RASP-PiTFT-PLUS-FAQ
How do I automatically boot to X windows on the PiTFT?
Check out the 2.8" resistive PiTFT FAQ for an answer to this common question.
How can I bring up X on the HDMI/TV monitor?
Use the fb0 framebuffer when you want to display stuff on the HDMI/TV display, for example:
FRAMEBUFFER=/dev/fb0 startx
will use the HDMI/TV framebuffer for X windows instead of the PiTFT
That doesn't work! I can't get X on HDMI!
If both
FRAMEBUFFER=/dev/fb0 startx &
and
FRAMEBUFFER=/dev/fb1 startx &
wind up showing the GUI on your PiTFT, enter the following instruction from the command line:
sudo mv /usr/share/X11/xorg.conf.d/99-fbturbo.conf ~
I'm tring to run startx and I get FATAL: Module g2d_23 not found.
I'm tring to run startx and I get FATAL: Module g2d_23 not found.
don't forget you have to remove the turbo file!
sudo mv /usr/share/X11/xorg.conf.d/99-fbturbo.conf ~
I want better performance and faster updates!
I want better performance and faster updates!
You can also change the SPI frequency (overclock the display) by editing /etc/modprobe.d/adafruit.conf and changing the options line to:
options fbtft_device name=adafruitrt35 rotate=90 frequency=64000000 fps=30
here's the thing, the Pi only supports a fixed number of SPI frequencies. So tweaking the number a little won't do anything. The kernel will round the number to the closest value. You will always get frequencies that are 250MHz divided by an even number. Here's the only SPI frequencies this kernel supports.
- 15,625,000 (a.k.a 16000000 = 16 MHz)
- 17,857,142 (a.k.a. 18000000 = 18 MHz)
- 20,833,333 (a.k.a 21000000 = 21 MHz)
- 25,000,000 (= 25 MHz)
- 31,250,000 (a.k.a 32000000 = 32MHz)
- 41,666,666 (a.k.a 42000000 = 42MHz)
- 62,500,000 (a.k.a 62000000 = 62MHz)
So if you put in 48000000 for the speed, you won't actually get 48MHz, you'll actually only get about 42MHz because it gets rounded down. We tested this display nicely with 32MHz and we suggest that, but you can put in 42MHz and it will update a bit faster
You can tweak fps (frames per second) from 20 to 60 and frequency up to 42MHz for tradeoffs in performance and speed. Reboot after each edit to make sure the settings are loaded properly. There's a trade off that if you ask for higher FPS you're going to load the kernel more because it's trying to keep the display updated. You can try 62MHz SPI but you may find the image corrupted so, again, tradeoffs! :)
== How can I take screenshots of the display?
We took the screenshots for this tutorial with fbgrab
wget http://fbgrab.monells.se/fbgrab-1.2.tar.gz tar -zxvf fbgrab*gz cd fbgrab/ make ./fbgrab screenshot.png
Crédit: AdaFruit Industries www.adafruit.com
Source: Adafruit PiTFT 3.5" Touch Screen for Raspberry Pi
Créé par LadyAda pour AdaFruit Industries.
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Traduit avec l'autorisation d'AdaFruit Industries - Translated with the permission from Adafruit Industries - www.adafruit.com