Jonatan Magnusson napsal(a):
Hi
I can't figure out how to use ftdi_read_data with a timeout ... ?
Previously I've set a latency time of 1 and then repeat the call to
ftdi_read_data 750 times to achieve the timeout i need, but that is
*hardly* optimal, and also it doesn't give an exact timeout.
I see there is a usb_read_timeout variable in the ftdi-context, but it
is set to 5000, and still i get an immediate return from ftdi_read_data
if there is no data available. I've tried to increase it to 100000 with
the same result.
Is it possible?
Regards,
Jonatan Magnusson
Hi Jonatan,
I use my own wrapper around ftdi_read_data. It returns immediately when
error occur or any amount of data is read. Timeout should be measured
with good precision.
Lada
int my_ftdi_read(struct sconn *sconn, void *data, size_t len, int
timeout_ms){
int ret;
struct timeval start, stop;
int usec, sec;
gettimeofday(&start, NULL);
while(1){
ret = ftdi_read_data(sconn->ftdi, data, len);
if (ret) break;
gettimeofday(&stop, NULL);
usec = stop.tv_usec - start.tv_usec;
sec = stop.tv_sec - start.tv_sec;
if (usec<0) usec+=1000000,sec--;
if (sec>timeout_ms/1000) break;
if (usec/1000>timeout_ms) break;
usleep(1000);
}
return ret;
}
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