support for non standard baud rates if tcsetattr fails

[azplanlos]

update for pull request #46 as discussed there.

Support for non standard baud rates if setting port attributes fail as fallback including error handling and notifying delegate.

Successfully tested with Junsi iCharger (CP210x chipset) at 128000 baud.

[armadsen]

I'm struggling a bit with this because non-standard baud rates are not universally supported. For example, after this change, setting the baud rate to 128000 on my Keyspan adapters seems to work. tcsetattr() fails, but the subsequent call to ioctl() doesn't return an error, so the ORSSerialPort delegate is never notified of an error. However, the baud rate is not in fact set to 128000, and there's no way for the user of ORSSerialPort to detect this programatically.

This could be worked around if it were possible to reliably read the actual baud rate of the port, but as far as I can tell, baud rates set with IOSSIOSPEED are not readable (e.g. using cfgetispeed() on the termios returned by tcgetattr()).

This is essentially the same issue that caused me to hesitate on #45. It seems like the options are:

• Continue not supporting non-standard baud rates. (Obviously I'd rather support them.)
• Thoroughly document this behavior with the caveat that it doesn't work with all USB to serial adapters/drivers and should be used with caution.
• Make support for non-standard baud rates configurable. e.g. an allowsNonStandardBaudRates property.
• Make setting a nonstandard baud rate require the use of a different property, e.g. -setNonStandardBaudRate:.
• ???

Any thoughts?

[azplanlos]

This is an issue related to OS X and Linux as discussed in various forums around the net. It seems like some 3rd party drivers (like the one I tested) are supporting these bitrates but the OS definately does not and most probably will not. For this I favour your suggestion of introducing a property for this behaviour. Most probably it should be off by default as this is what you would expect from the OS side. I vote for a allowsNonStandardBaudRates property with a default value of NO.

Andreas Zöllner
Sent with Airmail

Absender: Andrew Madsen notifications@github.commailto:notifications@github.com
Antworten: armadsen/ORSSerialPort reply@reply.github.commailto:reply@reply.github.com
Datum: 28. März 2015 at 18:20:07
Empfänger: armadsen/ORSSerialPort orsserialport@noreply.github.commailto:orsserialport@noreply.github.com
CC: Andreas Zöllner andi@go-for-fun.demailto:andi@go-for-fun.de
Betreff: Re: [ORSSerialPort] support for non standard baud rates if tcsetattr fails (#49)

I'm struggling a bit with this because non-standard baud rates are not universally supported. For example, after this change, setting the baud rate to 128000 on my Keyspan adapters seems to work. tcsetattr() fails, but the subsequent call to ioctl() doesn't return an error, so the ORSSerialPort delegate is never notified of an error. However, the baud rate is not in fact set to 128000, and there's no way for the user of ORSSerialPort to detect this programatically.

This could be worked around if it were possible to reliably read the actual baud rate of the port, but as far as I can tell, baud rates set with IOSSIOSPEED are not readable (e.g. using cfgetispeed() on the termios returned by tcgetattr()).

This is essentially the same issue that caused me to hesitate on #45#45. It seems like the options are:

• Continue not supporting non-standard baud rates. (Obviously I'd rather support them.)
• Thoroughly document this behavior with the caveat that it doesn't work with all USB to serial adapters/drivers and should be used with caution.
• Make support for non-standard baud rates configurable. e.g. an allowsNonStandardBaudRates property.
• Make setting a nonstandard baud rate require the use of a different property, e.g. -setNonStandardBaudRate:.
• ???

Any thoughts?

—
Reply to this email directly or view it on GitHubhttps://github.com//pull/49#issuecomment-87256637.

[armadsen]

Redoing this to make sure @azplanlos gets credit.

[armadsen]

OK, manually merged this into 1.8.0 in eae268b . Thanks again!

[azplanlos]

Thanks!