Everything you Ever Wanted to know about Serial - TTL

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Murrkf
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PostPosted: Wed Aug 19, 2009 22:03    Post subject: Reply with quote
Okay...that guy over on the other thread burning the heck out of his header holes scared crap out of me...

http://www.dd-wrt.com/phpBB2/viewtopic.php?t=56779

and I only have a soldering GUN right now...kid stole my pencil...and I don't have any breakaway headers...so...I figured this would be nice and keep me honest.

If you look carefully though...you will notice I have rx to rx and tx to tx....bad. I saw that before I hooked anything up, when I CHECKED MY WORK (try it at home kids) and fixed that. So....now is the moment of truth...



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Last edited by Murrkf on Thu Aug 20, 2009 1:27; edited 1 time in total
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Murrkf
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PostPosted: Wed Aug 19, 2009 22:14    Post subject: Reply with quote
Got nothing.

Perhaps that guy had his tx and rx backwards....Guess I'm going to find out....

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Murrkf
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PostPosted: Wed Aug 19, 2009 22:29    Post subject: Reply with quote
I'm in.

The linked post must have been looking at those connections from the adapter side. The connection picture that I took, that I thought was backwards, was actually corrrect.

I did also go into the windows driver for the com port, in device manager, and set the setting there to the same as in putty. Not sure it was needed.

Now when I boot it up, I get a bunch of data. Control-C doesn't seem to break into it, but at the end, when I hit enter, I get a dd-wrt prompt, like telnet. I guess I will try an erase nvram/reboot command?

EDIT: I checked that linked post again, and according to the schematics, the information on his site is correct. That would mean that my serial adapter information is backwards. Embarassed

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I'm trying to teach you to fish, not give you a fish. If you just want a fish, wait for a fisherman who hands them out. I'm more of a fishing instructor.
LOM: "If you show that you have not bothered to read the forum announcements or to follow the advices in them then the level of help available for you will drop substantially, also known as Murrkf's law.."


Last edited by Murrkf on Fri Aug 21, 2009 14:47; edited 1 time in total
DHC_DarkShadow
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PostPosted: Thu Aug 20, 2009 0:02    Post subject: Reply with quote
barryware wrote:
you got it right..

If you mix up tx & rx it can't hurt anything.. You just won't get any output.


Funny you should mention that, the same happens with my wife. If I mix up the rx and tx she doesn't putout. Laughing

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barryware
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PostPosted: Thu Aug 20, 2009 0:32    Post subject: Reply with quote
Murrkf...

I am not lecturing or anything. I am helping based on my lessons I have learned the extremely hard way.

1st.. Congrats on getting your console running..

2nd... When not sure or experimenting, DO NOT solder the wires directly to the board. If you gotta switch stuff, you run a real big risk of lifting pads and traces. These boards were not build for maintenance.. Always install a header or some sort of pin that you won't have to remove.

Checkout the 350 post where the user wrecked the board.

I must say, using a "soldering gun" vs. a pen, you did a very nice job.

Not bitching.... Just trying to save you the grief I have suffered from time to time..

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Murrkf
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PostPosted: Thu Aug 20, 2009 1:12    Post subject: Reply with quote
barryware wrote:
Not bitching.... Just trying to save you the grief I have suffered from time to time..


YOU are allowed to bitch! And I need the input. You have experience. I don't. I need to learn. And I appreciate the input and the advice I have received in this thread.

I tried to get those holes cleared. I actually heated a metal protractor right on the tip, holding it against that hard OEM solder. It would not budge. I have those leads lightly but reasonably firmly attached. They won't pull off, but a tap of the soldering gun and the will release from the board. As I say, I had to switch them...twice. Shocked But I appreciate the fact that there was risk that I didn't even realize.

(I ordered 400 header pins, BTW!)

Anyways I got it running and just spent about 2 hours researching soldering guns. HAKKO 926 vs. Weller WES51. Still thinking about that one.

So...is THAT what serial gets a person? A telnet prompt? Besides erase nvram/reboot (which worked and I had to reconfigure the router from scratch) what can you do with serial?

Should I have been able to "break" the output with control-c?

Do some routers not "end" with a dd-wrt prompt?

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Mordak
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PostPosted: Thu Aug 20, 2009 1:16    Post subject: Reply with quote
I'm soooo lacking in my knowledge of setting up serial I can do all the soldering no problem but I have to get a ttl device and learn the commands and such. Is there a place where that stuff is documented (commands) like a man page or something? My WRT160NL has a MicroJTAG for which there seems to be no headers or cables for yet so my only other option is serial. Sad
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Murrkf
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PostPosted: Thu Aug 20, 2009 1:32    Post subject: Reply with quote
Mordak wrote:
Is there a place where that stuff is documented (commands) like a man page or something?


There will be when we finish this thread! Shocked

On that micro jtag...see what I did with my 300N in the last linked post in note 1 of the peacock.

I wonder if you can jtag firmware on that 160NL somehow...

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barryware
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PostPosted: Thu Aug 20, 2009 1:49    Post subject: Reply with quote
Mordak wrote:
My WRT160NL has a MicroJTAG for which there seems to be no headers or cables for yet so my only other option is serial. Sad


Headers are available.. The pins are on 0.050 centers as opposed to the normal 0.100 centers..

