Configurating the serial port

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Re: Configurating the serial port

Postby Tapani » Tue Oct 08, 2013 3:29 am

jwinius wrote:Okay, I found out what was going on: the serial port has no hardware flow control (RTS/CTS). As soon as I disabled this on my client machine, then I could get into the Wandboard via its serial port with no problem at all.

The issue affects both the Ubuntu image for the Wandboard Solo, available from this site, and the Debian setup that I'm using, the HowTo for which can be found at http://eewiki.net/display/linuxonarm/Wandboard.

Is this simply because somebody forgot to enable hardware flow control in the Linux kernel configuration for the Wandboard, or because of a bug, or because the Wandboard simply does not support this feature?

Thanks,

Jaap

That someone (very likely me) very likely thought that "Since debug console does not require or support RTS/CTS, it should not be enabled".
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Re: Configurating the serial port

Postby jwinius » Thu Oct 10, 2013 3:41 pm

That someone (very likely me) very likely thought that "Since debug console does not require or support RTS/CTS, it should not be enabled".


Then please don't think of it simply as a debug console: it's a serial port first and foremost and the software should allow it to be used to the fullest extent of its capabilities even if RTS/CTS is disabled initially, e.g. with a script:

stty -F /dev/ttymxc0 -crtscts

Later on, users no longer making use of the debug console could choose to modify or disable this script.

When I received my first Wandboard, I installed Debian and immediately accessed the device using SSH. I only noticed later on that the serial port was configured as a debug console and the last thing I learned was that it wasn't using hardware flow control (which prevented me from interacting with it).

My plan had been to use the Wandboard's serial port to connect to a serial device; a small program running on the Wandboard would monitor the serial port and write any output to a file on the network. When I couldn't get RTS/CTS working on the port I eventually decided to use an RS232-USB converter instead. For now at least.

Thanks,

Jaap
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Re: Configurating the serial port

Postby meritil » Fri Dec 12, 2014 9:30 am

Hi guys,

i need to enable ctrscts on /dev/ttymxc0

stty doesn't work

how can i do?


thank you very much.
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Re: Configurating the serial port

Postby Tapani » Thu Dec 25, 2014 8:06 am

You might be able to force it in the kernel source, but stty should be the easiest...
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Re: Configurating the serial port

Postby AmandaSmith » Fri Dec 22, 2017 11:45 am

I've took a brief look at the code. It seems to me that instead of adding the inverter, you can modify the software to invert the logic within the code, by modifying one line. Swap the operators in line 48 (4 modifications highlighted):
enable ? (gpio[GFPSEL3] &= ~0x0000003F) : (gpio[GFPSEL3] |= ~0x0000003F);

-
http://streamhash.com/guide-live-streaming-equipment/
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