Capturing a response from the display

GTT TFT Support

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bigmaple
LCD?
Posts: 8
Joined: Tue Apr 14, 2020 5:10 am
Location: Western Pennsylvania

Capturing a response from the display

Post by bigmaple »

Hello,
In my project, I would like to be able to know when a particular screen is finished loading. To that end, I followed the advice in the post GTT Firmware Rev 2.0 capabilities, protocol manual issues in which it was suggested
f you're looking for an alternative to the Get Module command, specifically for the GTT, you might consider adding an Echo command at the end of your autoexec file. That way, once the GTT has finished booting and executing all other autoexec commands, it can echo a response of your choosing back to your host controller.
On each my screens, I added a Post Load - Custom Script action that uses the ECHO command to send a short string.

What I don't understand is how to read that ECHO from my host, so that I can proceed knowing that my screen has bee loaded. Looking at the gtt_protocol source code, I don't see anything like a "get_response" function.

Anyone know how to do this?

Raquel
Matrix Orbital
Matrix Orbital
Posts: 735
Joined: Thu Aug 19, 2004 3:37 pm
Location: MO Office

Re: Capturing a response from the display

Post by Raquel »

Hi,

Thank you for posting on the forum.

Yes, Echo is a good way to indicate to the host that the GTT has finished executing a screen.
Echo acts as a voluntary report (like touch reports) when you get a script to run it and hence does not need a "get" command.
You will need to be polling for any data coming and decipher them. For the echo:
252 255 <2 byte length> <ASCII string>

I hope this helps.
Best Regards,
Raquel
Raquel Malinis
Design and Development
Matrix Orbital

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