"Pelle" == Pelle Windestam<pelle@xxxxxxxxx> writes:
Pelle> Hello, I am using libftdi to access a FTDI 2232D chip. I have two
Pelle> configurations of the 2232D, in one case it is completely
Pelle> unmodified, and in the other case it is configured to be used as
Pelle> a JTAG debug board
Pelle> (http://wiki.openmoko.org/wiki/Debug_Board_v2). In both of these
Pelle> cases one of the FTDI UARTs is connected to a RS-485 transceiver.
Pelle> I am experiencing problems with the second case, the debug
Pelle> board. If I connect the FTDI-device and try to communicate using
Pelle> libftdi, it does not work. I can successfully open the device,
Pelle> but I cannot communicate with my external device (over
Pelle> RS-485). If I print out what I read back from the serial port I
Pelle> am flooded with data containing only zeroes (nothing from the
Pelle> external device). After my application is finished, the ttyUSBx
Pelle> device has been removed from /dev.
Pelle> While troubleshooting this I discovered that if I communicate
Pelle> using /dev/ttyUSBx (open(), write(), close()) it works
Pelle> perfectly. I also discovered that if I use this method first, I
Pelle> can use the libftdi afterwards. Upon reconnection it fails again
Pelle> if I try to use libftdi first.
Pelle> I have tried this using libftdi-0.2 and libftdi from the git
Pelle> repo. Any ideas?
What OS are you using. Perhaps you can find with "strace" the failing system
call? I suspect that some prerequisite for libusb is missibg in one case.
Bye
I am using Linux 3.2.0 and 3.5.0 on two separate machines, running
debian testing. I looked at the strace output but nothing really pops
out. No systems calls that are failing. I compared the strace output
from when I run libftdi first (not working) and when I use conventional
tty access first, but they look the same.
I did some more testing and it appears that it doesn't work with the
unmodified FTDI eeprom either as I stated in my first e-mail. In both
cases I need to use /dev/ttyUSBx access first to get libftdi-access working.
//Pelle
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