However.. When murrkf bricked his 300 Razz he had a genius of an idea.. Since his post, I have worked on 3+ routers with that micro header.. here is what I did different:

Just like murrkf, I just used wires, no solder.. Murrkf used cat5 "stranded" wire in which he needed to fold over the end that went into the jtag socket on the end of the cable.

I used telephone "solid" wire. It is a larger gage. I didn't need to "fold" it over to "slip" into the jtag socket (I'm getting horny). As for the other end of the wire that gets "inserted" into the micro header holes, I cut them on an angle, then "spread" the copper conductors with a needle nose pliers.. Cutting on the angle to make a "point" on the end of the wire and flattening the conductor with the pliers, made them "slip in" to the micro header holes on the pcb and were tight.

I'll be back.. I gotta go "ping" myself for a bit Razz

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barryware
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PostPosted: Thu Aug 20, 2009 2:17    Post subject: Reply with quote
Murrkf wrote:
So...is THAT what serial gets a person? A telnet prompt? Besides erase nvram/reboot (which worked and I had to reconfigure the router from scratch) what can you do with serial prompt


I am sure about Soulstace, and I think Frater was part of the conversation, Redhawk chimed in to answer a question I had so the thread can't be that hard to find.

You can flash a cfe via serial but you must 1st have a working cfe to the point that the console runs.

I have only used serial for data capture (testing) and erasing nvram.

We know yo can erase nvram.. I would like to know how to erase or replace the kernel.. Unfortunately for me... I have only "played" with linux via a live CD.. You need to know linux for this stuff.

This is what this thread is about.. How to "get er done"

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barryware
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PostPosted: Thu Aug 20, 2009 14:00    Post subject: Reply with quote
Found it... The serial flash of a cfe.

It was soulstace & rolf, not frater.. Sorry..

http://www.dd-wrt.com/phpBB2/viewtopic.php?t=48689&start=3

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Murrkf
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PostPosted: Thu Aug 20, 2009 17:32    Post subject: Reply with quote
Here is a summary of what was stated about how to serial flash. It is dangerous!

RolF wrote:
soulstace wrote:
may be able to do it with the mtd command.

http://wiki.openwrt.org/OpenWrtDocs/Customizing/Firmware/CFE#1.2.4._Flashing_new_CFE_image



yes, tested and working on wl-500gp :

Code:
mtd unlock cfe
mtd write -f /tmp/cfe_new.bin cfe

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I'm trying to teach you to fish, not give you a fish. If you just want a fish, wait for a fisherman who hands them out. I'm more of a fishing instructor.
LOM: "If you show that you have not bothered to read the forum announcements or to follow the advices in them then the level of help available for you will drop substantially, also known as Murrkf's law.."
Murrkf
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PostPosted: Sun Aug 23, 2009 14:58    Post subject: Reply with quote
How is firmware flashed through the serial? I noticed that some old build were SF? Can this be done on some of the currently unsupported routers?
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I'm trying to teach you to fish, not give you a fish. If you just want a fish, wait for a fisherman who hands them out. I'm more of a fishing instructor.
LOM: "If you show that you have not bothered to read the forum announcements or to follow the advices in them then the level of help available for you will drop substantially, also known as Murrkf's law.."
redhawk0
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PostPosted: Sun Aug 23, 2009 17:05    Post subject: Reply with quote
Don't confuse terminology here.

Serial Flash is generally an 8-16 pin chip...where the normal parallel flash (like most routers have) is 48-56 pins.

Serial Flash has a single Data In pin...and Data Out pin where it pushes/pulls the data bit by bit to the processor register or through a latch.

Parallel flash like we are used to seeing has Many Address lines and many Data lines because it writes to an address in an entire Byte or Word all at once.

OK...now that that is out of the way.

You can flash a flash chip (serial or parallel) with the CFE by using a tftpd32 server. You use the CFE to call the server to grab the data and put it in RAM...copies it to the Flash chip for configuration.

The command for this is
flash -noheader 192.168.1.3:dd-wrt/dd-wrt.bin flash0.os

Where

flash is command name (-noheader is one of that command's switches)

192.168.1.3:dd-wrt/dd-wrt.bin is the IP of the tftpd32 server and file to be flashed to the kernel

flash0.os is the partition on the flash chip to write to.

There are other partitions...and from what I've seen...each manufacture calls it something a bit different....so flash0.os may or may not work in every case....it's rather tricky to flash using this method...I've only been sucessful once.

redhawk



IMG_0381.jpg
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Yellow dot...is the Serial Flash chip on a Netgear WGR614Lv8 unit.
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redhawk0
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PostPosted: Sun Aug 23, 2009 17:49    Post subject: Reply with quote
Some more from my notes...this was used on Asus 500GU.

redhawk

Code:

Flashing CFE or Firmware via Serial Port
where 192.168.1.50 is a linux box running tftp server

CFE
CFE> flash -noheader 192.168.1.50:cfe.bin flash1.boot


Firmware
CFE> flash -noheader 192.168.1.50:linux.trx flash1.trx

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