Re: LCDd Command/Display Latency

On Jun 13, 2012, at 1:38 PM, Martin T Jones wrote:

> On 13/06/12 16:16, 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
> This is from code converted from the libusb-0.1 version which is based on the picoLCD example code from mini-box, I'm not sure if it ever worked as the device does not appear to have an alternate interface setting. Perhaps the code should be removed, does anyone have any information on this? It should be safe to ignore the error report.
>> picolcd: Key repeat: delay 300, interval 200
> Success, you have libusb-1.0. 
>> (null): flush threshold to small - disabled
> This is warning about a LIRC configuration parameter "LircFlushThreshold" and can be ignored unless you want to get the IR receiver working.

I think I saw this error because I patched stable.  When I checked out and compiled HEAD the error went away.

Thank you and cheers!

Caylan

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