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.
48
votes
6answers
7k views
Should chassis ground be attached to digital ground?
I'm working on a PCB that has shielded RJ45 (ethernet), RS232, and USB connectors, and is powered by a 12V AC/DC brick power adapter (I do the 5V and 3.3V step down on board). The entire design is ...
25
votes
2answers
4k views
Why Are Ethernet/RJ45 Sockets Magnetically Coupled?
As the title says really, why do ethernet sockets need to be mag-coupled? I have a basic understanding of electronics, but mostly, I can't figure out the right search terms to google this properly.
24
votes
16answers
19k views
What is a good microcontroller for Ethernet applications?
What is a good microcontroller for doing Ethernet applications? Or do I just need a good Ethernet library to connect with an Ethernet MAC/PHY?
18
votes
3answers
701 views
Microcontroller with both ethernet and radio onboard?
Does anyone know of any (reasonably low-cost) SoC which combines all of:
Microcontroller (any architecture, at least 4KB RAM/8KB flash)
Radio transceiver (433MHz - 915MHz or 2.4GHz)
Ethernet MAC + ...
16
votes
8answers
6k views
Cheapest way to add wifi to a project [duplicate]
I need low power wifi for a not-very-data-intensive application. What modules or chipsets should I look at? Other than low cost and low power, I have no restrictions. The cheaper the better.
This ...
11
votes
3answers
419 views
Why is Ethernet So Power Hungry?
I was just perusing the Microchip ENC28J60 Ethernet Controller datasheet and saw that the operating current can be as high as 180mA while transmitting and 120 mA typical while active but not ...
11
votes
1answer
254 views
Reasoning behind Ethernet pair order
An Ethernet connector seems to use a surprising choice of signal placement in its RJ45 connector. Does anyone know the reasoning behind:
The decision to make pair 2 straddle pair 1?
Why Ethernet ...
11
votes
3answers
313 views
Do magnetics connectors exist?
Conventional connectors, where the plug and socket have metal parts which touch, suffer from the following problems:
Limited mating cycles or expensive plating.
Impedance mismatch (relevant for high ...
10
votes
7answers
2k views
Communication between multiple microcontrollers
I'd like to start implementing a system consisting of N microcontrollers (N >= 2 MCUs), but I would like to know the possibilities to let them communicate one with the other.
Ideally, (N-1) ...
9
votes
2answers
346 views
How could I power an IC over the Ethernet?
I was looking foward to powering a small Integrated Circuit using only the power provided by the ethernet outlet of my room. Is that even possible?
I've googled and I've found that the voltage that ...
8
votes
4answers
499 views
What is needed to go from single Ethernet to many?
I have an embedded Linux system with a single Ethernet port, but I need to go to many ports. It is obvious I need to add magnetics and ports. The trickier parts follow.
My processor has an on-board ...
8
votes
6answers
3k views
Arduino or PIC microcontroller?
I was thinking of creating a surveillance mobile robot. And I am having a problem of choosing a PIC or a Arduino microcontroller. The surveillance mobile robot is controlled via wireless fidelity ...
8
votes
1answer
166 views
Is a 10GHz clock required to drive a 10Gb serial pin?
I am reading about the 10Gb/s Ethernet PHY for Altera FPGAs (datasheet here). I was impressed to know that, at the hardware level, the 10Gb/s is done serially.
Naively, I would think to do 10Gb/s ...
7
votes
4answers
810 views
Difference between Hz and bps
Does Hz and bps mean same? Can a signal be transferred at rate of say Mbps on a channel bandwidth of few Khz?
7
votes
2answers
4k views
Best development board for ARM9?
I am looking for a cheap but powerful dev board for an ARM9 processor. It needs to be able to run linux. I am unsure about the exact specifications for RAM and such(thats partly why I'm posting this ...
7
votes
3answers
409 views
hacking an AUI network port
Does anyone know what's entailed in connecting a computer that has only an 'AUI' network interface into a modern LAN? By AUI port, I'm referring to one of those 15-pin D connector arrangements that ...
7
votes
2answers
322 views
Do I have to worry about the depletion of IPv4 addresses in embedded applications?
