Re: LCDd Command/Display Latency

On 13.06.2012 17:16, Caylan Larson wrote:
> On Jun 12, 2012, at 10:27 AM, Martin T Jones wrote:
>
>> On 12/06/12 00:58, Caylan Larson wrote:
>>> Hi,
>>>
>>> Is there any way to reduce the latency between submitting a command
>>> via port 13666 and updating the LCD?  I'm experiencing a 1.5 second
>>> delay in command submission and LCD display.
>>>
>>> I'm using a picolcd in an M300 case.
>>>
>>> Thank you,
>>>
>>> Caylan
>>>
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>>>   
>> You need LCDproc version 0.5.5 built with libusb version 1.0 to get
>> good response times.
>>
>> I expect pre-built versions in the distribution packages are still
>> using libusb-0.1 which makes the picoLCD driver very sluggish due to
>> a 500ms wait for key input.
>>
>> You will get the following message from LCDd if you are using the
>> picoLCD driver with libusb version 1.0.
>>
>> LCDd: picolcd: Key repeat: delay 300, interval 200
>>
>> If you do not get the above message install libusb-1.0 then obtain
>> and build the latest LCDproc, see:
>> http://lcdproc.sourceforge.net/docs/current-user.html
>>
>> I use the following configure command, you may need to change the
>> prefix and may want to omit debug.
>>
>> ./configure --enable-drivers=picolcd,lirc --prefix=/usr
>> --enable-debug --enable-lcdproc-menus
>>
>> Check the output includes the following lines:
>>
>> The picolcd driver is using the libusb-1.0 library.
>>
>> ---------------------------------------
>>
>> LCDd will be compiled with the drivers:
>>
>>    -  picolcd
>>
>> Next build using:
>>
>> make
>>
>>
>> Then test, see:
>> http://lcdproc.sourceforge.net/docs/current-user.html#running-lcdd
>>
>> Hopefully this will give you version with good response times.
>>
>> Good luck.
>>
>> Martin
>
> The CVS version of lcdproc doesn't have libusb-1.0 support for
> picolcd.so.  I was able to use the patch available
> at http://comments.gmane.org/gmane.comp.sysutils.lcdproc/13639
> (http://cache.gmane.org//gmane/comp/sysutils/lcdproc/13777-001.bin).
>  I have verified that the speed is OK.  However, there are 2 more
> lines that don't make sense to me but may be useful to another.
>
> /*picolcd: libusb_set_interface_alt_setting error -5*/
> picolcd: Key repeat: delay 300, interval 200
> /*(null): flush threshold to small - disabled*/
>
> Is this anything to worry about?
>
> Caylan
>

Hi,

CVS HEAD does contain the libusb-1.0 stuff (see
http://lcdproc.cvs.sourceforge.net/viewvc/lcdproc/lcdproc/server/drivers/picolcd.c?revision=1.24&view=markup).

a) which CVS branch did you check out? You need to use HEAD.

b) which OS are you using? This may be of interest.

Regards,
Markus