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 Post subject: Serial Port problems
PostPosted: Mon Jul 30, 2012 7:22 pm 
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Joined: Fri Jul 13, 2012 8:12 am
Posts: 110
Hi,

I'm trying to get the serial port working through J4. I now have 2 UART-USB adapters, one CP2102-based, another with a FTDI chip. But somehow, I cannot get anything out of the serial port - always silence. There are LEDs on the FTDI adapter, TX lights up when I press a key on the computer, but the other one never lights up.
I just connect TX to RX and RX to TX and GND to GND as described in the Wiki. Of course I made sure that the chips I use are set to 3.3v.

I'm sure there is a simple solution to my problem - can anyone help?

Thanks,

Stefan


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 Post subject: Re: Serial Port problems
PostPosted: Mon Aug 13, 2012 10:00 am 
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Joined: Mon Jun 16, 2008 10:45 am
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Maybe an open door: Have you already tried to exchange the TX and RX lines?


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 Post subject: Re: Serial Port problems
PostPosted: Mon Aug 13, 2012 10:09 am 
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Posts: 110
Yes I did, but the Wiki information was correct. After all, I tried with a second HMNHD-CE I had around, and alas it worked. But it only worked about 3 times out of maybe 50 times I tried it. I have tried a lot of combinations of plugging the power in, plugging the converter into USB etc etc.

Eventually I put the power brick of the NAS onto a switchable power plug, and switched it on, if nothing arrived within a couple of seconds, switched off, switched on again. With this, I got it to work those 3 times, but eventually I gave up to not damage the HDD. I figured out without the serial console that in the end that a missing "depmod" call on the target system was preventing the network to come up.

Don't know if there is a adapter which is known to be working better than the FTDI FT230X which I have and which worked (occasionally). I would still like to have a working solution because I'm trying to port another distro to the device, and doing all this "in the dark" is quite annoying...

Stefan


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 Post subject: Re: Serial Port problems
PostPosted: Mon Aug 13, 2012 10:42 am 
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seidler2547 wrote:
Don't know if there is a adapter which is known to be working better than the FTDI FT230X
Well, my FTDI TTL-232R-3V3 never failed on me. (OK, I fried one, but it wasn't his fault)

But I can hardly imagine both your UART-USB devices would fail. Have you ever put an oscilloscope on the TX line? And also, maybe the initial bootloader (which is embedded in the SoC) checks for some status on the RX line before switching on the UART?

Have you checked if console=ttyS0,115200 is in the commandline, even when no serial data is retrieved? If not, you might force it in the kernel init. (Or change the u-boot environment to unconditionally add it)

What does the question mark after 3.3V in the Wiki mean? Is there 3.3V available on that line?


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 Post subject: Re: Serial Port problems
PostPosted: Mon Aug 13, 2012 11:21 am 
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Joined: Fri Jul 13, 2012 8:12 am
Posts: 110
Mijzelf wrote:
Well, my FTDI TTL-232R-3V3 never failed on me. (OK, I fried one, but it wasn't his fault)

Well, from what I understand, the FT230X is just a version with less sophisticated functions.

Mijzelf wrote:
But I can hardly imagine both your UART-USB devices would fail. Have you ever put an oscilloscope on the TX line? And also, maybe the initial bootloader (which is embedded in the SoC) checks for some status on the RX line before switching on the UART?

Sorry, don't have an osc. I have a feeling as well that the SoC does some checking because even when the kernel loads, no serial output ever happens if it doesn't work from the beginning (that means: if I see the u-boot messages, everything works, if not, nothing works).

Mijzelf wrote:
Have you checked if console=ttyS0,115200 is in the commandline, even when no serial data is retrieved? If not, you might force it in the kernel init. (Or change the u-boot environment to unconditionally add it)

It is there.

Mijzelf wrote:
What does the question mark after 3.3V in the Wiki mean? Is there 3.3V available on that line?

Yes, there are 3.3V, I think the original author didn't know why it is there.

I have two suspicions:
1) in some later version, they saved some components (capacitors or whatever) which are needed for the realiability of the serial port
2) it's my cable - I use an old CD-ROM internal audio cable since it has 4 wires (of which I use 3) on a 4-pin header which fits perfectly onto the headers on both the NAS and my converter. I didn't want to solder anything onto pin headers because of possible h/w warranty issues

Stefan


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 Post subject: Re: Serial Port problems
PostPosted: Mon Aug 13, 2012 12:27 pm 
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Posts: 6072
seidler2547 wrote:
1) in some later version, they saved some components (capacitors or whatever) which are needed for the realiability of the serial port
You have the PCB pictures in the Wiki to compare with. Unfortunately those were uploaded by Woody, while the serial port information is provided by Solo. So they might not depict a 'working' serial port. But if it contains components which lack on yours...

Quote:
it's my cable
Nah. That could only be a loose contact. In that case you should see *something* when wiggling the cable while booting.