We're nearing the exhaustion of IPv4. What should be my concern about it for embedded devices?
I don't know about others manufacturers but until today, Microchip TCP stack doesn't implement the IPV6.
...
7
votes
2answers
217 views
Interesting 100Mbit Ethernet failure
I have a PCB designed using both 10Mbit and 100Mbit Ethernet, I have produced 100 boards 97% of which work perfectly (both 100Mbit and 10Mbit). On 3% of my boards the 10Mbit operates all the time, but ...
7
votes
2answers
1k views
Connecting ethernet to AVR
I am getting pretty familiar with microcontrollers and now want to connect it to the internet. What are the minimum requirements for a microcontroller to be able to do this, specifically, an AVR one ...
7
votes
2answers
1k views
Poor eye diagram, where to start looking?
I'm trying to debug a 100Mbit ethernet board and I'm running up against a problem I'm having trouble trying to resolve.
This is the eye diagram for the transmit pair. The receive pair is very ...
6
votes
4answers
1k views
Embedded System that is able to connect to the internet
I am thinking about starting a project and was just looking for some general input. Where I work our company currently have remote stations that take data in from a radio link and input the data to a ...
6
votes
3answers
341 views
Smallest PIC which the TCP/IP stack can be implemented
What is the smallest (size) PIC with internal oscillator available which the TCP/IP stack can be implemented (and used) successfully? Also, what is the smallest (size) PIC with internal oscillator and ...
6
votes
2answers
451 views
Ethernet Without Magnetics?
How / can you connect Ethernet devices together without magnetics? How do you wire it up? What sorts of practical limitations are there on doing this?
To clarify, I'm not trying to connect two ...
6
votes
1answer
719 views
(Why) does this design suck?
I'm designing an Open Hardware door-lock-controller for our hackerspace, to these basic requirements:
Be made exclusively from available and inexpensive parts.
Read external Wiegand keyboard
Read ...
6
votes
2answers
129 views
Is it worth going to so much trouble with Ethernet differential tracks?
I am laying out a PCB containing an Ethernet connector with integral magnetics, and a Micrel KSZ8051MNL Phy. This is for a 100mbps application.
In an attempt to reduce EMI, and make the Ethernet data ...
6
votes
3answers
3k views
Wiznet W5100 vs. Microchip ENCx24J600
What are pros and cons using Wiznet W5100 or Microchip EncX24J600?
It's a bit complicated to explain.
My question is about the performance of Microchip TCP stack vs Wiznet TCP/IP core on the chip. ...
6
votes
2answers
172 views
USB vs Ethernet cable length
I was talking to a colleague about the limitations of USB cable length and as far as I could remember it was limited by the tight window the host requires the device to respond in (mentioned here).
...
6
votes
4answers
410 views
Is FCC-accredited testing required again if circuit board is placed in a different package?
I am considering enhancing a commercially-available device so that it can be installed outdoors. The enhancement would be to seal the product inside a resin case to make it weather-resistant. The ...
6
votes
3answers
3k views
Ethernet Layout Guidelines
I'm working on a DC jack powered Ethernet design and I've downloaded many Ethernet Layout guidelines from many semi vendors with varying recommendations. I've read app notes recommending almost every ...
6
votes
1answer
133 views
How to increase distance between PHY and RJ45 for GbE?
The PHY I will be using is unfortunately far away from the front panel RJ45 jack (with integrated magnetics). Approximately 13 inches. This is over the maximum recommended distance between the PHY and ...
5
votes
3answers
267 views
Ethernet connector and transformers
I'm working on an Ethernet connection for a PIC18F4620 with the ENC28J60. I found a useful article here, with a schematic:
I see I need transformers between the RJ45 connector and the Ethernet ...
5
votes
2answers
27 views
Ethernet.begin() only works with SD Card removed - why?
When I run this code on my W5100 Ethernet Shield:
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
void setup() {
Ethernet.begin(mac);
}
it only works ...
5
votes
2answers
761 views
Which pair of an Ethernet cable does a router transmit on?
I've seen numerous articles about straight-through and crossover cables and why they are needed. With conventional straight-through cabling, one device transmits on pair 2 (pins 3 and 6) while the ...
