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I would like to use a Raspberry Pi to generate test patterns in the composite output (for adjusting TVs, VCRs etc). I think the most convenient way would be to control it using ssh (as I may not be able to see what it is generating and do not want to connect a keyboard to it) to display various test patterns (bmp or png images) and to change the output format (color/BW, PAL/NTSC), hopefully without restarting the Pi.

Is there a way to do that?

  • From @deeluna's answer: Something you could do if you are more the hardware hacker type: instead of using ssh to control it, put a button connected to the Pi in some way to make it switch through different test patterns and a small LCD (like a 5 line LCD) to display some information based on what the pi is outputting to the given screen. It wouldn't even need a full OS, a bare-bones command-line-interface with a script that waits for input from the button and then one of the cell phone battery packs to make it power up when away from power sources. – RPiAwesomeness Mar 7 '14 at 16:09
  • My copied comment: I just need it for repairing/adjusting TVs or VCRs. Control over ssh is good enough for me and is simpler to do. When I use it I would be near a PC (for reading circuit diagrams/manuals) and power outlet, so it does not need to work from batteries. – Pentium100 Mar 7 '14 at 16:17
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you may remove X11 from your system or just disable desktop using 'raspi-config', then log in using ssh and send images directly to the framebuffer, images could be .jpg or .png files (other formats may be supported as well, but I haven't checked):

fbi -d /dev/fb0 -a *.jpg

'fbi' package can be installed using plain old 'apt-get':

sudo apt-get install fbi

TV formats are saved in config file that is most probably read only once at the boot time, so I think you'll need to reboot to change from PAL to NTSC. Or maybe someone knows the method to avoid the reboot.

  • This is the method I was going to suggest :) – einnocent Dec 29 '13 at 15:25
  • I couldn't make fbi work, but fim works OK. Thanks. – Pentium100 Jan 3 '14 at 2:44
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Something you could do if you are more the hardware hacker type:

instead of using ssh to control it, put a button connected to the Pi in some way to make it switch through different test patterns and a small LCD (like a 5 line LCD) to display some information based on what the pi is outputting through the given video out.

It wouldn't even need a full OS, just a partial one with out a GUI (unless you use it for other things.) Just a bare-bones command-line-interface with a script that waits for input from the button and then one of the cell phone battery packs to make it power up when away from power sources.

I wouldn't know about the programming side of it as I just started with a pi.

  • I just need it for repairing/adjusting TVs or VCRs. Control over ssh is good enough for me and is simpler to do. When I use it I would be near a PC (for reading circuit diagrams/manuals) and power outlet, so it does not need to work from batteries. – Pentium100 Mar 7 '14 at 14:57

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