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So I'm trying to get a touchscreen from Chalkboard Electronics to work with my model B Raspberry Pi. The specific product I have is this 7" capacitive touchscreen which connects to the Raspberry Pi over HDMI using an HDMI-LVDS converter.

I'm using Raspbian wheezy 2012-10-28 as my operating system and the EDID file supplied by the manufacturer. My config.txt file contains:

hdmi_edid_file=1
hdmi_group=2
hdmi_mode=28
framebuffer_width=1024
framebuffer_height=600
hdmi_ignore_cec=1
hdmi_force_hotplug=1
config_hdmi_boost=4

However, I get no output on the screen. The backlight of the display lights up, Raspberry Pi's red light is on steady, green light flashes (in no particular sequence). I've also connected the Pi to a standard HDMI monitor (after disabling option for EDID) and it works fine. I've separately plugged in the touchscreen via the HDMI-LVDS converter into a Windows laptop, and the touchscreen does display output. I've also used the SD card test image used by the manufacturer - and no dice.

Are there any solutions for the display not working, or diagnostic steps I can carry out?

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1 Answer 1

up vote 2 down vote accepted

I solved this problem by adding this line to my config.txt file:

hdmi_ignore_edid=0xa5000080

Turns out that the touchscreen, to use the words used by Raspberry Pi wiki, is a "crappy Chinese" one and needs this line to work correctly.

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