Raspberry pi driving a 4K display

Raspberry Pi’s are very nice computers. For one of my latest projects I needed to drive a 4K display and it worked fine on a Raspberry Pi 3B+. For fun I tried the same config on a Raspberry Pi zero and even that worked out. The only downside of a zero is that it has limited memory and it needs roughly 192MB for the graphics card. The downside? I was only able to get 30Hz, but for my application (static photoframe) that’s more than enough.

The config (/boot/config.txt):

disable_overscan=1

hdmi_ignore_edid=0xa5000080
hdmi_group=2
hdmi_mode=87


hdmi_timings=3840 1 48 32 80 2160 1 3 5 54 0 0 0 30 0 248832000 3
# <h_active_pixels> 3840
# <h_sync_polarity 1
# <h_front_porch> 48
# <h_sync_pulse> 32
# <h_back_porch> 80
# <v_active_lines> 2160
# <v_sync_polarity>1
# <v_front_porch>3
# <v_sync_pulse> 5
# <v_back_porch> 54
# <v_sync_offset_a> 0
# <v_sync_offset_b> 0
# <pixel_rep> 0
# <frame_rate> 30
# <interlaced> 0
# <pixel_freq> clock frequency (width*height*framerate) =248832000
# <aspect_ratio> 3=16/9

framebuffer_width=3840
framebuffer_height=2160
max_framebuffer_width=3840
max_framebuffer_height=2160

gpu_mem=192

hdmi_pixel_freq_limit=400000000

# not really required:
arm_freq=1500
gpu_freq=500