On 08.01.2011 17:32, Thorsten Godau wrote:
> So i tried to use "slcan_attach -o -s6 -c /dev/ttyUSB0" ...
(..)
> so the correct command should be "slcan_attach -c -s6 -o /dev/ttyUSB0".
(..)
> Nevertheless i can't get the bitrate changed properly with slcan_attach.
> The solution was the echo command (to be honest i tried to change the
> CAN bitrate before determining the working serial parameters):
>
> echo -e -n "C\rS6\rO\r" > /dev/ttyUSB0
Hi Thorsten,
thanks for your extensive investigation on this topic!
Currently the slcan_attach only uses the commandline options as boolean
switches to send "O\r", "C\r", "S?\r" and "s????\r" in this order:
S? -> s???? -> O -> (attach tty) -> (wait) -> (detach tty) -> C
And this works fine in the case the slcan adapter is in 'close' state at the
start of slcan_attach.
So the _order_ of the commandline has no effect on the behaviour as you tried
in the two examples in the beginning of this mail.
To fix this behaviour, i would suggest to force a close of the slcan adapter
before setting the bitrate (which is also common for other CAN
adapters/controllers). E.g. by sending
"C\rS?\r" instead of only "S?\r"
Then we would have this possible init sequence of slcan_attach:
CS? -> Cs???? -> O -> (attach tty) -> (wait) -> (detach tty) -> C
Can you try this (also attached) patch to check whether a 'close' before
setting the bitrate brings back the wanted functionality?
Index: slcan_attach.c
===================================================================
--- slcan_attach.c (Revision 1227)
+++ slcan_attach.c (Arbeitskopie)
@@ -150,12 +150,12 @@
if (waitkey || !detach) {
if (speed) {
- sprintf(buf, "S%s\r", speed);
+ sprintf(buf, "C\rS%s\r", speed);
write(fd, buf, strlen(buf));
}
if (btr) {
- sprintf(buf, "s%s\r", btr);
+ sprintf(buf, "C\rs%s\r", btr);
write(fd, buf, strlen(buf));
}
Finally your approach with the
echo -e -n "C\rS6\rO\r" > /dev/ttyUSB0
command looks also very good as it uses the standard unix idea to have simple
and clearly arranged tools for each use-case :-)
Btw. when slcan_attach provides some functionality on the commandline, it
should JUST WORK like expected ;-)
73!
Oliver (DK4AM)
Index: slcan_attach.c
===================================================================
--- slcan_attach.c (Revision 1227)
+++ slcan_attach.c (Arbeitskopie)
@@ -150,12 +150,12 @@
if (waitkey || !detach) {
if (speed) {
- sprintf(buf, "S%s\r", speed);
+ sprintf(buf, "C\rS%s\r", speed);
write(fd, buf, strlen(buf));
}
if (btr) {
- sprintf(buf, "s%s\r", btr);
+ sprintf(buf, "C\rs%s\r", btr);
write(fd, buf, strlen(buf));
}
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