CAN_DEVCTL_SET_PRIO
QNX SDP8.0Devctl and Ioctl CommandsDeveloper
Set the priority for transmitted messages
Synopsis:
#include <sys/can_dcmd.h>
#define CAN_DEVCTL_SET_PRIO __DIOT(_DCMD_MISC, CAN_CMD_CODE + 5, uint32_t)
Arguments to devctl():
| Argument | Value |
|---|---|
| filedes | A file descriptor that you obtained by opening the device. This must be for a transmit mailbox (e.g., /dev/can1/tx3). |
| dcmd | CAN_DEVCTL_SET_PRIO |
| dev_data_ptr | A pointer to a uint32_t |
| n_bytes | sizeof(uint32_t) |
| dev_info_ptr | NULL |
Description:
This command sets the priority of messages for a transmit mailbox. The hardware uses these priorities to determine which CAN message to transmit first if there are multiple messages waiting to be transmitted.
Note:
Some devices use fixed priorities for the mailboxes.
For example, the first message object (i.e., the one that RX0 receives)
might have the highest priority, and the last might have the lowest.
Input:
The new priority, which must not exceed the maximum for the device (usually defined as a constant whose name is in the form board_CANMCF_TPL_MAXVAL).
Output:
None.
Example:
int ret;
uint32_t val;
if( (fd = open( "/dev/can1/tx3", O_RDWR)) == -1 )
{
printf("open of %s failed \n", devname);
exit(EXIT_FAILURE);
}
/* Get the new priority. */
val = strtoul(optarg, NULL, 0);
if(EOK != (ret = devctl(fd, CAN_DEVCTL_SET_PRIO, &val, sizeof(val), NULL)))
{
fprintf(stderr, "devctl CAN_DEVCTL_SET_PRIO: %s\n", strerror(ret));
}
See also:
devctl() in the QNX OS C Library Reference
canctl in the Utilities Reference
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