Faster LCD Touchscreen


#1

OK, the time has come to ask you for some help if anyone has done it better…
We need to make the UI of the LCD more responsive as it is very slow at the moment.

The actual problem is the browser rendering the screen changes on HABpanel. We are not sure if this requires momentarily more CPU or more memory (or both).
If you use your phone app or your laptop’s browser to change, say, the heating setpoint, you will instantly see the change on the LCD too. But if the input is FROM the LCD then it is slow (1.5-2sec)
If you run the same SD card from a Raspberry 3, of course you have no delays but using a Pi3 will make the project bigger (bigger PSU too), more expensive and will produce much more heat that will affect the temperature readings.
If anyone knows or uses some tricks, please share.
Prerequisites:

  • Use OpenHAB (as it enables numerous integrations with external systems)
    Optional:
  • Use HABPanel as it allow people to easily customise the UI to their needs

#2

So far we have tried (apart from Chromium), epiphany and Midori as alternative browsers. None produced any significant change…
While OpenHAB was running we loaded a very very very simplified HTML file with buttons and some javascript interacting with the page elements and the response is great (as expected) with all browsers.


#3

Any reason not to try Firefox?


#4

Have you seen improvement with Firefox?


#5

Hey there,

Have you tried upping baud rate and lowering resolution?

https://www.raspberrypi.org/forums/viewtopic.php?p=1356449


#6

I just checked and the latest driver provided from manufacturer does not support the suggested solution:

hdmi_cvt 320 240 60 6 0 0 0

On the other hand I just noticed that the new driver on our latest Stretch distro (new image ready and will be uploaded in 2 days) is about 30% faster and more responsive! Lets see what will people say!


#7

Would a hdmi setting affect the LCD? I thought it was connected via i2c.
I am interested to know what driver exactly was sped up!


#8

Yes it is I2C. The image is “converted” into digital logic sent over the I2C in a serial form.
Enabling or disabling the HDMI does not affect the CPU load but the GPU which is not involved in the I2C business.