No serial connection, terminal is still blank

Discussion about my Wifi Radio project at http://mightyohm.com/wifiradio/ or my WL-520gU talk at NOTACON.
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bola
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Joined: Fri Sep 04, 2009 4:01 am

No serial connection, terminal is still blank

Post by bola »

Hi guys.

I have soldered the pins for serial connection as shown in the guide. But if i open a connection to the usb-serial adapter (have tested two different boards) HyperTerm show nothing.
My settings are 115200 baud, 8N1 and no flow control.
The adapter works with 3,3V.
If i login with telnet and try to send something to the serial interface tts/0 or tts/1 its the same.
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mightyohm
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Re: No serial connection, terminal is still blank

Post by mightyohm »

Try swapping your TX and RX lines and see if that fixes the problem.
richms
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Joined: Fri Jul 24, 2009 3:25 am

Re: No serial connection, terminal is still blank

Post by richms »

Check you have handshakeing disables in the terminal software. Try connecting tx and rx on the serial adapter and see if you see what you type.

Im using a chopped off knockoff of a nokia USB data cable just fine with mine - it just worked - bootloader, linux etc all come thru the terminal package. I used realterm only because I didnt know what to do to make hyperterm install on windows 7, but hyperterm works as well.
bola
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Joined: Fri Sep 04, 2009 4:01 am

Re: No serial connection, terminal is still blank

Post by bola »

Hi.

Handshaking is disabled and tx/rx are correct.
At the moment i have connected the router with my pc over two ftdi's.
if i send somthing from the router to the pc everything is fine but if i try to catch stuff from the pc there comes nothing.
i have configured my serial interface with stty 9600 < /dev/usb/tts/0
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mightyohm
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Re: No serial connection, terminal is still blank

Post by mightyohm »

Can you describe or provide a picture of how you are using two FTDI interfaces? I'm not sure why this is necessary.

From your posts it sounds like you are trying to solve two problems at once:

1. communications between your PC and the serial port pins you soldered to the router PCB
2. communications over a usb-serial adapter on the router's USB port

I would try to solve the communications issue with the serial port pins on the router PCB working before playing with /dev/usb/tts/0. You should be seeing boot messages when the router first powers up and you should be able to bring up a login prompt. This should require 115200 baud, 8N1, no handshaking.

Have you tried richms's suggestion of doing a loopback test - connecting tx and rx of your PC's serial adapter together - to see if you can see the typed characters on your PC echo back?
bola
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Joined: Fri Sep 04, 2009 4:01 am

Re: No serial connection, terminal is still blank

Post by bola »

thx for helping.
i use the ftdi because my soldered pins on the board doesn't work. now i use the ftdi over usb and after a while of testing with stty the serial connections is fine.
Lar
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Joined: Fri Feb 05, 2010 9:16 pm

Re: No serial connection, terminal is still blank

Post by Lar »

I'm also having problems connecting to the terminal. I'm using the FTDI TTL-232R-3V3 USB-->serial connector. If I touch the yellow and orange leads on the connector, I can echo my inputs in hyperterminal. My hyperterminal settings are 115200 baud/8 data bits/Parity: none/1 Stop bit/Flow Control: None. I've tried both Auto Detect and TTY for the terminal emulation. I get nothing in the terminal window. My voltmeter shows 3.3v between the first and 4th pin. I've burned up two 520GU boards already. I've only got one left. Is there anything left for me to try?
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mightyohm
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Re: No serial connection, terminal is still blank

Post by mightyohm »

Yikes. Can you post some pics of your headers and solder joints and point out which pin of the serial adapter you are connecting to which pin on the router?

If you're pretty confident in your soldering job (doublecheck all the pins for shorts and bridges), then you can always try swapping the TX/RX lines to see if you have them reversed. This is probably the most common mistake.
Lar
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Joined: Fri Feb 05, 2010 9:16 pm

Re: No serial connection, terminal is still blank

Post by Lar »

OK, here's the back of the board Image
and here's the front, with the connector plugged in.
Image

As you can see, I connected black/yellow/orange to the GND/TX/RX connectors. I tried swapping the yellow and orange leads, but that had no effect.

I have little to no faith in my ability to solder.

Do you have any recommendations on how to verify that my soldering job is actually connecting to something? I can't think of anything else, since (1) the terminal program and the serial<-->USB connector seem to work when I touch the tx and rx wires in the serial<-->USB connector, (2) I've direct-connected to the Asus via Ethernet, so it works.

Is there anything you can think of that I can do to test this, without redoing the soldering? I suspect that if I have to remove and reattach the connector, I'll burn this last one out too.

Thanks,
Larry
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