405 lines from Raspberry Pi 5

[Mike Watterson]

I had a quick look:
1) By default the TV on HD chops edges off. Set TV to "Full" instead of 16:9.
2) By default the Pi has no composite at all.

You open \boot in Filemanager as Administrator and edit \boot\firmware\config.txt and add / edit various commands. I need to read up it.

3) with appropriate settings it does either NTSC or PAL in 4:3 mode. Sidepanels become inaccessible (these are my custom creation), and the top & bottom ones are a bit chopped (I customised the standard top bar and put workspaces, notifications, date and tasks on the bottom places bar. Both auto hide).

Mysteriously though there are two HDMI that can do 4K, enabling the PAL composite with commands in config.txt disabled both HDMI ports. Only the one beside USB-C power has audio and full signalling. On first attempt the TV briefly indicated NTSC 3.58.

the config.txt needed
dtoverlay=vc4-fkms-v3d,composite=1

Not dtoverlay=vc4-kms-v3d,composite=1

It may or may not need "enable_tvout=1"

You have to reboot to have changes. Save a copy of the original config.txt and a copy of each version that works.

There is a way to automatically have HDMI if a prearranged ID is detected and otherwise have composite. Not sure why it has NO HDMI when there are two, when composite is enabled.

The 405 line and 819 line modes are enabled by a Kernel module (.ko file) from here https://github.com/raspberrypi/linux/pull/5867 It might be just for pi 5, or it might work on pi4, or be adaptable.

There may also be another way on Ubuntu Mate ARM64 using settings in one of the config files for X. The official Raspberry Pi OS uses the Wayland system instead of X and IMO Wayland isn't even Beta. Loads of things don't work on Wayland. Redhat (owned by IBM) is driving Wayland. It's like the politics of Unity Desktop (scrapped in 2017).

I'm running Ubuntu Mate ARM64. If I mess up I can edit the SD card files on my laptop or workstation as they both run Linux Mint. Without a 405 monitor, or if your 405 mode is broken you can only fix it by editing the SD card on a different Linux box. Mac and Windows can't read/write ext4 format filesystem, unless someone has a driver. I do have ext2 on my old XP laptop.

I've also a backup of the Pi SD card.




So I need to read the manual.

[Mike Watterson]

Not too difficult to install. I think it is an update.  I just followed the instructions in that thread I linked to in the first post. Some knowledge of Linux and Pi would be desirable.

Composite on the Pi5 is a 2 pin header. Which is left blank.

It's an experimental optional kernel update via a module.

Great you have it going. I'll bow out as I have no 405 TV or monitor and what I have is a Pi 4B, not a Pi5.

Now can you run a USB DVB-T stick and play that out on the composite?

I have one working as SDR and DTT inc HD on my Android tablet flawlessly. Better than it managed on my old XP laptop! It's an oldish one now but does 24MHz to 1.8 GHz.

I've also got a Technomate HDMI (HD) to DVB-T H.264 V4 modulator sitting on the desk and I note it can do 6MHz instead of 8MHz channel and 60MHz to 69.9 MHz is now allocated "Broadband" transmission on the Comreg Amateur licence. Maybe a 420 MHz down converter unless there is VHF hack?

[Mike Watterson]

Frank, is it pure mono 405 or has it got a mad flavour of NTSC color?

[`FRANK.C]

Now can you run a USB DVB-T stick and play that out on the composite?

I don't know as I haven't one. But I expect it should.

There is no audio out on the Pi 5. I think the easiest solution to that is a USB sound card.

Frank

[`FRANK.C]

Frank, is it pure mono 405 or has it got a mad flavour of NTSC color?

As far as I can tell it is pure mono 405.

[ppppenguin]

I'm impressed.

[Nick]

Now can you run a USB DVB-T stick and play that out on the composite?

There is no audio out on the Pi 5. I think the easiest solution to that is a USB sound card.

You can use a USB sound card, like the UGREEN one, or an I2S audio hat from IQaudIO (now owned by RPi) e.g. their DAC+ or DigiAMP+, or similar devices from others.

[Mike Watterson]

I think I paid €6 each for two generic USB audio sticks. One drives headphones quite well and has volume buttons and mic mute. The other has no buttons and isn't quite loud enough on headphones. Both are stereo but claim to be 5.1 and 7.1
I got them to test Voice View via an OTG adaptor on a Kindle PW3. They work on Linux, Windows and Android; just plug them in.

Likely the Ugreen one is fine. I've some Ugreen stuff and it all works fine.

[Mike Watterson]

I'm impressed.

Certainly handier than the Trident ISA VGA card that I piggy backed an adaptor on and then poked magic numbers into registers to get 625 lines on DOS only maybe 1994.

[chriswood]

Great work Frank, if I could make a request for us lesser mortals, it would be very useful if when you finish your testing and debugging that you could do a list of working hardware and a build script we could follow to reproduce your work.