0

The background of this is the following: I own an Atlys FPGA board, and I am busy implementing a UART on it, because the possibilities for other diagnostics are rather limited.

I want to use a portable (on which I also run the FPGA software) as terminal for the board. The portable is from 2004, AMD x64, 1 GB of RAM, running Linux 3.2.0.4 kernel on Debian. The board contains an XR21V1410 serial to USB bridge, which is driven by the Vizzini driver (2013).

The result is that this works fine for 9600 bps. However, going to 19200 it seems that data is dropped. This happens independently of the speed at which I supply data. E.g. I can throttle the system to only send 1 char/s, or 80 chars/s, data still get dropped. I am trying to find out where the problem could occur.

The data I send is a stream of characters A..Z, followed by 0d 0a.

Diagnostics using two ways of reading /dev/ttyUSB0 give different results. With minicom, it seems that the data is garbled so that it receives control codes. I suppose that this is because minicom emulates the VT102.

Reading the device raw (cat /dev/ttyUSB0), it seems that it sometimes receives correct characters in a stream, but not always.

Does anybody have experience with usbserial and the maximum attainable data rates on Linux? That is the first cause that I would like to try to exclude.

chthon
  • 101
  • 1
  • 3
  • 1
    *"Does anybody have experience with usbserial and the maximum attainable data rates on Linux?"* -- I've used FTDI and Prolific USB-to-serial adapters for 115200 baud connections with Linux for over a decade. – sawdust Sep 21 '18 at 21:09
  • @sawdust: this was actually a usable comment, as it made me consider to think out of the box. After testing a whole lot of setups, I found out that some of the switches (or their soldering joints) don't work. So when I thought that I changed the communication speed, and setup minicom for that, the actual speed did not change. – chthon Sep 26 '18 at 13:35

0 Answers0