Fix: Distorted ili9486 display with Pi4

KM6LYW Radio

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Jun 26, 2026, 6:02:35 PM (2 days ago) Jun 26

to DigiPi

Duane noticed some distortion (horizontal banding) when using the waveshare ili9486 gpio display, specifically with DigiPi 2.1 and a Pi4. No banding is noticed when using a Pi5. I don't know if it's a new kernel "feature," but it's easily fixed by underclocking the i2c serial port on the Pi4.

Click Shell

password: raspberry

sudo remount

sudo nano direwatch.py

sudo nano digibanner.py

Around line 140, edit the spi.max_speed_hz from 48000000 to 34000000

elif displaytype == 'ili9486':
## Largest ili9486 display, no buttons
from spidev import SpiDev
import ILI9486 as ili9486
spi = SpiDev(0,0)
spi.mode = 0b10
spi.max_speed_hz = 48000000
disp = ili9486.ILI9486(
spi=spi,
rst=25,
dc=24,
origin=ili9486.Origin.LOWER_RIGHT
).begin()
disp.invert()

if it helps,

-craig

KM6LYW

Craig

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Jun 27, 2026, 10:54:53 AM (yesterday) Jun 27

to DigiPi

Issue isolated to the last Linux kernel update - if and only if you have a Pi4 and an ili9486
display (pi5 is fine), run these to commands in the Shell to regress the Linux kernel from
build 75 to build 47 and fix however the Linux kernel developers broke the SPI bus this
time.

sudo remount
sudo rpi-update 6d1da66

best,
-craig
KM6LYW

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Craig

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Jun 27, 2026, 6:07:51 PM (22 hours ago) Jun 27

to DigiPi

alternatively putting "force_turbo=1" in /boot/firmware/config.txt also solves
the ili9486/Pi4 problem on DigiPi 2.1. Kernel regression is not required.

for those of you playing along at home,