Questions tagged [phy]

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10/100Mbps Magnetics with 10/100/1000 PHY

I have a SOC that has a KSZ9031RN PHY, that is a Gigabit PHY. But I'm going to use only in 10/100 Mode with 4 wires. Gigabit PHY datasheet recommends a magnetic for Gigabit Ethernet, that are ...
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0answers
16 views

How is the DLL used in MIPI C-PHY or D-PHY?

I guess the title says it all. I can't seem to find how exactly the Delay Locked Loop (DLL) is used inside in one of the MIPI PHYs. Thanks.
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0answers
60 views

PHY Link only establishing 10 Mbps speed when both devices 100 Mbps capable

I've designed a circuit board with a Microchip switch (KSZ9897) going to a Ethernet-to-VDSL module (LX200V20). The PHY ports between the two devices are connected using a transformerless connection ...
0
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1answer
62 views

Why this evaluation board use different track impedance than the right one? Ethernet PHY, routing

Im doing a design with a implementation of 1Gb ethernet switch, for that I bought a evaluation board to do it well. The problem is that in the layout of the ev board I can check that the track ...
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2answers
138 views

Single pair ethernet (SPE) PHY with ESP32

can I connect this Single Pair Ethernet PHY http://www.ti.com/product/DP83TC811R-Q1 to a ESP32 chip? Do I miss something? Does anyone already know a Switch for Single Pair Ethernet? Looking forward ...
0
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1answer
41 views

OFDM symbol period and minimum burst durations

I have been reading about cognitive radio using OFDM and literature on technologies like LTE and 802.11 variants. A useful value in the system analysis is the OFDM symbol period \$T_u\$. Is it ...
3
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1answer
147 views

Design ethernet switch for multiple devices on pcb?

I'm working on a pcb design with a Raspberry Pi CM module and a microcontroller with ethernet capacity. The goal is to connect the devices to the internet. I'm currently using a normal ethernet ...
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0answers
118 views

LAN8720A - Reset and Power-up Issues

I am developing a new board that uses an STM32F427 MCU and the LAN8720A as an ethernet PHY. This is my first design with this MCU, but I've done multiple designs with this PHY and other MCUs. I never ...
0
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1answer
93 views

Why is Logical root sequence number in Root Zadoff-Chu needed?

I have been investigating RACH preamble planning and the properties of Root Zadoff-Chu sequences as used in 3GPP LTE. From Wikipedia, Zadoff-Chu sequences have the following properties: The auto ...
0
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1answer
71 views

Ethernet magnetics [duplicate]

I am working on a system prototype which includes two ethernet switches (KSZ9896) to provide Ethernet Gigabit connectivity between several devices (let's call them slaves, from now on); every slave ...
2
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1answer
876 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 ...
0
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1answer
148 views

How to connect the PHY crystal for RMII?

I'm attempting to implement Ethernet communication for the first time and have run into an issue with my PHY. I'm using the KSZ8091RNBCA. According to the datasheet, when running in RMII mode, the XO ...
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2answers
695 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/...
1
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1answer
97 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
118 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 ...
4
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1answer
376 views

Should I 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 ...
2
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2answers
366 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 ...
0
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2answers
153 views

RSET pin function of RTL8211E

I'm using Realtek's ethernet PHY RTL8211E, but can't figure out what's the purpose of pin 'RSET', and how to connect it. The only datasheet I can find is here. It's wired I can't get that datasheet ...
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1answer
125 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 ...
2
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1answer
386 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
442 views

Lan9500 to Switch (KSZ8795) MII wiring

I'm an experienced analog/power designer that's been asked by a coworker to scrub a digital design. He's pretty junior, but a good friend, so I am helping. (So now we're BOTH in trouble. ;-P We ...
0
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1answer
390 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. (...
0
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1answer
110 views

Direct connection between two SFP+ cables [closed]

I have been reading a lot about modern fiber networking recently and I have a clarifying semi-hypothetical question: Imagine I have two 3-foot sections of Multi Mode Fiber, and four SFP+ 10G ...
3
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1answer
890 views

Ethernet Transmission with one MAC and Multiple PHYs

I have been recently learning about ethernet subsystem. I see that the MDIO interface is shared across multiple (upto 32) PHYs from a single MAC and each PHY's state can be accessed using the 5-bit ...
3
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1answer
176 views

Correct Ethernet Jack + Magnetics for 100Base-TX

I've been shopping around for Ethernet jacks for use in a personal project. The part specifically states that it's internal PHYs are 100BASE-TX/10BASE-T/Te IEEE 802.3 I understand the basic ...
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2answers
3k views

Differential Pair Length Matching for DP83848I

I'm looking in the datasheet and layout guide of the DP838481 but I can't seem to find where it talks about length matching for the RX and TX differential pairs. It only mentions length matching for ...
1
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1answer
140 views

NIC connection with PHY issue

We have an NIC (computer A) connected to Marvell 88e1116R via Ethernet cable, the Marvell chip is then connected to Xilinx FPGA, the FPGA connected to ADSL Analog front end (AFE), the AFE is connected ...
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2answers
92 views

usage of at24c02 eeprom with ethernet module

ı design a altium circuit schematic which consists of lan8720 tranciever rj45 and also at24c02 eeprom .However ı dont know exactly what MAC means and what it does. Why do we use eeprom with ethernet?...
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1answer
69 views

Ethernet Switch used for CCA to CCA comm without FPGA/Proc for MAC

I'd like to connect Ethernet between devices through magnetics without the FPGA or processor involved. For example, I have several off board (PWB) Ethernet signals coming onto my board and then onto ...
0
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1answer
849 views

Purpose of QSGMII

I do not understand the purpose of QSGMII. QSGMII is supposed to combine 4 SGMII signals from 4 MACs into 1 QSGMII signal at 5 GHz. However, there is no Ethernet standard that works at 4 (or 5) GHz. ...
0
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1answer
412 views

SGMII, MDIO and link training

I am reading this document : https://www.nxp.com/webapp/Download?colCode=AN3869 I got this link from NXP support, but I did not get a precise answer to my questiosn and I would like to be sure : The ...
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1answer
248 views

Should I remove terminating resistors in ethernet TAP?

