second com port not working

**gentoocar** · 03-05-2006, 10:48 AM

Hi Everyone,

Not sure if this is a hardware or software problem... I'm trying to use the second com port on my epia m10000. If I run 'setserial /dev/ttyS1' it detects it and shows the UART type. Then I ran 'cat /dev/hda > /dev/ttyS1' and plugged my homemade serial cable to my windows box to hopefully see some garbage scrolling past. I don't see anything. I'm pretty sure my cable is wired correctly, and the com parameters are correct (if I set up /dev/ttyS0 I can log in through the cable). Is there anything special I have to do to enable this port?

BTW I'm using LinuxBios.. not sure if that makes a difference.

**kraft** · 03-05-2006, 03:13 PM

http://www.via.com.tw/en/products/ma...ia_m/index.jsp

I don't see two serial ports on this board.
Are you sure it's not a virtual port associated with IrDa ?

**gentoocar** · 03-05-2006, 03:22 PM

It's got one - it's a header though. In that page you linked me to, if you look under "Onboard I/O Connectors", it has "1 Connector for LVDS module1 Serial port connector for a second com port" - somehow they missed a bullet and jumbled all of that onto one line.

Check out the bottom of the first post here: XM on Carputer THE GUIDE That's how I wired mine (different board, but same pin-out on the connector).

**kraft** · 03-05-2006, 03:55 PM

Ok i see, then you should suspect that something is not activated in the bios, did you checked with "dmesg | more" or had a look in the very early boot stage in the syslog to see what hardware is detected ?

**gentoocar** · 03-05-2006, 06:45 PM

dmesg gives me this:

[ 3893.729673] Serial: 8250/16550 driver $Revision: 1.90 $ 2 ports, IRQ sharing
disabled
[ 3893.738815] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[ 3893.745923] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A

So looks like the kernel does see it...

I just tried with another cable, same problem.

**kraft** · 03-06-2006, 01:33 AM

Ok with the kernel, that's a good point

Is your cable a straight cable i mean pin to pin or is it a twisted null modem cable ?
Try to reverse the tx and rx pins it won't be harmfull for the hardware and a wrong pin assignment is still possible, this could explain the situation.

**LagunaICE** · 03-06-2006, 02:15 AM

For Epia boards, you have to use VIA header cable due to some pins are mixed on pinheader comparing to Intel standart. At least I had to make cable myself.

**kraft** · 03-06-2006, 02:18 AM

It would be nice to post the pin assigment if you have it somewhere

**gentoocar** · 03-06-2006, 07:22 PM

Ok I found the problem - with LinuxBios, the port doesn't work, with the original via bios it works fine. So it wasn't my cable after all. I'll have to rethink whether I really want to use LinuxBios... the extra 2-ish seconds it saves me doesn't seem worth all the effort I've put in to it.

By the way, anybody looking for the pinout of the epia board, see XM on Carputer THE GUIDE - it's in the first post, near the end. The pin numbers correspond exactly to the DB9 pins, so pin 1 of the epia's com header goes to pin 1 of the male DB9, etc. It's also in the pdf manual on the via site.