Ethernet Testing

Page last updated 21 Jan 2010, by Michael Wei. 24 replies diagnostics, ethernet, howto, testing

The documentation on Ethernet is somewhat lacking, so I'm putting together this page as a reference for getting started quickly with Ethernet.

You'll want to download my EthernetTester, which uses DHCP and serves a sample web page, as well diagnostic LEDs and output over serial.

EthernetTester

Rolf's page is a good reference: http://mbed.org/users/rolf/notebook/ethernet/ 
Much of this page is from his page.

Buying Parts

In addition to the mbed, you'll want to get the following, unless you are just cutting up an ethernet cable:

Sparkfun Part#     
PRT-08534           RJ45 Ethernet MagJack
PRT-08790           RJ45 Ethernet MagJack Breakout

Digkey Part#
BC1160CT-ND      CAP .10UF 50V CERAMIC +80/-20% (x2)
P150BACT-ND      RES 150 OHM CARBON FILM 1/4W 5% (x2)
S1012E-36-ND      CONN HEADER .100 SINGL STR 36POS

Getting Connected

Since the mbed conveniently has a Ethernet PHY, you only need to connect the RD+ RD- TD- and TD+ pins to either an Ethernet jack or cable. Ideally, you would get a jack with a transformer (magnetics) as this extends the range of cable you can use, protects the mbed from fluctuations, and is absolutely necessary if you are connecting to a PoE system (you'll fry your mbed otherwise!).

Using a cable

Strip a wire, a connect the following (assuming a straight, non-crossover cable):
Green = RD+
Green/White = RD-
Orange = TD+
Orange/White = TD-

Using a Magnetic Jack

You'll want, in addition to the magnetic jack, two decoupling capacitors, about 0.1uF, if you're ordering from DigiKey, part BC1160CT-ND will work perfect, at a whopping 6 cents a piece. They're useful for noise control, so you might as well order 10 (the minimum). If you don't have the capacitors, the jack will still work fine... you might have problems with some cable lengths.

I recommend getting the MagJack from SparkFun (PRT-08534), it's apparently the cheapest source, at about $2 with integrated status LEDs. If you do get one from SparkFun, you might as well pick up the breakout board for a dollar more. It'll probably save you lots of painful time trying to solder wires onto a jack, though it takes up a bit of space on the board.

Here's a quick schematic of how things need to be connected:
mbed eagle

Connect the following on the SparkFun jack (for other jacks, see Rolf's page):
p1 = RD+
p2 = RD-
p7 = TD-
p8 = TD+

You also need to connect the transformers to +3.3V and also connect a decoupling capcitor between the transformer and ground.
The transformers are on:
p3 = RD0
p6 = TD0

So connect RD0 and TD0 to +3.3V, and also place one 0.1uF capacitor each between them and ground.

Status Lights

The EthernetTester program displays status on LED1-LED4, as well as on p29, p30. If you have a magnetic jack with status lights, connect them to the jack, otherwise, connect them to some indicator LEDs. The assignment of the LEDs are:

p29 = Activity (not used)
p30 = Link
LED0 = Stage 0 (Setting up lwip)
LED1 = Stage 1 (Waiting for DHCP)
LED2 = Stage 2 (Ready to serve pages)
LED3 = Serving an HTTP page

Be sure to use a current-limiting resistor (I used 150 ohms for the SparkFun MagJack).

Running the program

After you have everything wired up, open a serial console, and you should see some status text. After a few seconds, if everything worked out fine, you should get an IP address on the console. Type the IP address in your browser (i.e. http://192.168.1.100) and you should see a test page, with the RTC time, your hardware address, and the current IP address. You'll also see the requests from your browser in the serial console.

24 comments

Mark x
21 Jan 2010

Thanks for posting this!  It couldn't have come at a better time (for me!).  This helps alot...

Any word on how to configure for static IP?

Michael Wei
21 Jan 2010
Mark x wrote:

Thanks for posting this!  It couldn't have come at a better time (for me!).  This helps alot...

Any word on how to configure for static IP?

Yeah,

Edit the lines:
    IP4_ADDR(&netmask, 255,255,255,255);
    IP4_ADDR(&gateway, 0,0,0,0);
    IP4_ADDR(&ipaddr, 0,0,0,0);

To your desired configuration.

Then, replace    

dhcp_start(netif); // <-- Use DHCP

with

netif_set_up(netif);

Mark x
21 Jan 2010

Ahhh..  I missed the netif_set_up(netif);

Thanks a bunch!!  This is a great help!!

 

Mark x
05 Feb 2010

Michael, if you don't mind my asking...  How would one initiate a connection via a specific port to a specific IP address and send a small string to another device using this?

Frank Murphy
07 Feb 2010

I'm not sure that you'll fry an mbed by connecting it to a PoE enabled system. From the little reading I've done on it PoE is only applied after a discovery process (http://www.gocsc.com/uploads/white_papers/59AC05CD861A40CC836B2F85B4DC2BAA.pdf indicates that PoE enabled devices check for the presence of a 25k resistor before applying 48V). Is there some part of the PoE system that I'm missing?

Rick Drolet
22 Mar 2010

Thanks for posting the application and the tutorial!

I am trying this with the LPCExpresso base board which has the RJ45 installed. Something is not right here:

Starting Up...

Configuring device for DHCP...

Interface is up, local IP is 192.168.1.103

Starting Web Server...

Waiting for connection...

But I do not get a web page or any messages. Led4 is off, all others on. There were no errors posted; just a warning mem_sem was not used.

Any ideas as to where to look?

Abraham G.
02 Apr 2010

Hello Michael,

This is the best Ethernet tutorial.

Thank you,

Abraham

Hi,

I tried importing this and keep getting an svn error.

