Serialport ignores bytes = 0x11

[atimin]

Very strange behavior! Teh serial port doesn't receive bytes which equal 0x11. I have tried to receive same package with other tool (CuteCom) and I have had success. I don't have idea what it may be...

  #Device send: [0x10][0x11][0x12]
  sp.read.unpack('c*')  #=> [16,18] 

Ruby - 1.9.3
OS. Ubuntu 12.04-amd64

[willglynn]

0x11 is XON (see http://en.wikipedia.org/wiki/Software_flow_control). Is #flow_control set to SerialPort::NONE?

[atimin]

Yes it is!

  sp.flow_control #=> 2 (SOFT)

I have added `sp.flow_control = SerialPort::NONE' in my code and I have success. Thank you!
But I think this behavior is unexpected and the flow control must be disabled by default.

[trevorms]

Here is the fix for this issue...one character was missing:

diff --git a/ext/native/posix_serialport_impl.c b/ext/native/posix_serialport_impl.c
index 11294fa..7747969 100644
--- a/ext/native/posix_serialport_impl.c
+++ b/ext/native/posix_serialport_impl.c
@@ -157,7 +157,7 @@ VALUE sp_create_impl(class, _port)

    params.c_oflag = 0;
    params.c_lflag = 0;
-   params.c_iflag &= (IXON | IXOFF | IXANY);
+   params.c_iflag &= ~(IXON | IXOFF | IXANY);
    params.c_cflag |= CLOCAL | CREAD;
    params.c_cflag &= ~HUPCL;

1. Clone this repo
2. Apply the above patch
3. gem build serialport.gemspec
4. gem install serialport-1.1.0.gem --local

[ghost]

@hparra : what do you think about this fix here?

[hparra]

I'm not entirely sure. It seems the problem is just an unexpected default setting. In that case I'm reluctant to commit the line change because it could break existing systems dependent on this gem.

I welcome @FLIPBack and @trevorms to chime in.

[trevorms]

The original line of code that does not turn off XON/XOFF flow control (params.c_iflag &= (IXON | IXOFF | IXANY);), is clearing all the other bits in the params.c_iflag variable that perhaps should not be cleared. The original line of code will ensure that all the bits are cleared except the IXON, IXOFF and IXANY bits...unless of course this was the original intention. I have used this change successfully and the default is XON/XOFF flow control is disabled.

[trevorms]

BTW...thanks for the great gem @hparra...I use it a lot in my hardware development work.

[corecode]

This looks pretty much like a bug in the original code. What will it take to fix this?