In the previous post where I mentioned pivec, I glossed over the other details of setting up your PI to output 240p composite video. If you are using an old B&W TV or monochrome monitor in the US, you'll want to use 240p because the altenative 480i mode will cause very annoying flicker. It gives me a headache in just a few minutes.

The video related lines in my config.txt looks like this:

#dtoverlay=vc4-kms-v3d
sdtv_mode=16
sdtv_aspect=1
enable_tvout=1
framebuffer_width=720
franebuffer_height=224
overscan_left=16

enable_tvout=1 enables the composite video out. sdtv_mode=16 sets it to 240p. You can play with the framebuffer and overscan settings to get the picture right for your display.

Note: this setup uses the legacy PI video driver. The new driver has 240p mode, but I haven't been able to set it up with the chroma signal disabled. If I use pivec to disable it, it will reset those bits on the next screen blank. So, I won't use that driver until it supports a Mono mode with the 240p configuration.

To install pivec, run the following commands from the command line.

git clone https://github.com/racerxr650r/pivec
cd pivec
make prereqs
make boot