Hi, Thanks for Dmitri and Greg's responses.
Today I tried thoroughly many different baud rates (4800/9600/ 19200/38400/ 57600/115200/230400), but none of them worked. However, I noticed that when I switched from a high baud to a lower one (say from 230400 to 57600), I might see some garbage from my minicom screen. Does that tell anything? Also, is it normal that I don't see the file /proc/tty/driver/usb-serial? Thanks! Clement On 10 Sep 2002, Dmitri wrote: > On Tue, 2002-09-10 at 20:39, LEE, Yui-wah (Clement) wrote: > > > When running the command "setserial /dev/usb/ttyUSB0", I got the error > > "Invalid Argument". (Strace shown that it was an ioctl() failed with > > EINVAL). > > This alone is not all that dangerous. Not all serial drivers support all > serial ioctls (or all combinations of parameters). The driver is > supposed to reject everything that it can't do, and that appears to be > the case. > > > When running minicom, I got no response from the modem in > > the phone (I was using the speeds of 57600 and 230400 and various > > other speeds). However, in some occasions I did see some garbage > > echoed back (this happened when I switched from 230400 to 57600 baud > > rate). > > a) High baud rates are hard to implement without a custom crystal. The > divider becomes so small that you start getting high clock skew within > the frame time. Refrain from anything above 38.4 kbps. > > b) The FTDI chip does not tell anyone (on its serial side) what baud > rate is set. If the modem hardware connected to it can't properly sense > the baud rate then it won't work. > > My guess is that the FT8U232AM is just fine, but the modem can't figure > out what it is getting from the USB-Serial converter. Maybe you are > expected to work on a fixed baud rate; maybe there should be some > synchronization sequence (like CR few times)... > > Dmitri > > ------------------------------------------------------- In remembrance www.osdn.com/911/ _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
