Input Lag LK204-7T-1U

LK/ELK/VK/PK/OK/MX/GLK/EGLK/GVK/GLT Series

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mwagner
LCD?
Posts: 2
Joined: Fri Sep 07, 2018 1:03 am

Input Lag LK204-7T-1U

Post by mwagner » Fri Sep 07, 2018 1:12 am

Hello Matrix Orbital Team,

i need help with button input from LK204-7T-1U USB-Serial to a CentOS virtual machine. I used the C++ Input/Output example on your website and altered it to fit for linux. I edited the polling to be able to show in real time when pressing a button, showing me which button is pressed. The problem i'm having is that it works the first time maybe even the second, but when exiting (closing the lcd) and recompiling and starting it again, it simply doesnt work at all. It seems like something is on sleep or blocking the transmission. Could you maybe provide me with information on how to correctly setting up the serial port on linux to get real time input? I even executed the command: "setserial /dev/<tty_name> low_latency" to minimize the latency. If you need further information please tell me.

Greetings

mwagner
LCD?
Posts: 2
Joined: Fri Sep 07, 2018 1:03 am

Re: Input Lag LK204-7T-1U

Post by mwagner » Fri Sep 07, 2018 1:58 am

UPDATE
I just figured out, that the method PollKeyPress(key_pressed) returns -1 when no inputs are recognized. Can someone tell me why it returns -1?
Auto Transmit Key Presses is turned off, so it should only return 0 if no button is pressed and 1 if a button is pressed.

Daniel Divino
Matrix Orbital
Matrix Orbital
Posts: 177
Joined: Thu Sep 24, 2015 9:38 am

Re: Input Lag LK204-7T-1U

Post by Daniel Divino » Mon Sep 10, 2018 4:37 pm

Hi Mwagner,

I apologize for the delay in response. We have a Linux appnote that may be referenced when creating applications on Linux. The appnote is developed for an LK162-7T display, but you can still take a look at how the communication port is created.

You can download our Alphanumeric C Library Appnote here: https://matrixorbital.ca/c-library

Also, If you could provide some of your code, we may be able to test it for you here.

Thanks,
Daniel
Daniel Divino
Technical Support
Matrix Orbital

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