Re: [Lcd4linux-devel] Time-out for picoLCD 256x64

[Michael R. <mi...@re...>]

Hi Martin,

> I had written that polling the button states using LCD::GPI(1)
> considerably slows down output on my picoLCD 256x64 and located the
> problem in this function:
> 
>    static int drv_pLG_read(unsigned char *data, int size)
>    {
>      return usb_interrupt_read(lcd, USB_ENDPOINT_IN + 1, (char *) data,
>      size, 1000);
>    }
> 
> On second thoughts, I have made the mistake to think that this function
> times out *every* time.  When a key is pressed, however, the function
> exits directly and thus only times out when no data are present for
> usb_interrupt_read().

Well, this means the picoLCD does not answer with something like "zero keys pressed", but just times out?

Sounds *a little bit* braindamaged to me ;-)

> My problem is that I don't know what time-out value should be used.  I
> have experimented a little: 1 ms is too low, while 2 ms work fine on my
> desktop.  On my embedded system, 3 ms are needed.  But what about people
> using the display with an old USB 1.0 port?  I propose 5 ms or 10 ms --
> what do you think?

I's recommend a value of 5 msec, and make it a config option within the display section


HTH, Michael

-- 
Michael Reinelt <mi...@re...>
http://home.pages.at/reinelt
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