Arduino USB compatibility with Linux

Question

I've been working on an Arduino project that needs to communicate with a (Debian) Linux NAS via USB.

It communicates perfectly reliably with a Windows terminal.

The communication with Linux is quite bad.

Here's my test application for this communication:

void setup(void) {
  Serial.begin(9600, SERIAL_8N1);
}

void loop(void) {
  do {
    Serial.println("1234567890");

    delay(1000);
  } while (true);
}

OSEPP Nano Arduino to Windows: With the OSEPP Nano Arduino, the communication looks like this with Windows:

1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
(forever, ok)

OSEPP Nano Arduino to Linux on QNAP NAS: With the OSEPP Nano Arduino, the communication looks like this with Linux on an QNAP NAS:

[~] # busybox stty -F /dev/ttyUSB0 cs8 9600 opost -ixon -ixoff -cstopb -parenb
[~] # screen /dev/ttyUSB0 –fn
/var/run/utmp: No such file or directory
15
  59
    1351159113
              51115353579779
                            9
                             79111137311371
                                           11131131359
                                                      11579
                                                           11711359
                                                                   7139
                                                                       357
                                                                          35
                                                                            3130577917931359
            39
              913717117
                       31
                         1313315791113579
                                         133
                                            373

The fact that even numbers almost never appear should be a clue to this problem. I selected different serial parameters in both the Arduino program and also the Linux command but was only able to make it much, much worse (by "worse", I mean no characters being received correctly).

OSEPP ATMega2560 Arduino to Linux on QNAP NAS: This looked useful at first but it didn't work for long.

[~] # busybox stty -F /dev/ttyUSB0 cs8 9600 opost -ixon -ixoff -cstopb -parenb
[~] # screen /dev/ttyUSB0 –fn
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
1234567890
CC�������CC�����C�������CC�Æ���CC�

I tried it a few times with surprisingly similar (not identical) results.

Arduino Duemilanove:

[~] # busybox stty -F /dev/ttyUSB0 cs8 9600 opost -ixon -ixoff -cstopb -parenb
[~] # screen /dev/ttyUSB0 –fn
/var/run/utmp: No such file or directory
   1713
       371
          3579
              137557
                    5379
                        359599
                              371591311533609
                                             597
                                                3579

                                                    1391913
                                                           15359
                                                                16813579
                                                                        15
                                                                          715715379
   11375
        551135
              7
               135513311993
                           51791357
                                   15959
                                        1111919
                                               113

Arduino Lilypad Similar results to Nano & Duemilanove.

Question: Does anyone know why this would be happening? I'd prefer to use the "Nano" Arduino since this project only needs a few I/O lines anything larger would be an over-kill.

Is the Arduino USB implementation incompatible with Linux in some way?

Thank you for any insights you can give!

You are *CORRECT*! A system daemon(?) ups_yec has been harvesting characters from the port. Thank you for your help! I had expected two processes couldn't open the same port simultaneously and assumed that this was impossible. — X-Ray, Apr 19 '17 at 03:06
@IgnacioVazquez-Abrams: Can you drop that into an answer; I'd like to mark yours as correct. Thanks! — X-Ray, Oct 22 '17 at 19:56

score 0 · Accepted Answer · answered Oct 22 '17 at 20:12

0

Linux does not prevent multiple processes from opening a serial port, and if more than one of them reads from the port then the other processes will miss any such data read. Verify that no other processes have the serial port open.

answered Oct 22 '17 at 20:12

Ignacio Vazquez-Abrams

776,304
153
1,341
1,358

Arduino USB compatibility with Linux

1 Answers1