Raspberry Pi 3,Composite out and 240p: A brief tutorial to achieve the beautiful 320x240 in progressive scan.

With the release of a new firmware, now we are able to achieve the  output resolution over composite of 320x240 in progressive scan and forget the flickery 480i (the standard output resolution over composite).

This is the worst-quality possible solution in terms of picture quality...but i think it' s better than the flickery 480i, and the image quality, if you have a good CRT TV or Monitor (i have a JVC tm h140 pn with S-video and composite IN only) is enjoyable..at least in my honest opinion.

Then, you need:

• A Raspberry PI 3 (Pi3 is recommended for full speed, especially for psx and N64 games)
• A  A/V Composite Cable - 3.5mm to 3 x RCA  like the one in the pic below
• A CRT tv with composite IN or scart with an adapter (composite to scart) 
• Obviously a MicroSD of at least 16GB 
• HDMI cable for the firsts steps after fresh installation of Retropie.

note:  A good 2.5A PSU is recommended for the RPi3, emulation is a power demanding task and a heatsink is also recommended because the Rpi3 can reach 85-90° in full load w/o passive dissipation.

My Raspi with custom heatsink (52° in full load)

If you have all the stuff above you can start  installing  Retropie normally...

for NOW hook up your Pi at a standard LCD TV or monitor via HDMI

https://retropie.org.uk/

• once you have correctly installed you Retropie...
•  Exit Emulation Station and reach the console....

sudo apt-get install rpi-update 

then

sudo rpi-update

This installs the lastest firmware...

Now you must modify the "config.txt" file to achieve the 240p output over composite.

this file is located here:                             /boot/config.txt

to modify:                                                  sudo nano /boot/config.txt

add at the end of the file this string:          sdtv_mode=18      #this for PAL progressive Signal

    

                                                                      or

                                                                   sdtv_mode=16      #this for NTSC progressive Signal

then CTRL-X and Y for save changes  in NANO... :-)

now                                                            sudo shutdown

Now, once you have turned off your Pi, plug in the composite cable and connect your CRT TV or CRT monitor. Now your Pi's output resolution is a lovely 320x240 in progressive scan. :-) and your emulated games will be more "real"..especially compared with the flickery 480i.
The image is very stable and the scanlines are present, especially on my JVC broadcast monitor...

here some examples...