Re: Linux serial port dropping bytes

On Wed, 02 Apr 2008 22:33:00 +0100, John Devereux
<jdREMOVE@xxxxxxxxxxxxxxxxxx> wrote:

Grant Edwards <grante@xxxxxxxx> writes:

On 2008-04-02, Anton Erasmus <nobody@xxxxxxxxxxxxxxxx> wrote:

This turned out to be 5x faster than with the onboard UARTs where one
had to check the FIFO not empty flag every time.
On a 50MHz ARM9 it took about 25us per 16 characters having to do it
the way CBFalconer described it, while it only took about 5us per 16
characters where one could read how many chars were in the Rx FIFO.

There are a lot of micro-controllers out there with horribly
designed UARTs in them. One I've fought with recently is the
in the Samsung S3C4530. Half of the features don't work at
all. Half of the stuff that does work are useless because
whoever specified/designed the UART had never actually done any
serial communications only had a vague understanding of how
things like UARTs and FIFOs are used. For example, it has
FIFOs, but there's no way to flush them. It also has "hardware
flow control", but it doesn't work in a way that can be used
with any other UART on the planet.

Everything with a "industry standard '550 uart" is horrible.

I agree. The worst part is that it seems that it is becoming more
prevalent. The Philips LPC2000 series has got these horrible UARTs,
which have been badly implemented as well. If one needs 8 uarts or
more, then it seems that only '550 UARTs are available these days.
It is amazing how probably the worst UART ever designed, has become
the "Industry Standard".

Regards
Anton Erasmus

.

Relevant Pages

  • Re: ISR16550
    ... Does it support FIFO? ... external QUART) that I am using with CE 4.2. ... serial device driver, all 6 ports work. ... on-processor UARTS work properly - IO on the QUART ports cause the following ...
    (microsoft.public.windowsce.platbuilder)
  • Re: Linux serial port dropping bytes
    ... characters where one could read how many chars were in the Rx FIFO. ... things like UARTs and FIFOs are used. ... Yep - also the Sharp ARMs and Analog devices ADUC7k ... series ARMs. ...
    (comp.arch.embedded)
  • Re: Linux serial port dropping bytes
    ... the way CBFalconer described it, while it only took about 5us per 16 ... characters where one could read how many chars were in the Rx FIFO. ... things like UARTs and FIFOs are used. ...
    (comp.arch.embedded)