I would like to design Ethernet TAP, with PHY, that I can connect to FPGA via RGMII interface. I know, that I could do this like there, but I would like to be able to analyze low level data in MAC. ...
1
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1answer
1k views

Does SGMII use MDIO?

I was reading the SGMII specification and the documentation of a Gigabit MII to SGMII converter (see MAX24287). I do not see a MDIO to control the registers of the PHY (Basic Mode Status Register, ...
3
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1answer
137 views

How might an LPDDR2 PHY be designed?

I was reading the LPDDR2 spec today out of curiosity. While browsing the spec I became curious about "how might one hypothetically design a minimal working LPDDR2 PHY on paper/for simulation, perhaps ...
6
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1answer
609 views

Why are there different Ethernet PHY magnetic configurations?

I'm looking at pcb-mount Ethernet ports like these: I'm seeing a few different configurations of the magnetics within the ports. On a single Wurth data sheet, there are 4: Schematic 2 is the part we ...
1
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3answers
1k views

Ethernet PHY/MAC/SWITCH IC available?

I'm wanting to use an ethernet switch/Phy LAN9303 to output 2, maybe 3 ethernet signals. I know that I need a 25MHz clock, supporting resistors and caps as well as the magnetics, but I want to know if ...
1
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1answer
908 views

What do pull-up and pull-down resistors do in an ethernet PHY?

I've noticed that most ethernet physical layers (i.e. the interface between the MAC/network and e.g. an RJ45 connector with magnetics) have pull-up or pull-down resistors on the TX and RX lines. For ...
2
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1answer
1k views

GMII/RGMII TX_ER signal: guaranteed functionality?

I have a question seeking to clarify EXACTLY what happens during a GMII exchange between MAC and PHY. Specifically, regarding the TX_ER signal. IEEE 802.3 Section 3: TX_ER is driven by the ...
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1answer
2k views

Ethernet: distance from PHY to magnetics

I am confused as to the preferred placement of Ethernet PHY and magnetics. I thought that in general, the closer the better. But then SMSC/Microchip app note (http://ww1.microchip.com/downloads/en/...
2
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1answer
506 views

Is PHY always needed?

If I'm sending UDP from a microcontroller to another (both have built in MAC, STM32f4 Discovery boards to be precise), must I have a PHY attached to both or can I get away with only sending a MII ...
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1answer
197 views

Can a same phy be used for IPV6 and IPV4?

Currently I am using LAN8720 from microchip in my device for IPV4 network?Can same PHY work with IPV6 network? If yes the why? and if no then what can anyone suggest me a decent chip for it? Thanks
1
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1answer
740 views

MAC PHY defenitions

from Wikipedia: The media-independent interface (MII) was originally defined as a standard interface used to connect a Fast Ethernet (i.e., 100 Mbit/s) media access control (MAC) block to a ...
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1answer
165 views

Ethernet PHY Layer Compatibility

I have two different embedded devices with ethernet connection. One is based on Texas Intruments DM648 DSP chip and the internals of the other are unknown to me. When I connect each one of them ...
1
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1answer
862 views

How to test Ethernet PHY's MDI interface through JTAG Boundary scan

We now use SCANWORKS Boundary Scan Tool from ASSET to make Ethernet SWITCH's manufacturing test. But in almost all PHY chips from broadcom corp, the MDI interfaces are "Linkage" bits. It means that ...
1
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1answer
975 views

Switching between two Ethernet magnetics and one simple Phy

I'm deep into a project and I would like to ask how can I switch 2 ethernet interfaces to single PHY. I know that there're some suitable analog switches for this purpose like MAX4890, but I don't ...
4
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1answer
299 views

Ethernet components location

The normal ethernet components configuration: MAC <-> PHY <-> Magnetics <-> RJ45. My RJ45 connector must be mounted on the system box's front panel, so there must be a wire routed from the ...
2
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2answers
2k views

how to implement Ethernet with PIC, PIC18F97J60, PIC32MX(795F512L), ENC624J600, LAN8720A

My project is a data logger board which must mount a PIC of some kind to provide USB and Ethernet as a means to communicating with the board. I can develop this system into two products a low-end ...
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0answers
1k views

PHY device not responding to MDIO

Update: I have read more about this and what I can conclude is that the phy IC is not initialized correctly. Still no able to figure out how to initialize phy device. Please go through the code and ...
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3answers
26k views

What is the exact difference between SGMII and 1000Base-X?

I was wondering what the exact difference between SGMII and 1000Base-X is, because both seem very similar. Is the "big" difference only the physical medium they are supposed to be transmitted on? Both ...
0
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1answer
409 views

Termination resistors in Ethernet in Kilo-Ohms instead of Ohms?

When working with Ethernet, whether copper or optical fiber, why are the termination resistors always in a few ohms and never in kilo-ohms? Example: 49.9R on transmit & receive pair of PHY in ...