Efficient Networks SpeadStream 5660 ADSL router. A mod by Santiago Garcia Mantinan (Manty) to reset it from a serial port. Disclaimer ---------- I won't be responsable for any damage that can be derived from the usage of the info you extract from this document. Doing modifications to your router will void the warranty and can cause serious damage to it, so if you make any modifications you can en up with your router burned and without anybody to blame but yourself, you have been warned. Farther more, I'm just a crazy human without the knowledge in electronics to do this (this was the first time I was trying to use a transistor :-), so I'm accepting sugestions on the right way to do it ;-) Why? ---- I don't know what the hell the router guys are doing, they charge quite a lot of money for their devices and one expects them to be stable, however they usually are not what they should. In the case of my SpeedStream it was hanging from time to time, if I was near to it I just had to power it off an on, no major headache, it picks the line quite fast, much more than my 3Com router, wich was more stable but didn't like my DSL line. The problem comes when I'm not around and I want to access my server from the outside, then I get annoyed and I cannot do anything to solve it but phoning home if there is somebody there. Anyway, that was a good solution, so I thought why don't we try to reset it from my linux server, which even though is an old server with overclocked micros without fans on them, runs Linux (Debian unstable) and is much more stable than the routers I have tried here? Opening it ---------- To open it you must first remove the big rubber bands that it has in the lateral and that serve as base if you put it in vertical, then remove the two screws, one visible and the other one under the sticker, and then push through the holes the two locks it has by the rubber bands you have removed. Resetting it! ------------- So, you may be asking yourself how do I reset it, I asked myself the same question and found that this router has a reset jumper on it (JP6), the only thing is that the jumper is not there :-( this is placed in the front left of the router looking at the front of it. The reset is produced when connecting one of the pins (!RST) of the DS1708T integrated circuit there to ground. You can see right by the chip the place of the board (JP6) you have to make the short circuit to put that pin to ground. The mod ------- Well, after I found out this I just had to find a way to reset it, even though I could do it via some other means, I choose using the serial port because my paralel port is busy with a printer and using a transistor that should be saturated by aplying voltage from the DTR of the serial port, this pin of the serial port outputs from 5 to 12V when active and from -12 to -5V when inactive (default state), following the logic of the rest of the serial port. Well, so I got the components (transistors and resistences) from a burned old power suply that was around and started making some tests: First test: I used a NPN transistor with a hfe of about 250, trying to get it cut-off on the default state and saturated when the DTR was active, I got this working on my tests, but when I tried it on the router the result was not stable. I was trying to put 3.4 volts on the emitter and 0 on the base to force it into cut-off, but I realiced that when the base was not connected to any stable power, if I touched it with my hand or with an unconnected cable, I could drive the transistor active and the router was reset (I'm blaming the high hfe of the transistor on this, comments are welcome). GND | ^ | / D --\/\/\/----|< | \ | !RST Second test: Anyway, I didn't have any other NPN transistor around, and it seemed easier to make it stable with a PNP transistor even though the meaning of the voltages of the DTR for my circuit would be inverted, thus when the DTR is inactive I get a reset in the router and when the DTR is active I get the normal state in the router. This means two things, first one is that whenever the server is reset the router is automatically reset and for some time (till the server is up again and the controlling software is running again), and second, that I can still use this port for a modem or some other device as the DTR is up when you are using a modem, the normal state for our circuit :-) I had a PNP transistor wich had a little less hfe, around 220 if I recall well, so I soldered the emitter directly to the ground of JP6, then polariced the base with the 3.4V I had taken from the big diode (D3) in the router using a 1.5K resistor, and then I also connected to the base a 4.7K resistor wich then was in turn connected to the DTR of the serial port, that way I had the base at 3.4V if my circuit was not connected and that made it stable even when touching it. The collector was soldered to the other pin of JP6, the one that is connected to the DS1708T. That's it, this circuit seems stable, this is for sure not the best way to to it, it was my first circuit with a transistor in it I must admit, so I'd like to know about other posibilities as well. !RST | 4.7K | / DTR --\/\/\/-+----|< | | \ D3 --\/\/\/-+ ^ +3.4V 1.5K | GND To solder to !RST of the DS1708T and to GND I used the pins of JP6. Contact ------- This document was taken from http://manty.net you can find there the way to contact me if you want to make any comment about the circuit, as the disclaimer says... no claims of responsabilities, please, they'll be directed to /dev/null. Also at http://manty.net you'll find a link to the soft I have written to reset the router when it hangs. Hope this helps in some way to someone. Regards!