Re: LCDd Command/Display Latency

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

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