From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?ISO-8859-1?Q?Heinz=2DJ=FCrgen?= Oertel <oe@emtas.de>
Subject: Re: detect auto baud rate on can bus in linux driver.
Date: Tue, 29 Apr 2014 14:47:19 +0200
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References: <53590FB6.6090707@tataelxsi.co.in> <20140427094418.GB28319@griso.site> <20140427180135.GB21176@vandijck-laurijssen.be>
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To: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
Cc: Ratheendran <ba.rsrajeshwaran@tataelxsi.co.in>, John Whitmore <arigead@gmail.com>, linux-can@vger.kernel.org


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Am Sonntag, 27. April 2014, 20:01:35 schrieb Kurt Van Dijck:
>=20
> Autobaud is, IMO, a userspace thing.
> The principle has been explained, and with iproute2 & candump piping =
into
> grep or wc, you could even make a shell script for that.


In can4linux it can be done in user space, like

int do_autobaud(can_fd)
{
int bitrate[] =3D {10, 20,  50, 125, 250, 500, 800, 1000 , 0};
int i;
int ret;
can_statuspar_t status;

=09printf("\tswitch into listen only mode\n");=20
=09set_lomode(can_fd, 1);
=09/* for all possible bit rates */
=09for (i =3D 0; ; i++) {
=09=09if (bitrate[i] =3D=3D 0) {
=09=09=09ret =3D 0;
=09=09=09break;
=09=09}
=09=09printf("\tTry %d Kbit/s\n", bitrate[i]);
=09=09set_bitrate(can_fd, bitrate[i]);
=09=09/* wait one second */
=09=09sleep(1);
=09=09ioctl(can_fd, CAN_IOCTL_STATUS, &status);
=09=09/* printf("Rx buffer: %d\n", status.rx_buffer_used); */
=09=09if (status.rx_buffer_used > 1) {
=09=09=09printf("\t\tCould receive frames. Switch back to=20
active mode\n");
=09=09=09ret =3D bitrate[i];
=09=09=09break;
=09=09}
=09}
=09if (ret > 0) {
=09=09/* bit rate detected */
=09=09set_lomode(can_fd, 0);
=09}
=09return ret;
}


Of course the CAN controller should have a 'listen only' mode.

On a running EnergyBus it looks like:

using CAN device /dev/can1
doing auto bit rate detection now
take care that traffic is on the bus
        switch into listen only mode
        Try 10 Kbit/s
        Try 20 Kbit/s
        Try 50 Kbit/s
        Try 125 Kbit/s
        Try 250 Kbit/s
                Could receive frames. Switch back to active mode




=2D-=20

Mit freundlichen Gr=FC=DFen

    Heinz-J=FCrgen Oertel

=2D----------------------------------------------------------------------=
=2D-

emtas - your embedded solution partner
=20

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