Hello All,
I restart a discussion that I had here few time ago with 15KHz on RPI4B.
Since I started to try it with the 5.26, I get no screen or if i get it’s not the good resolution and not no exploitable at all.
I used to do it under RPI3B+ and I works like a charm with : https://github.com/recalbox/recalbox-os/wiki/Connect-your-recalbox-to-a-CRT-with-HDMI-(EN). You must the kernel in /boot/config.txt kernel=zImage (RecalBox by
kernel=boot/linux
initramfs boot/initrd.gz
But under RPI4B it isn’t the same story and I used this for my investigation : https://www.retrorgb.com/rpi240p.html (it seems to work under retropie for RPI4B).
So my config.txt (in French) becomes for RPI4B -> HDMI-VGA (UGREEN) connection with a JammaSD card to 15KHz CRT:
#Définition de l résolution du mode custom DMT 87 HDMI pour la résolution des jeux
hdmi_cvt=1920 240 60 1 1 0 0
#Ignore le EDID de votre TV (le CRT peut envoyer de mauvaises informations)
hdmi_ignore_edid=0xa5000080
#Force le mode d’encodage des pixels, 2 correspond a Full RGB
hdmi_pixel_encoding=2
#Désactive le safe mode au boot du raspberry pi
avoid_safe_mode=1
#Ne pas désactiver l’overscan
disable_overscan=0
#Evite les interférences de l’adaptateur en boostant le signal HDMI
config_hdmi_boost=4
#Force le son sur HDMI
hdmi_drive=2
#Selectionne le groupe HDMI CEA
hdmi_group=2
#Résolution CEA 6 = 480 interlaced
hdmi_mode=87
#Kernel utilisé
kernel=boot/linux
initramfs boot/initrd.gz
#Utiliser le mode HDMI même si aucun câble n’est connecé
hdmi_force_hotplug=1
#paramètres mémoire
gpu_mem_256=128
gpu_mem_512=256
gpu_mem_1024=512
#Paramètrelié a l’audio
dtparam=audio=on
#Permet de temporiser le boot
display stack
dtoverlay=vc4-kms-v3d-pi4,noaudio
There are some discussion about paramters like :
hdmi_group = 2
hdmi_mode = 87
(working but stupid resolution of splash image and ES)
instead of :
hdmi_group = 1
hdmi_mode = 8
(Not good resolution of splash image and nothing under ES)
To have I good splash image I must put :
hdmi_group = 1
hdmi_mode = 6
(good splash image but black screen under ES)
If someone have an idea ?
Thx ;-)
Stéphane
