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Monitors, HDMI and config.txt

After writing about little touchscreens for the Raspberry Pi (TinyLCD, AliExpress LCD), the official Raspberry Pi Touchscreen, now a post about HDMI monitors. I have several now and each has it pros and cons. As usual, the one you use will be dependent on the project and it is nice to have choice.

Note that there is always an extra facility to control the Raspberry Pi comfortable from behind the large screen and professional keyboard of my PC on my desk, once network is available: SSH and PuTTY for the commandline, and XRDP for the desktop for programming, see here how to use that.

These are the monitors I use with my Pi’s, connected via HDMI:

As you can see from small, 5 and 7 inch, to quite large!

Support a particular screen format

A standard HD HDMI monitor works fine on the RPi, in 1920×1080 pixels native format. But these smaller screens have lower  resolutions and the reuslting image looks bad. So every monitor for an optimal picture, requires some simple adaptations in the RPi configuration file /boot/config.txt.
For a good description of the entries in the config.txt see the Elinux site and on here the Raspberry foundation site.

First some entries to have a better understanding of, edit the file with care and reboot after changes made. It may be handy to have SSH network access, since the screen may not give a useful picture when experimenting with the settings.

 
sudo nano /boot/config.txt 

# uncomment if you get no picture on HDMI for a default "safe" mode 
#hdmi_safe=1
# uncomment if hdmi display is not detected and composite is being output
#hdmi_force_hotplug=1

# uncomment to increase signal to HDMI, if you have interference, blanking, or no display
#config_hdmi_boost=4
tvservice -d edid
edidparser edid

Study the output, determine group and mode (CEA, DMT) and add the following lines, as shown in the description for each monitor to the end of your config.txt and check all the other HDMI/SD settings not to be active!

HDMIPI

A 9 inch HDMI monitor, developed and sold via a kickstarter campaign by Alex Eames (of Raspi.tv fame, see also his RasPIO Duino product) and Cyntech (who did the actual production and shipping). Still available on Raspberry Pi webshops and from Cyntech. 1200×800, shiny acrylic case, 2x HDMI input, VGA optional. Gives sound output!
I did not add a Raspberry Pi ‘inside’ but use it as a monitor . A DIY package, mine came with broken inside panels,  some superglue overcame this invisible. My delivered driver board was broken, and replaced without problems.

Good picture, though the reflective mirroring and slight diffusing effects of the acrylic in front of the screen can be annoying in daylight. Handle with care to avoid scratches.

Nicely documented on http://hdmipi.com/.

IMG_4567 IMG_4568 IMG_4571

(yes, that is my hand holding the camera!)

# HDMIPI 1280x800 60 Hz 
hdmi_ignore_edid=0xa5000080 
hdmi_group=2 
hdmi_drive=2 
# for alternative modes get sound 
hdmi_mode=28 

7 inch HDMI VGA AV AT070TN90 800×480 lcd display

IMG_4564 IMG_4565 IMG_4562IMG_4566

Search on e.g. ebay or AliExpress or Amazon for HDMI-VGA-2AV Reversing Driver-board 7 inch AT070TN90 800×480 lcd display.

Good picture, very flexible with HDMI, VGA, and 2 AV inputs. No sound support. Comes as kit, I made with my limited skills a wooden frame.

CVT mode as explained on the Raspberry fora

hdmi_cvt= <width> <height> <framerate> <aspect> <margins> <interlace> <rb>
width        width in pixels
height       height in pixels
framerate    framerate in Hz
aspect       aspect ratio 1=4:3, 2=14:9, 3=16:9, 4=5:4, 5=16:10, 6=15:9
margins      0=margins disabled, 1=margins enabled
interlace    0=progressive, 1=interlaced
rb           0=normal, 1=reduced blanking
# 7 inch LCD Display monitor ebay 800x480 AT070TN90
#increase HDMI signal strength (just a black screen if not set!) 
config_hdmi_boost=4 
#remove black borders 
disable_overscan=1 
#set CVT as default 
hdmi_group=2 
hdmi_mode=87 
#set specific CVT mode 
hdmi_cvt 800 480 60 6 0 0 0 

LG FLATRON M197WD

I use this 19 inch  monitor as a general purpose monitor for video and audio in my lab for all its inputs: television and monitor, widescreen multiple inputs, SCART, HDMI, VGA, component, AV.
IMG_4573 IMG_4574

# LG and HD ready Philips TV DMT mode 28 1368 x 768 (which is scaled to 1200x800!) 
hdmi_group=2 
hdmi_mode=28 

Dell UltraSharp 1704FPT 17″ Flat Panel LCD Monitor

General purpose PC monitor, 1280×1024. Connected via HDMI to DVI converter.

IMG_4576 IMG_4577IMG_4582

Excellent sharp picture, though not widescreen.

#DELL DMT mode 35 1280x1024
hdmi_group=2 
hdmi_mode=35 

HP 1530 1024×768

IMG_4581 IMG_4579

Small 15 inch monitor with audio, DVI and VGA. Connected via HDMI to DVI converter. Has an analog audio input!

Excellent picture, though not widescreen.

 
# HP1530 1024x768 
DMT mode 16 
hdmi_group=2 
hdmi_mode=16 

5 inch LCD HDMI Touch Screen Display TFT LCD Panel Module 800*480

7inchtouch

See this 7 inch monitor for settings7 inch LCD screen, bought from ebay, AT070TN90

5 Inch TFT LCD Car Rear View Monitor

A very cheap ($17 including shipping) and small display. Only composite. Works fine on the Raspberry Pi all models. The console is mediocre, the desktop is not bad at all. Not recommended though, but handy to test composite and an occasional view.

IMG_4596

IMG_4595 IMG_4597

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