Technology at a glance!

I have a SpeedSteam 4100 Ethernet ADSL modem in spare after changing ISP as they didn’t want it back. But it seems like my previous ISP had there own firmware downloaded to the modem as I couldn’t get any contact via telnet or http to it. I guess it has been configured as pass-through.

Natually I opened it up to try to locate a JTAG / 3.3v serial port. I found two unpopulated headers and started to poking around with my new Rigol scope while booting it again and again. I found a data pin after a few tries.

I measured a puls width about 115Khz using the the Cursor function in the scope. A simple baudrate “guess” on 15200N81 proved right.

I connected my Nokia DLR-3 data cable converted into a 3.3V JTAG to the pin an beautiful console data showed up in good old Windows HyperTerminal. The RX pin is next to the TX pin. I couldn’t get it to work and a quick view with the scope showed that the HIGH was only about 1.7v, not enough to leave limboland between 0 and 1. It seems like either it draws to much current or it isn’t a normal RX pin. But I was able to send data to the console, although filled with garbage.

I might return to solve this issue another day, but anyway, it was fun poking around in the SpeedSteam 4100 Ethernet ADSL modem.

The console dump shows that my assumption about the ISP specific firmware were correct. This device was populated with a TDC specific firmware.

Benjamin Sølberg FON

I have once before written about how to convert a Erisson data cable into a generic JTAG cable.
Only problem was that it needed 5V and the hardware I use only supplys 3.3V.

Nokia DLR-3 JTAG

So when I found an old Nokia DLR-3 data cable i immediatly turned to my frind Google. What I found was that it used 3.3V which was perfect. The Erisson data cable got its supply from the power adapter (5V) while the nokia flavor got it from the mobile phone.

I found some homemade schematics for a DLR-3 look alike which indicated that it should be possible to use the TX and RX pins alone. I fired up the soldering iron and as the optimist I am, I started to solder female test leads, which i scavenged from the 5V Ericsson converted counterpart.

Half an hour later (thats a lie, nothing only takes half an hour) I was done and ready to test it.

I opened my (working) FON router and after swapping RX and TX test leads everything worked perfect.

The nice part of the DLR-3 is that it gets its supplie from the two other testleads as well, meaning that I didn’t have to use an external powersource as I had to with the Erisson version.

The layout of the Nokia pins I used is : 1(3.3v), 7(RX), 8 (TX), 9 (GND)

Links:

http://www.nokia-tuning.net/index.php?s=cabledlr3 points to a DLR-3 schematics

http://wiki.openwrt.org/OpenWrtDocs/Hardware/Fon/Fonera points to the FON JTAG pinout

http://www.pinout.net/browse.php?conid=66 points to a (now old) Nokia pinout connector.

Please note that the the supply voltage is 3.3V. Luckey for me, thats what is available in the FON router.

Benjamin Sølberg Electronics, FON

Fonera mp3 player & Fonera SC Card hack

http://phrozen.org/fonera.html

Another Fonera SC/MMC hack

http://www.larsen-b.com/Article/262.html

Benjamin Sølberg FON, Network