA signal in order to change some of its ...
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Ethernet external magnetics layout
I am laying out a 10/100Mbps Ethernet PCB with discrete magnetics. From the magnetics to the PHY chip I have a system ground plane on the adjacent layer for the return path. From the connector to the ...
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Would 10 cm of nonstandard wire be able to transmit gigabit Ethernet?
I'm trying to run a Cat 5 cable through a wall.
Bad news is that it is a rented wall so no drilling.
Good news is that there is already a hole in the wall.
Bad news is that the hole is already in use ...
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Ethernet PCB layout: Ground
I am designing a Ethernet PCB with external magnetics on a 4 layer board. On the PHY side I have the system ground on the adjacent layer under the two differential pair for the return path. How about ...
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10/100 Ethernet Routing Review
I know it is a big favor to ask, but this is my first ethernet design, so could you provide input on the routing from connector to mag and from mag to PHY? Is it fine or how can I improve it?
Really ...
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Ethernet transformer RX Centre tap connection to ground
I was going through some schematics that would have a PoE application and stumbled upon the below portion of a PoE camera application schematic.
In the above schematic, we can see the R66 resistor is ...
user220456
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Best Processor for WiFi to GbE Bridge [closed]
I’m looking to build a WiFi to Ethernet Bridge, and did an initial test with a Raspberry Pi 4B. I noticed the CPU was always using less than 10% processing power, which makes me question whether or ...
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Adding communication to a dumb 12V in-line UPS
Edit: By "battery" I mean DC-DC UPS, I did this to avoid any confusion with an AC-AC UPS that would sit before the 12V adapter, but it seems to have caused more confusion. This DC-DC UPS is ...
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What are the rated voltage and current of a single wire within an ethernet cable?
I haven't been able to find a clear cut answer to this question. I've found online somewhere that the entire cable can carry a max of 57V. Each pair can carry a max of 960mA. Is there any validity to ...
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