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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Clock out drive strength - Current

In the datasheet of this IC, what is the benefit or purpose of having 12mA and 16mA drive strength for the clock output pins? What is the purpose of having 2 drive strength values for the clock? Is it ...
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Ethernet Controller - Signals

I was going through the datasheet of this Ethernet controller IC. I see that the pins are different than that of a Normal Ethernet PHY. Usually PHY has Ethernet Tx and Rx signals and has the MII/RMII ...
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Meaning of Speed and Duplex pin in the IC

In this - Link of the datasheet, can someone tell me what is the meaning/purpose of the DUPLEX Pin and the SPEED pin. Unable to understand what it actually does and what does it indicate?
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How to find the maximum power dissipation or Thermal resistance (J-A)

In this datasheet - Link there is no value of maximum power dissipation or junction to ambient thermal resistance. In this case, how to find the value of it?
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High power & ethernet over SF/FTP using the cable's shield

I'm working on a custom gigabit high-power POE solution (ideally 200+ watts). Since SF/FTP cable has a lot of shielding, why not use it as a conductor? Using all 4 twisted pairs for DC+ and the shield ...
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Meaning of Virtual PHY, Managed Ethernet [closed]

Can someone tell me what is the meaning of "Virtual PHY", "Managed Ethernet Switch" & "switch fabric". Unable to get a good clarity on what terms actually mean in the ...
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What is support for an end-to-end and peer-to-peer transparent clock?

In the datasheet of LAN9353, the description states that it supports "supports end-to-end and peer-to-peer transparent clocks" Can someone tell me what is the meaning of this?
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Why is this 75 ohm resistor present in the Ethernet connector? (10/100Base-TX)

In this datasheet (and in other similar) pins J4, J5, J7, J8 are connected to the ground with a resistor and cap. For 10/100Base-TX pinout it seems they are not used (at least for modern of the ...
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Normal Switch and LAN9353

I am reading about the different types of LAN Switches. And I came across the LAN9353 device - Link I want to understand the difference between a normal Gigabit Ethernet 3 port switch and this LAN9353 ...
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VHDL: Which Ethernet data are seen by wireshark?

I want to send data to wireshark. I was able to receive data FROM wireshark at my device I already can send it to a similar device I use and I can see my data "easily" (<-- xD) I just ...
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How to monitor Ethernet packet loss real time on different connections?

For an embedded application we have a network with star topology, where we want to determine if there is packet loss for the different point-to-point (SMAC => DMAC) connections. We consider ...
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Can I use a 50m network cable to power two 24VAC solenoid valves?

I have purchased two 24V AC solenoid valves to control the irrigation in my greenhouse. The plan is to install the two valves inside the greenhouse and power them using relays in the garage which is ...
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Ethernet Switch and QoS Support

I'm going through the Ethernet Switch IC - Link In the first page, under highlights section, it is mentioned as switch is QoS support. When I tried to research on what QoS means on this Link, I found ...
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Differential signalling [duplicate]

This is a similar question to one over here. Posting a new question here, assuming that my question was not clear in that. Can we split a differential signal into 2? Assume the below image: I'm using ...
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Splitting of a differential signal

Can the Ethernet Tx and Rx signals (Using all 4 pairs; RGMII interface) be split into 2 so as to connect to 2 RJ-45 connectors, but only 1 will be used at a time. In general, can we split any ...
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KSZ8081 PHY address configuration

I'm using this KSZ8081 PHY transceiver. I'm unable to understand how to configure the PHYAD[0:2] pin and the B-CAST_OFF pin. As far as I read, the PHY Broadcast address will always be "0" ...
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Ethernet Switch configuration mode

I'm trying to understand the Ethernet Switch product. On page 54,55, we can see that, the MAC signals, Like for MII and RMII interface, we can understand that the digital MAC port 3, can be configured ...
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4 votes
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Effect of Ethernet PHY interface on the speed of Ethernet

