Thanks. I looked my code again, which is modified from example
cross-link.c. The section looks like:
...
irq_time = rx_event.rxpend_timestamp;
read = rt_dev_read(read_fd, &write_time, sz);
if (read == sz) {
read_time = rt_timer_read();
printf("%3d |%16llu |%16llu |%16llu\n", nr,
irq_time - write_time,
read_time - irq_time,
read_time - write_time);
nr++;
} else if (read < 0 ) {
printf(RTASK_PREFIX "error on rt_dev_read, code %s\n",
strerror(-err)); <<<<<<<===========
break;
} else {
printf(RTASK_PREFIX "only %d / %d byte received \n",
read, sz);
break;
}
...
I guess I should change the strerror(-err) to strerror(-read). If I do
that, I some
times get a " code input/output error". That is better. What can cause
input/output error? I get my serial port in that state consistently
when I
finish running my GPS program. I can reset it to a usable serial port
again by remove and re-load xeno-16550A module. But setserial -G can't
see anything unusual. Could it be some unclosed serial port?
My simple code is attached.
Thanks,
Everett
On Sat, Jun 12, 2010 at 5:31 PM, Gilles Chanteperdrix
<[email protected]> wrote:
> Everett Wang wrote:
>> Hi,
>>
>> I am developing a real time programming using xenomai, RTDM. When
>> I try to read serial port, I sometimes get this message:
>>
>> error on rt_dev_read, code Success
>>
>> I checked my program and found that when rt_dev_read returns a
>> negative number, this message is printed. What does this error message
>> mean? It seems that my port is open when I tried to read from it.
>
> It means that you are probably using errno, and since rt_dev_read does
> not set errno, you get "Success" as error message instead of the real
> error message. If you want to print the real error message, you should
> use strerror(-rc) where rc is the return code of rt_dev_read.
>
> But of course, I am just guessing here, seeing your test code would help
> more.
>
>
> --
> Gilles.
>
/*
* gps.c
* Read gps device periodically, compute delay and jittering
*/
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <sys/mman.h>
#include <native/task.h>
#include <native/timer.h>
#include <rtdm/rtserial.h>
#define MAIN_PREFIX "main : "
#define STASK_PREFIX "gps_task: "
#define GPS_FILE "rtser0"
#define STATE_FILE_OPENED 1
#define STATE_TASK_CREATED 2
#define SSIZE 450
int gps_fd = -1;
unsigned int gps_state = 0;
/* --s-ms-us-ns */
RTIME gps_task_period_ns = 100000000llu;
RT_TASK gps_task;
RTIME trigger_time;
static const struct rtser_config gps_config = {
.config_mask = 0xFFFF,
.baud_rate = 115200,
.parity = RTSER_DEF_PARITY,
.data_bits = RTSER_DEF_BITS,
.stop_bits = RTSER_DEF_STOPB,
.handshake = RTSER_DEF_HAND,
.fifo_depth = RTSER_DEF_FIFO_DEPTH,
.rx_timeout = 40000000, /* 40 ms */
.tx_timeout = RTSER_DEF_TIMEOUT,
.event_timeout = 100000000, /* 0.1 s */
.timestamp_history = RTSER_RX_TIMESTAMP_HISTORY,
.event_mask = RTSER_EVENT_RXPEND,
};
static int close_file( int fd, char *name)
{
int err, i=0;
do {
i++;
err = rt_dev_close(fd);
switch (err) {
case -EAGAIN:
printf(MAIN_PREFIX "%s -> EAGAIN (%d times)\n",
name, i);
rt_task_sleep(50000); /* wait 50us */
break;
case 0:
printf(MAIN_PREFIX "%s -> closed\n", name);
break;
default:
printf(MAIN_PREFIX "%s -> %s\n", name,
strerror(-err));
break;
}
} while (err == -EAGAIN && i < 10);
return err;
}
void cleanup_all(void)
{
if (gps_state & STATE_FILE_OPENED) {
close_file(gps_fd, GPS_FILE " (gps)");
gps_state &= ~STATE_FILE_OPENED;
}
if (gps_state & STATE_TASK_CREATED) {
printf(MAIN_PREFIX "delete gps_task\n");
rt_task_delete(&gps_task);
gps_state &= ~STATE_TASK_CREATED;
}
}
void catch_signal(int sig)
{
cleanup_all();
printf(MAIN_PREFIX "exit\n");
return;
}
void gps_task_proc(void *arg)
{
int err, nr = 0;
ssize_t read = 0;
char sdata[SSIZE];
ssize_t ss = SSIZE*sizeof(char);
RTIME irq_time = 0;
RTIME read_time = 0;
RTIME last_time = 0;
struct rtser_event rx_event;
while (1) {
/* waiting for event */
err = rt_dev_ioctl(gps_fd, RTSER_RTIOC_WAIT_EVENT, &rx_event);
if (err) {
printf(STASK_PREFIX
"error on RTSER_RTIOC_WAIT_EVENT, %s\n",
strerror(-err));
if (err == -ETIMEDOUT)
continue;
break;
}
irq_time = rx_event.rxpend_timestamp;
read = rt_dev_read(gps_fd, sdata, ss);
if (read >= 0) {
read_time = rt_timer_read();
printf(STASK_PREFIX "%3d | %3d | %16llu\n", nr, read,
irq_time - last_time);
/**
printf(STASK_PREFIX "%3d | %3d | %16llu\n", nr, read,
read_time - irq_time);
for(i=0;i<read;i++)
printf("%x ", sdata[i]);
**/
printf("\n");
} else {
printf(STASK_PREFIX "error on rt_dev_read, code %s\n",
strerror(-read));
break;
}
last_time = irq_time;
nr++;
}
if ((gps_state & STATE_FILE_OPENED) &&
close_file(gps_fd, GPS_FILE " (gps)") == 0)
gps_state &= ~STATE_FILE_OPENED;
printf(STASK_PREFIX "exit\n");
}
int main(int argc, char* argv[])
{
int err = 0;
signal(SIGTERM, catch_signal);
signal(SIGINT, catch_signal);
/* no memory-swapping for this programm */
mlockall(MCL_CURRENT | MCL_FUTURE);
/* open rtser0 */
gps_fd = rt_dev_open( GPS_FILE, 0);
if (gps_fd < 0) {
printf(MAIN_PREFIX "can't open %s (gps), %s\n", GPS_FILE,
strerror(-gps_fd));
goto error;
}
gps_state |= STATE_FILE_OPENED;
printf(MAIN_PREFIX "gps-file opened\n");
/* writing gps-config */
err = rt_dev_ioctl(gps_fd, RTSER_RTIOC_SET_CONFIG, &gps_config);
if (err) {
printf(MAIN_PREFIX "error while RTSER_RTIOC_SET_CONFIG, %s\n",
strerror(-err));
goto error;
}
printf(MAIN_PREFIX "gps-config written\n");
/* create gps_task */
err = rt_task_create(&gps_task, "gps_task", 0, 50, 0);
if (err) {
printf(MAIN_PREFIX "failed to create gps_task, %s\n",
strerror(-err));
goto error;
}
gps_state |= STATE_TASK_CREATED;
printf(MAIN_PREFIX "gps-task created\n");
/* start gps_task */
printf(MAIN_PREFIX "starting gps-task\n");
err = rt_task_start(&gps_task, &gps_task_proc, NULL);
if (err) {
printf(MAIN_PREFIX "failed to start gps_task, %s\n",
strerror(-err));
goto error;
}
pause();
return 0;
error:
cleanup_all();
return err;
}
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