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stty -F /dev/ttyUSB0

Started by Johann Klammer January 6, 2020
stty -F /dev/ttyUSB0
speed 0 baud; line = 0;
min = 1; time = 0;
-brkint -icrnl -imaxbel
-opost
-isig -icanon -iexten -echo

(something is wrong)

stty -F /dev/ttyUSB0 ispeed 38400
stty: /dev/ttyUSB0: unable to perform all requested operations

But if I give an obv wrong value it doesn't complain.
stty -F /dev/ttyUSB0 ispeed 3840


The dongle is a
FTDI Chip
TTL-232R-5V
USB to TTL Serial Cable(5.0V)-1.8m (2419945 at Farnell)

On Linux kernel Version 3.14.15

I guess since the're the monopolist 
they don't have to produce working hardware anymore.

And yes, I've read the crap about read write access on stackoverflow. 
I am in the plugdev group and it's read/writable for plugdev.

Oh, and scoping the output shows that the actual rate is at least 1MBaud
(the narrowest pulses are around 1uS wide.)


On 01/06/2020 01:33 PM, Johann Klammer wrote:
> Oh, and scoping the output shows that the actual rate is at least 1MBaud > (the narrowest pulses are around 1uS wide.) > >
ok. seems it's not the actual number that matters, but the number of invocations. It's some internal state that changes. $ stty -F /dev/ttyUSB0 ispeed 38400 stty: /dev/ttyUSB0: unable to perform all requested operations $ stty -F /dev/ttyUSB0 ispeed 38400 (this one succeeds)
On 01/06/2020 02:13 PM, Johann Klammer wrote:
> $ stty -F /dev/ttyUSB0 ispeed 38400 > stty: /dev/ttyUSB0: unable to perform all requested operations > $ stty -F /dev/ttyUSB0 ispeed 38400 > (this one succeeds) > >
may have been a user error. $ stty -F /dev/ttyUSB0 38400 works at once. I did scope the output again and observed a tau of 23 uS. (=baud rate err of 0.11) Is this too much? Because I still can't get the uC to respond..
On 01/07/2020 09:08 AM, Johann Klammer wrote:
> > I did scope the output again and observed a tau of 23 uS. > (=baud rate err of 0.11) Is this too much? > Because I still can't get the uC to respond.. > >
Nah user error again. is closer to 25uS...