Kontron KTAM3874-pITX - Manual (Page 80)

KTD-S0057-I Page 76 Linux® Programming Examples (DebianTM)
KTAM3874/pITX Software Guide
or with (transmit part shortened, 'lo' implies 'Local Loopback')
# cat /proc/net/dev
Inter-| Receive | Transmit
face | bytes packets errs drop fifo frame compr. multicast |bytes packets ..
lo: ??? ??? 0 0 0 0 0 0 ??? ??? ....
can0: 0 0 0 0 0 0 0 0 32 4 ....
can1: 32 4 0 0 0 0 0 0 0 0 ....
eth0: 0 0 0 0 0 0 0 0 0 0 ....
eth1: 0 0 0 0 0 0 0 0 0 0 ....
The socket interface offers an REC(EI)V(E)_OWN_MSGS option which does not work properly. The call of the
following routine has no effect.
int enable_own_msgs (void)
{
int own_msgs = 1;
return setsockopt (skt, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS, &own_msgs, sizeof (own_msgs));
}
After entering some commands this option is still available.
sudo ifconfig can0 down
sudo ip link set can0 type can loopback on
sudo ip link set can0 up type can bitrate 125000
Now you can expand/change the previous example (extract):
#define DELAY_TIME 100 /* 100 us */
#define MAX_LOOPS 10000 /* Overall 1 second */
int detect_can_frame (void)
{
struct sockaddr_can addr;
struct can_frame frame;
socklen_t skt_len = sizeof (addr);
if (recvfrom (skt, &frame, sizeof (struct can_frame), MSG_DONTWAIT | MSG_PEEK,
(struct sockaddr *) &addr, &skt_len) < 0)
return -1;
if (frame.can_dlc > 0)
return 0;
return -1;
}
int main (void)
{
int i, data_len;
char name [MAX_NAME_LEN];
unsigned char data [MAX_CAN_LEN];