FBTFT: model A+ with HY28B touchscreen problem - Raspberry Pi Forums

i'm trying connect 2.8" hy28b lcd model a+ pi, , having issue touch screen. x starts fine on display, whenever use touchscreen display starts glitching. looks blocks of pixels ending in random places on screen.

configured pi use display using couple of threads here.
fresh raspbian image,
sudo rpi-update
expand partition through raspi-config
sudo reboot

added /boot/config.txt:
dtoverlay=hy28b, rotate=90

replace /usr/share/x11/xorg.conf.d/99-fbturbo.conf with:

section "serverlayout"
identifier "tft"
screen 0 "screentft"
endsection

section "screen"
identifier "screentft"
monitor "monitortft"
device "devicetft"
endsection

section "monitor"
identifier "monitortft"
endsection

section "device"
identifier "devicetft"
driver "fbdev"
option "fbdev" "/dev/fb1"
endsection


here, whether configure/calibrate touch panel or not, running startx followed pressing touchscreen cause glitch badly.

seems cs0 , cs1 getting mixed up, pins aren't bridged don't think in hardware , running dmesg after boot shows touch panel driver configured spi0.1 , lcd driver spi0.0, guessing referring spi0 cs0 , spi0 cs1, doesn't seem configuration problem.

ideas might causing this?

hi , welcome forum.
known problem of these displays. being driven speeds way on specification, although of them work, of them not.
there note on suppliers 'wiki' page here :
http://www.hotmcu.com/wiki/hy28b_-_2.8% ... spberry_pi

the speed= variable tells driver how fast drive display. 36mhz (36000000) pretty nice 20 fps rate if screen acting funny, try taking down 10mhz (10000000), in fact, lcd speed can 36mhz.

mode= variable tells driver spi mode use display. mode 3 capable lcd, lcd, when touch screen, lcd display abnormal, can try spi mode=0.

did not have luck that. buy lot of these displays, specify them tested pi before send them me....

configuration page displays :
viewtopic.php?f=45&t=105797&p=765088
hope helps,
texy

raspberrypi