LCD connection with Beagle board on GPIO without CAP.

General Discussion
1

I used beagle board black , in that i run image" bone-debian-10.3-iot-armhf-2020-04-06-4gb.img". As AM335x have LCD Interface Display Driver (LIDD) Controller, i want to use LCD 800*480 on GPIO pin without cap. can anyone give solution how to configure device tree for this.

2

On your BBB, have a look in /opt/source/bb.org-overlays/src/arm
Here you will find many overlays that config the LCD interface.

From a quick grep of the files, have a look at the following.
Of course you may well need to change the timings to suit your panel.
Some of those may also configure a touchscreen or not as the case may be.

BB-BONE-4D5C-01-00A1.dts
BB-BONE-4D5N-01-00A1.dts
BB-BONE-4D5R-01-00A1.dts
BB-BONE-4D7C-01-00A1.dts
BB-BONE-4D7N-01-00A1.dts
BB-BONE-4D7R-01-00A1.dts
BB-BONE-LCD7-01-00A2.dts
BB-BONE-LCD7-01-00A3.dts
BB-BONE-NH7C-01-A0.dts
BBORG_DISPLAY70-00A2.dts
BB-VIEW-LCD7-01-00A0.dts
GHI-DB-NH5C-00A0.dts
GHI-LCD-00A0.dts
GHI-TH-NH7C-00A0.dts
3

Thank you for your replay, I am new in linux , can you give me solution of below question .

  1. It is LCD cap base .dts file ?
  2. can you give steps , that what kind of change that i need to do in device tree file, by taking any example?
4

I’d go the other way, does your LCD have a datasheet? or part number, we need magic numbers from the manufacture…

Regards,

5

Well that’s potentially quite a long and complicated post.

Are you using a touchscreen ? Are you controlling a backlight ?

Have a look at both BB-BONE-4D5C-01-00A1.dts and GHI-LCD-00A0.dts

The first configures both a backlight and a touchscreen. The second just an LCD display, no backlight or touchscreen.

Depending on how many lcd data lines you need (both the abpve use lcd_data0-15) you may need to configure the extra pins.

You will then need to make sure the info in panel-info and display-timings match your lcd panel.

You best bet is to check the LCD overlays and if you are lucky one will match the display you are using. At least a couple of the files I looked at mention a name in comments.

If memory servers me, you might also need to modify the bootargs passed from uboot to the kernel.

6

LCD number is AT0701N94. i attched data shett, please check it.
AT070TN94.pdf (798.5 KB)

7

thank you for your replay , i attched one pdf for batter convoy problem , in this case 1 ) it is working fine
case 2) that i need to do.
DocScanner Jul 7, 2023 12-28 PM.pdf (173.1 KB)

please give solution if you have idea how to do this .

8

ok if you use the GHI-LCD-00A0.dts as a base you will need to enable lcd_data16-23.
They are commented out in the dts. There are two places that you need to uncomment these. It is pretty obvious.

Most of the timings should work, however you need to change the hback-porch and vback-porch settings in the display-timings section. If you check the datasheet, these are the HS blanking and VS blanking values. Not sure about the vsync and hsync values. I suggest you try with what is already set.

9

hi,
I have “ti-processor-sdk-linux-am335x-evm-08.02.00.24-Linux-x86-Install.bin” i successfully build it and get image in SD card and Beagel board is boot up .
When i connect HDMI i get output on both 7 inch GPIO dispaly that i connected and HDMI display .
Now i want to run only GPIO LCD without connecting HDMI , SO can you give me step by step solution . Please also mention in which file and what type of change i need to do in device tree.