hi all,
I have been trying to get data in and out of /dev/ttyS1 for a while now without success. The setup i have is this: verdex XL6P, GPSstix and netwifimicroSD. I need to attach another external serial device (which also produce NMEA sentences, like the gps receiver) to the gumstix. As far as i understand, ttyS0 (FFUART) is used as a gumstix console, ttyS2 (STUART) is used by the gps recevier, which leaves ttyS1 (BTUART) as the only option to attach my serial device (verdex doesnt have HWUART right ?). I have built a 3-port level shifter to which I connected FFUART (GND, VCC, RX and TX pins) and BTUART (same pins as FFUART, i left untouched CTS and RTS). Through the shifter, FFUART is connected to a computer and BTUART  to the external serial device. With this setup, I was unable "cat /dev/ttyS1" after setting up the serial port parameters with stty....

so, to test ttyS1, I removed my external serial device and connected the gumstix's ttyS1 to ttyUSB0 on my computer. I disabled hardware flow control and set the line to 9600, 8, N, 1 as shown in the output below:

test@testbed:~$ stty -a -F /dev/ttyUSB0
speed 9600 baud; rows 0; columns 0; line = 0;
intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R;
werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0;
-parenb -parodd cs8 hupcl -cstopb cread clocal -crtscts
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl -ixon -ixoff -iuclc -ixany -imaxbel -iutf8
opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke

I did the same on the gumstix:
root@gumstix-custom-verdex:~$ stty -a -F /dev/ttyS1
speed 9600 baud; rows 0; columns 0;
intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;
eol2 = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W;
lnext = ^V; flush = ^O; min = 1; time = 0;
-parenb -parodd cs8 hupcl -cstopb cread clocal -crtscts
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl -ixon -ixoff
-iuclc -ixany -imaxbel
opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt
echoctl echoke

I tried sending from the gumstix to the computer:
while true; do echo "hello" > /dev/ttyS1; sleep 1; done
but "cat /dev/ttyUSB0" shows nothing

no success the other way around either....
The only clues I got:
 - the output of cat /proc/tty/driver/PXA\ serial shows some bytes  were sent but none received....
 - scoping Rx and Tx pins on my homemade level shifter shows bits are definitely sent from the computer to the gumstix, but nothing is sent from the gumstix.
Does that sound like a config problem on the gumstix ?
Things that might help:

cat /proc/tty/driver/PXA\ serial
serinfo:1.0 driver revision:
0: uart:FFUART mmio:0x40100000 irq:22 tx:25679 rx:2600 RTS|CTS|DTR|DSR|CD|RI
1: uart:BTUART mmio:0x40200000 irq:21 tx:518 rx:0
2: uart:STUART mmio:0x40700000 irq:20 tx:0 rx:0

cat /proc/gpio/GPIO4[23]
42      AF1     in      set
43      AF2     out     set


As an aside question, which process creates and maintain the terminal on ttyS0 ? even though inittab mentions it, there are no references to a getty on ttyS0 reported by ps (the only getty is on tty1), and the closest thing I found is the "console" kernel arg, but as far as i know this only dumps lines at boot time over the serial port. It doesnt create a terminal where users can login. How is this console created then ?

Cheers,
Gilles