Re: [Ftdi-usb-sio-devel] latency on serial port

[Bill R. <bil...@gm...>]

Have a look at this:

http://www.tldp.org/HOWTO/Serial-Programming-HOWTO/index.html

You are probably setup to do 0.1s timeout when reading the port which is the
default.

you need to set  VMIN/VTIME properly.




On Wed, Jun 23, 2010 at 4:57 PM, Tao Jin <jin...@gm...> wrote:

> Dear all,http://www.tldp.org/HOWTO/Serial-Programming-HOWTO/index.html
>
> I am trying to get my laptop running Ubuntu to communicate with a
> sensor through serial interface.  I used usb-to-serial adapter to
> connect the laptop and sensor serial RX/TX pins.  I observed a long
> latency when I do a one-byte serial echo test, around 10ms.
>
> I googled a bit, and seems a lot of people had the same issue. someone
> said setserial /dev/ttyS* low_latency can get the serial device work
> in low latency mode, with higher CPU load.  I tried, that doesn't work
> for me.
>
> Anyone here know about this latency issue on serial link?  Could you
> please provide some guidance to resolve this issue?
>
> Thanks a lot in advance!
>
> jintao
>
>
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