Hi. I have digged through my problem with the serial console and it seems that the TTY layer is calling the tty_driver.write function with parameter count=0x00 although the buffer contains a 0x0a. If I check for this 0x0a, send it to the serial port and return 1 (for on char sent) it works. But I don't why count is 0x00. It does not make sense and I have not found such a special check in any other driver. Does anybody have an idea what might go wrong here? best regards -- Andre Messerschmidt Application Engineer Infineon Technologies AG