A recent project was delivered to me with a problem with its LCD screen. In the process of testing it I wanted to generate a composite video signal. After looking at some ideas involving Arduino and resistor dividers I came across some examples of raspberry Pi testcards, specifically RPI - ATV

 

I had an original Pi model B which has an RCA socket with composite out so that was ideal for my task.

sony-rasp-pi.jpg

To get the testcard to work I downloaded a suitable picture and added my text to it. I then installed the python script into the /home/pi/atv folder and added my image and a dummy sound file into the /home/pi/atv/images and /home/pi/atv/sounds folders.

I tweaked the python script not to use the internal generator and also to load the first image.

 

#don't always start with internal picture
internalPicture = false
loadimage("1")

 

To get the generator to start up automatically, I had tried using rc.local but that did not seem to work. I had a bit of help from fvan who suggested cron would work.

 

To add the cron job I ran the following which prompted me to pick and editor to edit the file.

 

sudo crontab -e

 

I added in my task to run on reboot.

 

@reboot python /home/pi/atv/atv3.py

 

For testing I plugged in a phono cable from the pi to my TV and booted it up using a USB battery box.

TestingTheTestCard.jpg