I have been working on this new project where I need to include Ethernet. But the microcontroller of my project doesn't have any Ethernet PHY included (no MII, RMII, GMII, etc.) So, I am instead using ...
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Ethernet Switch IC

I'd like to understand a little more on the Ethernet switches. Consider this Ethernet Switch which is a 3 port switch. Like, it has 2 copper ports and one digital (MAC side interface) port. It is ...
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RX_ER peripheral not used in RMII

I'm using this PHY and MAC in this Controller The Controller does not have the ENET_RX_ER peripherals in the 100 pin package. In that case, can we handle the RX_ER in RMII interface using a GPIO port ...
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1 vote
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What are the recommended differential trace characteristics for Power over Ethernet input section?

I've been looking through a few application notes for Power over Ethernet front ends such as Microchip AN3468 and Skyworks AN1130. I can't figure out what the characteristic impedance of the ...
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How to combine SIM800L and Ethernet shield in one program?

I'm trying to use a SIM800L and Ethernet shield in one program. Separately they work perfectly, but they do not work together. When I put the following code in the ...
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STM32 + LwIP + DP83848 - No results when I ping

I have made a PCB with an STM32F407 processor and I have been used DP83848 Ethernet PHY. For STM32F407 processor. I have selected RMII settings. The pinouts for the RMII settings. Red rings got to ...
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2 votes
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Two devices sharing the same coaxial cable, what frequency channel should I chose? [closed]

The 2-stories house is equipped with a coaxial cable that has wall plugs in 1st and 2nd floors (it's also connected to the antenna on the roof). Our IAP installed a modem for Internet (Arris CM820C) ...
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Media Independent Interface

I'm reading about the PHY, MAC and the MII interface. I understand that the MDI interface from the RJ-45 to PHY will be 10Mbps, 100Mbps or even higher to 1Gbps. But when this data signals move to the ...
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Working of this Circuit - Reset

I'm using this Ethernet transceiver PHY to study the working of the RGMII interface. Can someone explain the working of figure 18 on page 75? What is the purpose of D1 and D2 along with the RC? How ...
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Ethernet 100 BASE-TX Question

I'm using this Ethernet transceiver PHY to study the working of the RGMII interface. I just want to understand 2 things. 1. What would be the output and input differential voltage levels on the pins 2,...
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Current on Ethernet cable between devices (100Base-TX /10Base-T)

Curious about the amount of current on the Ethernet cable between devices using the 100Base-TX standard and separately the 10Base-T standard. I realize these are differential signals and 100Base-TX ...
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Compatible High-Power PoE Ethernet Magnetics and PHY

I'm building a high-power (~70-90W) PoE system, anticipating 4-pair power (Type 4 PoE) and am working to select a combination of high-power capable magnetics that is compatible with a basic 10/100 PHY....
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Marvell 88E6097F switch and AR8033 PHY

I'm trying to design a 6-port Fiber switch. For this I chose the MARVELL 88E6097F which is an 8-port switche+3GE. My problem is that the CPU (IMX8M-P) comes out from the SOM with a PHY (AR8033). Is it ...
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Isolation voltage to distance conversion

Introduction: I am designing a board with a standard IEEE 802.3 1000Base-T ethernet interface. The board is a standard 4-layer FR4 board with all components on top and GND on Layer 2. The IEEE 802.3 ...
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Ethernet PHY - Buffer Type

I'm going through the datasheet of this PHY Transceiver LAN8701A On Page 14, table 2.2, it is mentioned as buffer types. This is the first time I'm coming across the table called buffer types. Can ...
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How Ethernet uses full bandwidth of the link if one host is sending more than one frame for different hosts? [closed]

I followed from this question. We know that modern Ethernet is full-duplex. At the same time, we can send or receive the signal. Suppose I consider one LAN where multiple hosts are connected by ...
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2 votes
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STM32 ethernet and TCP issues with firmware 1.27.0 and cubeide (probably at sending messages)

I would like to use the TCP/IP protocol (with LwIP, HAL library, without freeRTOS) in a project but I face some portability issues. I'm starting with TCP echo client example as in chapter 6.1.1 of ...
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Line coding - The purpose and advantages [closed]