I wonder why the serial port is wired to 4 different connectors. Do you have a multimeter? Have you checked if they are really on the same copperline? For JP1 and JP2 this seems true, I can see the wires on the photo. JP3 and JP4 seem identical to me. (Except for the pins) I wonder if JP3 could be a 2nd port. In that case you might change the kernel to use a different port. According to the Pogoplug Pro GPL sources the Oxnas chip even has 4 serial ports.


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 Post subject: Re: Serial Port problems
PostPosted: Tue Aug 14, 2012 8:55 am 
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Joined: Fri Jul 13, 2012 8:12 am
Posts: 110
Ok, I got it to work (at least I can see the output now).

BUT it's really really strange: I tried with the CP2102-based adapter yesterday and I noticed that when I do not connect GND, I get lots of garbled data. So after some tests, I found a way to make it work, every time: I disconnect GND, plug the power onto the device, then after some seconds I connect GND - and voila, it works.

Quite annoying, and I haven't got the TX (PC to device) working yet, but I'll try this with the other adapter as well.

I have no idea why this works, though!

Stefan


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 Post subject: Re: Serial Port problems
PostPosted: Wed Aug 15, 2012 6:49 am 
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Joined: Fri Jul 13, 2012 8:12 am
Posts: 110
Alright, tested with the FT230X. I use the same technique as with the other one: I start up with GND disconnected (in this case I can already correctly see the device output), then I connect GND after some seconds and I have the full serial console (TX+RX) working. Finally :geek:

Stefan


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 Post subject: Re: Serial Port problems
PostPosted: Wed Aug 15, 2012 5:38 pm 
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Joined: Mon Jun 16, 2008 10:45 am
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Weird.


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 Post subject: Re: Serial Port problems
PostPosted: Wed Jan 29, 2014 6:12 pm 
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Joined: Wed Jan 29, 2014 6:03 pm
Posts: 86
Hi both!

I'm trying to get this to work with a CP2102 and Putty.
Attached to COM3, did TX-RX, RX-TX and connect GND after some time HMNHDCE is powered on.
But no activity on the terminal window. Serial 115200-8-N-1-XON/XOFF. If I start with GND its the same.
I can see the controller is correctly installed in Win8: Silicon Labs CP210x USB to UART Bridge (COM3)

What am I missing?

Thanks for your help!

P


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 Post subject: Re: Serial Port problems
PostPosted: Wed Jan 29, 2014 9:28 pm 
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Joined: Mon Jun 16, 2008 10:45 am
Posts: 6072
Does your terminal echo when you connect TX to RX?
Have you tried to exchange TX and RX? The specification is often fuzzy.
Xon/Xoff is probably not supported on the box, you should use no handshake. (And certainly no hardware handshake)


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 Post subject: Re: Serial Port problems
PostPosted: Thu Jan 30, 2014 9:17 am 
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Joined: Wed Jan 29, 2014 6:03 pm
Posts: 86
Thanks Mijzelf!
Got it working... classic IT solution: unplug all, reboot, plug all again ensuring spec, and voila!
It works with xon/xoff and with the GND plugged from start, though. Weird.
Now I have a new WD Red NAS 2Tb working in HMNHD-CE !! I'll post details on the other thread
P


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 Post subject: Re: Serial Port problems
PostPosted: Fri Sep 26, 2014 10:37 am 
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Joined: Wed Sep 24, 2014 10:27 am
Posts: 20
Hello, I know I opened another similar thread about serial port issue but i haven't seen this one...

After some time and following the wiki for pinouts I get this with putty:

Image

I use putty from windows with and usb-serial adapter port settings 115200-8-1-N with no flow control
ISO-8859-1:1998 (Latin-1, West Europe) as character set.
I am trying also different speeds character set but I always images similar to the one I posted. Any specific setting with putty I should check or do you think it's not setting related issue?
Any help is appreciated!

Carlo


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 Post subject: Re: Serial Port problems
PostPosted: Fri Sep 26, 2014 11:53 am 
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Joined: Mon Jun 16, 2008 10:45 am
Posts: 6072
It looks like a bad baudrate, but your setting is allright. The characterset doesn't matter, the output of the bootlog is pure ASCII.

When you short RX and TX on your USB-serial cable, do you get a local echo? If not, the cable is not good. I guess you don't have an oscilloscope available?


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 Post subject: Re: Serial Port problems
PostPosted: Fri Sep 26, 2014 1:19 pm 
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Joined: Wed Sep 24, 2014 10:27 am
Posts: 20
It could be, here all the component involved. I have done the soldering myself checked many times, now
http://s13.postimg.org/5rdhj6ipz/pinouts.jpg
http://s27.postimg.org/wh10r1i2r/IMG_20140926_150918.jpg



Maybe the gender changer could be impacting. I am almost sure for the pinouts because in any other config i tried I see nothing on screen but who knows..


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