Re: LCDd Command/Display Latency

On 13/06/12 22:59, Caylan Van Larson wrote:
> The speed I'm seeing with libusb-1.0 is definitely faster.  One out of 
> every 20 commands I send are displayed immediately.  However, most of 
> the time the display lags about .5 seconds, up to one second later. 
>  This lack of real-time response makes a user-interface difficult to 
> use.  I've tested my code and it is definitely in the display (not in 
> the key press).
>
> *Jun 13 16:55:23 coposdev04 LCDd: picolcd: USB input call-back key*
> *Jun 13 16:55:23 coposdev04 LCDd: Driver [picolcd] generated keystroke F3*
> *Jun 13 16:55:23 coposdev04 LCDd: picolcd: USB input call-back key*
> Jun 13 16:55:24 coposdev04 LCDd: output states changed
>
> The first 3 log entries above are instant.  The last one takes, quite 
> literally, one second.
Logging with 1 second resolution means differences may be up to a second 
out.
>
> LCD Client Configuration
>
> screen_add picolcd
> screen_set picolcd -priority foreground -heartbeat off -backlight on
> client_add_key -exclusively F1
> client_add_key -exclusively F2
> client_add_key -exclusively F3
> client_add_key -exclusively F4
> client_add_key -exclusively F5
> client_add_key -exclusively Left
> client_add_key -exclusively Up
> client_add_key -exclusively Down
> client_add_key -exclusively Right
> client_add_key -exclusively Enter
> client_add_key -exclusively Plus
> client_add_key -exclusively Minus
> widget_add picolcd line1 string
> widget_add picolcd line2 string
> widget_set picolcd line1 1 1 "Testing Line 1"
> widget_set picolcd line2 1 2 "Testing Line 2"
>
> Is there a way to tighten the main.c loop by way of main.h constants? 
>  I understand that tightening the loop is at the expense of CPU 
> cycles... how fast can I reasonably push it?
>
>> /* You should be able to modify the following freqencies... */
>> #define RENDER_FREQ 8
>> /* We want 8 frames per second */
>> #define PROCESS_FREQ 32
>> /* And 32 times per second processing of messages and keypresses. */
>> #define MAX_RENDER_LAG_FRAMES 16
>> /* Allow the rendering strokes to lag behind this many frames.
>>  * More lag will not be corrected, but will cause slow-down. */
>> #define TIME_UNIT (1e6/RENDER_FREQ)
>> /* Variable from stone age, still used a lot.  */
>
> p.s.  Here is a little gem that, in my opinion, is extremely graceful 
> and wonderful news for the TCP haters.
>
>>   exec 0<$LCDPIPE.in
>>   exec 1<>$LCDPIPE.out
>>   socat STDIO,ignoreeof TCP4:localhost:13666
>
> :)  Cheers!
>
> (and Thank you),
>
> Caylan

My system is complied with a higher process frequency (#define 
PROCESS_FREQ 100) which is needed to handle the IR receiver data in time 
but I don't remember a problem at the standard value.

I've just done a quick test and the slowest (client_set -name example) 
is just over 30ms.

martin@Ace:~$ socat -vlu STDIO,ignoreeof TCP4:LiFi.local:13666 2>picoLCD.log

 > 2012/06/14 14:45:54.881604  length=6 from=0 to=5
hello
< 2012/06/14 14:45:54.889096  length=73 from=0 to=72
connect LCDproc 0.5dev protocol 0.3 lcd wid 20 hgt 2 cellwid 5 cellhgt 8
 > 2012/06/14 14:46:21.853583  length=25 from=6 to=30
client_set -name example
< 2012/06/14 14:46:21.884362  length=8 from=73 to=80
success
 > 2012/06/14 14:46:32.133078  length=19 from=31 to=49
screen_add example
< 2012/06/14 14:46:32.137076  length=8 from=81 to=88
success
 > 2012/06/14 14:46:47.861075  length=27 from=50 to=76
client_add_key  -shared F1
< 2012/06/14 14:46:47.864711  length=8 from=89 to=96
success
 > 2012/06/14 14:47:12.741589  length=38 from=77 to=114
widget_add example exampleTitle title
< 2012/06/14 14:47:12.747946  length=8 from=97 to=104
success
 > 2012/06/14 14:47:20.717590  length=48 from=115 to=162
widget_set example exampleTitle "Example Title"
< 2012/06/14 14:47:20.736064  length=8 from=105 to=112
success
 > 2012/06/14 14:47:46.509084  length=27 from=163 to=189
widget_add example i1 icon
< 2012/06/14 14:47:46.522206  length=8 from=113 to=120
success
 > 2012/06/14 14:47:58.929076  length=31 from=190 to=220
widget_set example i1 1 2 prev
< 2012/06/14 14:47:58.933163  length=8 from=121 to=128
success
< 2012/06/14 14:48:15.196001  length=15 from=129 to=143
listen example
 > 2012/06/14 14:53:16.309597  length=32 from=221 to=252
widget_add example line1 string
< 2012/06/14 14:53:16.314173  length=8 from=144 to=151
success
 > 2012/06/14 14:53:26.605096  length=32 from=253 to=284
widget_add example line2 string
< 2012/06/14 14:53:26.634674  length=8 from=152 to=159
success
 > 2012/06/14 14:53:33.693094  length=46 from=285 to=330
widget_set example line1 1 1 "Testing Line 1"
< 2012/06/14 14:53:33.696917  length=8 from=160 to=167
success
 > 2012/06/14 14:53:39.429598  length=46 from=331 to=376
widget_set example line2 1 2 "Testing Line 2"
< 2012/06/14 14:53:39.436049  length=8 from=168 to=175
success

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