[SOLVED] A20-Lime2 no output on LCD after change_display

[fivuf]

Hi,

I recently  bought  an A20-Lime2 board with preloaded Debian microSD card  and a LCD display 10TS
The first time it boot up and show the display on hdmi perfectly.
I wanted to change the display on the LCD with the script change_display* but after a reboot there was no output anywhere and apparently no network neither.
I tried to burn the microSD with dd and the a20-lime2_mainline_uboot_sunxi_kernel_3.4.103_jessie_NAND_rel_9.img.

I boot up the board but no outup on hdmi (and of course not on lcd neither).

I tried the microSD on another A20-Lime2 board and same problem.
The 2 leds (red and green) are on. I can't detect it on the network (the leds on the ethernet port are off).
I can't detect it with USB-OTG. It doesn't ping and I can't connect it with SSH.


What could I do from here ?

[LubOlimex]

Test with another image: https://www.olimex.com/wiki/images/3/39/A20-lime2_debian_3.4.90_release_2.torrent

Make sure that you first extract the images.

If the problem persists, most likely the dd command that you use has some improper extra parameters or settings. Try the simplest command possible: dd if=IMAGE_NAME.img of=/dev/sdX

Best regards,
Lub/OLIMEX

[fivuf]

I made some progress.

Now with the new image on the microSD I can detect the board on the network and connect it through ssh.

I executed the script change_display.sh and choose the 10.3" (I have this https://www.olimex.com/Products/OLinuXino/LCD/LCD-OLinuXino-10TS/open-source-hardware).

But after a reboot I don't have anything displayed. I typed startx with ssh and it started without any error but I don't have any image. (And even without an X session I should have the tty displayed).

The touchscreen is powered with a 5V supply with another for the board. The LCD is connected to the board by this https://www.olimex.com/Products/Components/Cables/CABLE-40-40-10CM/. I verified that the cable was indeed connected to the lcd_con pins and to the lcd_lime2.


xrandr return:   can't open display

[fivuf]

help please, what sould I do ?
What can I test ?

thanks

[LubOlimex]

There is a good chance that the cable is reversed despite using the correct connectors. Also if powering the display from external power supply - make sure that the jumper at the back of the display is set to the proper position (there is a power jumper that has to be moved if the display gets powered from its power jack; by default the jumper is set in power from the LCD cable position).

Are you logged as root when executing the script? Make sure you are user root, not user olimex.

Can you test with serial connection to the board (instead of SSH)?

Best regards,
Lub/OLIMEX

[fivuf]

I changed the jumper to the proper position. Before that it was indeed in LCD cable position.
I'm wondering now if 5V from the board is sufficient for the LCD 10TS without another supply.

The script change_display was executed by root.

I cannot get my pc to detect the serial connection with usb-otg. But I never connected something by serial so maybe I'm not doing things correctly.

<sup>$ dmesg | grep tty

[    0.000000] console [tty0] enabled
[    5.398343] systemd[1]: Starting system-getty.slice.
[    5.398397] systemd[1]: Created slice system-getty.slice.</sup>


It's possible that the cable is reversed.


Right now it is in the next position:
The little piece of the connector of the board is turn to the extern.
The little piece of the connector of the LCD is turned to the inside.
(little piece is this https://libre-depanne.tk/wp-content/uploads/2017/03/piece.jpeg , I don't if there is another name)
Here is an image of the situation:

https://libre-depanne.tk/wp-content/uploads/2017/03/olimex.jpeg

[LubOlimex]

Yeah, the cable is reversed. It should look like that: https://drive.google.com/open?id=0B7WHuNCASY8cWnNJN3pXOXcyZ2c - notice the red stripe indicating first pin and the lack of bump at the part over the LIME2 board.

The display can be powered by the board if you are using a good external power supply (capable of providing at least 10W). Yet, if you have the option to split the 5V power supply and power both the board and the display, probably you should do it - less current flowing through the LIME2 board means less stress, less noise and less heat.

Best regards,
Lub/OLIMEX

[fivuf]

It is working now that I replaced the LCD cable in the right position.

Thanks a lot

You made a consumer happy who will certainly recommend you

Have a good day.