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JohnBeardmore
Posts: 211
Joined: Thu Nov 15, 2012 11:03 pm
Location: Derbyshire UK.
Contact: Website

Pi as public display screen

Tue Nov 08, 2016 12:30 am

I want to use the HDMI ouput of the Pi as a public display screen while being able to access the Pi for other purposes over ssh and Remote Desktop Connection.

I would like to have various static parts of the display show some graphs and logos, but most of the area should be used to show some simple numberic data using a very big font, refreshed every 15 seconds.

The numeric data comes from a process written in C++ which gets some energy data over a neywork and keeps a 15 second rolling 4 average, giving rise to one fixed point number with format %2.1f - If it would be a useful intermediate step, this data could be written to bitmap and then displayed somehow.

Somebody pointed me at Screenly OSE, but is there a simple programatic way to access the entire HDMI screen and prevent any other processes getting at it ? Or for that matter is there any other simple way to show dynamic content using the HDMI output.

Thanks, J/.
Author of oBeMS open source Building energy Management System.
Automatic Meter Reading (AMR), Building Management System (BMS),
Building Energy Management System (BEMS), Infrastructure Control System (ICS).
See: http://t4sustainability.co.uk/oBeMS/

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dividuum
Posts: 189
Joined: Sun Jun 16, 2013 1:18 pm
Location: Germany
Contact: Website

Re: Pi as public display screen

Tue Nov 08, 2016 1:24 pm

You might have a look at my tool info-beamer. It was basically created to do things like this. I've written a blog post about how to do something similar to what you requested. The basic idea is to have info-beamer running all the time and then interacting with it by either changing files (like images of graphs, that you might update from C++) or sending realtime data through TCP or UDP. Let me know you have any questions.
info-beamer hosted - A user and programmer friendly digital signage platform for the Pi: https://info-beamer.com/hosted

RpiName
Posts: 713
Joined: Sat Jul 06, 2013 3:14 am

Re: Pi as public display screen

Tue Nov 08, 2016 10:10 pm

JohnBeardmore wrote:I want to use the HDMI ouput of the Pi as a public display screen while being able to access the Pi for other purposes over ssh and Remote Desktop Connection.
See if this clip can help:
https://www.youtube.com/watch?v=wthS8TP ... e=youtu.be

For more info, see:
http://linux-projects.org

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JohnBeardmore
Posts: 211
Joined: Thu Nov 15, 2012 11:03 pm
Location: Derbyshire UK.
Contact: Website

Re: Pi as public display screen

Fri Jan 20, 2017 12:27 am

Hi folks,

Thanks for the advice. In the end for various reasons I decided to write my own thing from scratch using libx11.

Seems to be doing what I need which is basically checking for a message left in a file in /tmp every few seconds, and if it's changed, writing it on the screen in big letters.

There will still need to be a few tweaks, but the prototype is looking quite usable.

Code will be open sourced in due course as an open source energy display, but easily hacked for other applications I guess.


Cheers, J/.
Author of oBeMS open source Building energy Management System.
Automatic Meter Reading (AMR), Building Management System (BMS),
Building Energy Management System (BEMS), Infrastructure Control System (ICS).
See: http://t4sustainability.co.uk/oBeMS/

fredfs
Posts: 58
Joined: Sun Jun 07, 2015 12:22 am

Re: Pi as public display screen

Sun Mar 05, 2017 6:49 pm

I am looking for something like this.
Do you mind sharing the code?
JohnBeardmore wrote:Hi folks,

Thanks for the advice. In the end for various reasons I decided to write my own thing from scratch using libx11.

Seems to be doing what I need which is basically checking for a message left in a file in /tmp every few seconds, and if it's changed, writing it on the screen in big letters.

There will still need to be a few tweaks, but the prototype is looking quite usable.

Code will be open sourced in due course as an open source energy display, but easily hacked for other applications I guess.


Cheers, J/.

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