5
votes
3answers
2k views
How important is the shield on an RJ45 connector?
If I am going to use a PCB mount RJ45 connector for 100mbps Ethernet, does it need to be a shielded connector, or can I get away with using an unshielded one?
Is there some standard which deals ...
5
votes
1answer
244 views
Runing network cable near X-Ray equipment
My mother runs a small veterinary clinic. She is getting a new X-Ray machine that will need a network connection to send digital copies of the X-Ray to the server. I will be installing a wall plate ...
5
votes
1answer
246 views
What are the 49.9 ohm resistors for in this circuit?
I was wondering what do the 49.9 ohm resistors do in this circuit? Are they absolutely required since I don't have any that size.
5
votes
2answers
1k views
Disabling trailer protocol when using this W5100-based Ethernet shield
I have an Arduino Duemilanove (ATmega328) and Ethernet shield (based on the WizNet W5100). My network gateway is a D-Link DSL-G604T.
Using this setup, I can contact computers on my local network ...
5
votes
2answers
72 views
How to connect RFduino to internet?
I backed the RFduino project on Kickstarter to use it in my next project. It is basically a tiny Arduino compatible board with built in Bluetooth LE that supports additional shields.
I've also got a ...
5
votes
1answer
493 views
DP83848 (Ethernet PHY) 1-bit serial receive data in 10Base-T
Having trouble getting a National Semi DP83848J working in 10BASE-T mode.
The link partner and local status register agree that the link is in 10Mbps full-duplex mode. However, instead of receiving ...
4
votes
1answer
567 views
DIY POE 8 port switch
Hey all i am trying to modify a Netgear GS108 8-Port gigabit switch with POE on 4 of the ports. Problem is that when i go to test to find out what pins 4/5 and 7/8 are in order to place the positive ...
4
votes
3answers
282 views
Did I Kill My Chip?
I've got an ENC28J60 Ethernet Controller in a circuit I'm building. I was testing it out but when I got to the point of talking to it over SPI with my micro-controller I got utter silence back from ...
4
votes
2answers
795 views
4
votes
3answers
1k views
How do network devices detect whether an ethernet cable is connected?
I have a bit of kit with an FPGA on it which includes an ethernet adapter. I'm trying to diagnose why it's not working and while I do that I've noticed that with an ethernet cable connected to my ...
4
votes
3answers
373 views
For remoting 1000Base-T ethernet connector, is it better to remote PHY from magnetics or magnetics from connector?
I'm in need of remoting the gigabit ethernet connector from the main board to a back end board that has all the other connectors. I plan on doing this with a high speed board to board connector ...
4
votes
1answer
300 views
Why is 1000Base-T RJ-45 pinout scrambled instead of having each diff. pair in sequence ?
I need to make an ethernet connection using a cable about 6 feet long to a small and low power gigE camera. Other signals are required (power to camera and hard trigger) and one cable is better than ...
4
votes
2answers
3k views
Making an Ethernet Shield work with an Arduino Mega
customer question:
I have had no success with the ethernet & saw some fine print
Please note that the current design of the ethernet shield is not compatible with the Arduino Mega ...
4
votes
3answers
389 views
Ground loop problem with Power over Ethernet
I am trying to build a weather station, powered using Power over Ethernet.
Originally I planned to use a Nanode as the microcontroller, but since the Raspberry Pi is so cheap, I decided it was much ...
4
votes
2answers
579 views
Ethernet 100 ohm differential pair layout
I'm finishing off the layout of a board in Eagle which has a LAN8710A 100Mbps ethernet PHY on it. The SMSC documentation is really pretty good but I'm stuck on the important detail of how to do the ...
4
votes
1answer
654 views
PIC18F97J60 Ethernet performance
Does anyone else use the PIC18F97J60 Ethernet capability? If so what kind of RX/TX performance is typical for that chip? I was running the TCPPerformanceRX/TX applications provided as part of the ...
4
votes
2answers
115 views
Industry standard Cat5e cabling
I was wondering about the industry standard for building cabling of Cat5e from the elctrical closet to the end user. More specificly from the patch panel to the wall plate.
I was told at some point ...
