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mschu

Member

Registered: 2009-03-13

Posts: 16

Website

Serial connection with minicom/gtkterm

Hi,

I'm trying to get a serial connection working using minicom on a 2.6.32-ARCH kernel. Therefor, I have short-curcuited pins 2 and 3 (RX and TX) for testing purposes. Works perfectly on Windows, so no hardware issue.

On Arch however, no data is sent or received. Gtkterm tells me there is an I/O error for ttyS0 to ttyS4. A quick Google search turned up nothing of interest. My user is added to the group uucp. Running as root does not change a thing.

Any suggestions? Did I miss a modprobe or something?

Regards,
mschu

Last edited by mschu (2010-01-09 11:37:07)

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,808

Re: Serial connection with minicom/gtkterm

You seem to be on the correct track.  I use serial ports all the time using the tools you listed.

Two things to look at.  First, the obvious -- Did you turn off hardware handshake? 

Second,  What kind of serial port are you using?  My arch machine instantiates ttyS0 through ttyS3 in the ISA address space (0x2f8, 0x3f8, 0x2e8, 0x3f8), even though I have no hardware at those addresses. 

On this laptop, I get asynchronous serial ports using a USB adapter.  Those show up on my machine starting at /dev/ttyUSB0

In summary, check that your ttyS0 - ttyS3 are mapped to real hardware.  You stated your machine has a /dev/ttys4.  That may be a real serial port.  Check your syslog for clues as to how the ports were mapped.

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mschu

Member

Registered: 2009-03-13

Posts: 16

Website

Re: Serial connection with minicom/gtkterm

Thanks for your answer. Mentioning ttyS4 was a typo (only 4 ports in /dev).

# setserial -g /dev/ttyS0
/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4

Which I think should be the correct port since Windows lists COM1 I/O at 03f8-03ff. ttyS3 is also listed IRQ: 4, but I don't think that's a problem since it seems to be no real device.

What do you mean by turning off hardware handshake? Sorry, I'm pretty new to this

And as for ttyUSB, I'm thinking about buying an USB to serial adaptor (would make things easier), but for now I'm working on an antiquated machine.

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,808

Re: Serial connection with minicom/gtkterm

As to Hardware handshake.

In GtkTerm, it is controlled by the Configuration Dialog (Configuration->Port)
Ensure the 'Flow Control' drop down is set to 'None'.  If it is set to 'RTS/CTS', the hardware will wait for the 'Ready to Send' to be asserted before sending data, and will de-assert the 'Clear to Send' signal when it is not ready for incoming data.  Xon/Xoff  transmits control characters to the sending device telling it to stop and start the stream.

Minicom call these 'Hardware Flow Control' and 'Software Flow Control'  Ctrl-A Z, -> O [Configure Minicom] -> Serial Port Setup -> Options E and F.

See if that works.  If not, let me know and I'll see what else I can do.

---

Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

mschu

Member

Registered: 2009-03-13

Posts: 16

Website

Re: Serial connection with minicom/gtkterm

Flow Control was already off.