Is there something wrong or just a problem with mbed compiler?

 

Cheers,

Paul

Simon Ford
03 Sep 2010

Hi Paul,

Something is not happy there; we'll investigate.

FYI, Donatien did some good work on ethernet if you look in the new cookbook; that may be a better place to look for some newer and more stable examples.

Simon

Simon Ford
03 Sep 2010

Hi Paul,

This is now fixed!

Simon

George Adams
09 Oct 2010 . Edited: 09 Oct 2010

Hello

I have the sparkfun breakout board for the Magjack and have connected it as described in the above information (good article), but I cannot seem to get the mbed to communicate on ethernet. The program compiles and loads without errors, but seems to hang with the second led on mbed flashing. Using wireshark to watch the ethernet, there is no dchp request being sent from mbed. Any suggestions as to where to look would be greatly appreciated.

 

Thanks

George

Melchior Pau
07 Feb 2011 . Edited: 07 Feb 2011

Had the same problem as Rick Drolet,

I've entered the given IP in my browser, but I just get a blank page. As Rick said, the first 3 leds are on, the 4th is off. Also, the ledLink is on, ledActivity is off.

Starting Web Server...
Waiting for connection...

Edit: I'm using Ubuntu10.10.

Edit2: Ah, fixed. Due to shortage of ethernet cables I had the PC I was browsing on, running on my HTC network, on 3G. Pretty obvious.

So, Rick, do you have your MBED and PC on the same network? In the same router or HUB or whatever? If so, you have to enter the given IP adress in your browser. And BAM:

Congratulations!

If you can see this page, your mbed is working properly.

mbed Configuration

mbed RTC time:Sun Jan 1 00:00:00 1900 (very up to date xD)
...

Cheers,

Melchior

Rick Drolet
07 Feb 2011

Thank you for the hint! Seems so obvious...

Yes, same MBED and PC on the same network & Router. I really don't remember what exactly I was doing.

I need to remount my MBED development to give this a try.

Stefan Goeckeritz
22 Feb 2011 . Edited: 22 Feb 2011
Thanks, I needed this information, especially the static IP stuff!
Wen qian
28 Apr 2011 . Edited: 18 May 2011

Hello Melchior, Rick, and Michael Wei

 

mBed Ethernet Tester 1.0

Starting Up...

Configuring device for DHCP...

Interface is up, local IP is 192.168.1.128

Starting Web Server...

Waiting for connection...

 

Can you guide me how to configure the ip or how to setup? I'm using cross cable direct connect the Mbed to my PC and i'm using Wifi modem..I'm open my browser and type the IP (192.168.1.128), i do not get the web page. It shown

Oops! Google Chrome could not connect to 192.168.1.128

and LED1, LED2, and LED3 is turn ON. LED4 is OFF.

Thank you

Wen

Wen qian
19 May 2011 . Edited: 19 May 2011

Hello Dear All,

I did solved my problem. Following is there setting that we need to follow.

Have a nice day.

Bst Rgds,

Wen

kaf ogunwale
27 Jun 2011

Hi folks,

am connecting my mbed directly to the PC (apache websever installed) through ethernet,

I typed  'ipconfig' on command prompt it gives -  169.254.235.49  could this correct mbed ip address?

else how do I know the correct mbed IP address?

Pls help

Martin Smith
26 Oct 2012

Hi Micheal,

Something has gone badly wrong here - I have imported this program and when I try to compile it I get 695 errors!

What on Earth am I doing wrong???

Martin

Neel Shah
18 Nov 2012

user Martin Smith wrote:

Hi Micheal,

Something has gone badly wrong here - I have imported this program and when I try to compile it I get 695 errors!

What on Earth am I doing wrong???

Martin

I am facing the sane problem but getting half the number of errors.

Can someone please help out?

Ney Palma
14 Dec 2012
Hi michael i need your help. In the mbed ethernet official page the configuration of the pins for PRT-08534 are the follow: 1 TD+ 2 TD- 3 3.3V 4 NC 5 NC 6 3.3V 7 RD+ 8 RD- As you can see there are diferent that the one you put here for the same connector. Im a little confuse. What is the correct configuration for this connector?, i want my mbed to simulate a pc that has a public ip (im using the breadboard adapter for this connector too) Greetins please help me i dont want to damage the rd+rd-td+td- pins of the mbed connecting something wrong
Alan Matthews
19 Dec 2012

Has anyone figure out why the imported program raises >600 errors whilst compiling as I’m having the same issues as shown above.

Help would be greatly appreciated?

Frank Vannieuwkerke
21 Jan 2013 . Edited: 21 Jan 2013

 

user Alan Matthews wrote:

Has anyone figure out why the imported program raises >600 errors whilst compiling as I’m having the same issues as shown above.

Help would be greatly appreciated?

I ran into the same problem. It is caused by folder names containing a dot. I sent a message to the mbed staff and posted the issue on http://mbed.org/forum/mbed/topic/83/?page=1#comment-20881. Will post back as soon as i get more info.

 

Rene H
27 Dec 2013 . Edited: 27 Dec 2013

Hello I tried to import this program but if i compile I'll get this

 

Error: Function "time(std::time_t *)" conflicts with using-declaration of function "std::time(std::time_t *)" in "extras/mbed_00a04e5cd407/rtc.h", Line: 32, Col: 8

 

and this

 

Warning: The format string ends before this argument in "lwip/examples/purehttpc/main.cpp", Line: 51, Col: 9

 

Can anybody help me with this?

Erik -
27 Dec 2013 . Edited: 27 Dec 2013

This code is old, have a look at the new ethernet stack: http://mbed.org/handbook/Ethernet-Interface

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