I'm reading about the line codes and probably confusing them with combining data and clock. I've read the answers to this question and a few others along with Wiki pages but unable to get a clear ...
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ESP32 2 SPI connnection ethernet shield and usb host

Is it possible to have two SPI connection for ESP32 for ESP32 below link for the product https://www.amazon.co.uk/AZDelivery-NodeMCU-CP2102-Development-Parent/dp/B07ZZFXRTY for ethernet shield ...
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Clock recovery circuit in 100base-t / 1000base-t

I'm trying to understand the ethernet interface. My understanding is that Ethernet is an asynchronous interface since there is no explicit clock signal transmitted along with data. So, when there is ...
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Why do we need to use a 100ohm differential probe to measure ethernet signals when there is not any standard?

I was going through the debugging techniques of ethernet signals and found that we can capture the ethernet signals using a 100ohm differential probe. Why do we need to add 100ohms on the ...
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Smallest lowest cost way to isolate RGMII signals between devices on the same CCA?

I have a single Gigabit Ethernet line coming out of a circuit card. Access to the line will be shared by two CPUs. To facilitate shared access, the CCA will have an Ethernet switch IC. The switch IC ...
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2 votes
2 answers
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Media Independent Interface Signals

For the MII interface signals: I read in Wikipedia - MII on the Tx and Rx signals. But I am confused on why there are two clocks (for tx and rx)? Are the directions mentioned for transmitter signals ...
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Clock data recovery waveform

I've read that a CDR block recovers clock from the data stream. Clock Data Recovery Can someone show me a waveform on how its done? Like the carrier wave and modulation wave in FM and AM techniques, ...
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3 votes
1 answer
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IC to switch from Ethernet port A to port B

I have a PCB that has 2 Ethernet ports (tested card). I'm building a test bench that I will connect to my PC, the goal is to test if the 2 ports are working. The PCB doesn't have Ethernet female ...
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Gigabit Ethernet 1000BASE-T and Fast Ethernet 100BASE-T

I have this basic question. Gigabit ethernet has two things - 1000BASE-T and 1000BASE-TX. And Fast Ethernet has 100BASE-T. Ethernet has 4 twisted pairs. Can someone tell me which are half duplex and ...
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Ethernet connection with discrete magnetics

I'm in the process of designing a carrier board for a raspberry pi cm4. Since I want to get everything as small as possible, I'm planning to use discrete magnetics for the ethernet connection. Looking ...
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100 BASE Tx Ethernet question

I am going through this Wikipedia article - Fast Ethernet and got this below table. Can someone please explain why there are 3 line codes : 4B5B, MLT3 and NRZ-I done? Why all 3 are done? Also can ...
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1 vote
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Ethernet PHY design considerations

I've started to read about Ethernet PHYs and reading the documents and articles available on the web. I've 2 questions: I read that the IEEE 802.3 Standard specifies that the copper cables should be ...
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What is the preferred way to store per device MAC and static IP on a Xilinx FPGA?

I've been writing some Ethernet handling code for Artix-7 FPGAs. As I said in the question I want to, on per device basis, store a device MAC and device IP address. In other words I would like to be ...
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1 vote
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LAN8720A + ESP32 (GPIO 0 Clk Out) RX working, TX not

I have made a custom board with the ESP32-WROVER-IE module and the LAN8720A Ethernet PHY. RX'ing packets work (I see ARP packets etc.), but TX (and therefore DHCP and communication) won't work (I ran ...
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What is the differences between flow control and access control with respect to efficiency?

We first apply access control methods to get access to the channel link followed by the flow control methods to stop the receiver from overflowing. Suppose we are using CSMA/CD in access control ...
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Measuring Ethernet Waveform on a scope

I measured the following waveform on a scope. It is a 100MBps Ethernet signal and I am measuring the TX+ and Tx- signals between the magnetics and RJ45 connector. I see what looks like a double ...
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