Well, which kernel are you using? Type "uname -a" on the terminal.
I don't think it is a kernel issue. One thing you did not said on the
previously thread is how are you connecting the UART1 to your computer.
If the code is permanently blocking, and depending how you set up the
serial port, this means that no data is received. You need to check the
connections and remember that all those pins are 3.3V or you will burn
them...
Miguel
On 24-09-2014 08:42, Julian Gold wrote:
So I have been trying to write code to read data asynchronously from a
serial port. I have tried it with /dev/ttyO1 (using UART1), and also
with /dev/ttyUSB0 (using an FTDI USB cable in the USB port).
Here is a snippet of code. This fails on both serial ports, but in
different manners:
|
voidreadSerial(intfd )
{
fd_set readfs;
FD_ZERO(&readfs );
FD_SET(fd,&readfs );
while(1)
{
select(fd+1,&readfs,0,0,0);
if(FD_ISSET(fd,&readfs ))
{
charbuffer[32];
intn =read(fd,buffer,32);
printf(buffer );fflush(stdout );
}
}
}
|
On /dev/ttyO1, the select() call blocks permanently, with no input
being acknowledged. On /dev/ttyUSB0, the function prints EVERY OTHER
character, so if I type "connect" into my PC terminal program, I will
get either "cnet" or "onc" depending on what came before. Either way,
it appears select() is broken because if I replace this with
|
while((n=read(fd,buffer,32))>0)
{
printf(buffer);fflush(stdout);
}
|
Then I get "connect" as expected on /dev/ttyUSB0 (untried as yet on
/dev/ttyO1). This seems like a fundamental problem with the Angstrom
kernel?
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