Android & UART

GautierD

Hi everyone and thanks for this board that helped a lot.

I'm a proud new owner of LeMaker Guitar Rev B running Android.

Now, I have some issues regarding the communication through UART with a Raspberry Pi running Raspbian.

On Raspbian, UART is working (tested with an Arduino, too many eval boards on one table!).

I can't get the pins 8 & 10 to work.

I tried to install WiringLMK but it doesn't work on Android. I tried sysfs, but couldn't find the proper tty related to those PINs.

I don't want to use the DEBUG UART on the 6 pins next to Ethernet.

Can I have a bit of help or something that could guide me ?

More precisions :

I have a Lemaker Guitar Package A : Basic Developer including :
- Lemaker Guitar + Lemaker Guitar Base Board Rev. B
- Android 5.1.1 with Kernel 3.10.37

SSH is working if needed.

Thanks everyone!

Best regards,
Gautier

tony_zhang

http://wiki.lemaker.org/Use_Java_to_control_GPIO_on_Android  here is something about how to use GPIO, SPI, I2C on Guitar under Android. But it do not tell how to use UART.

I do not know if you can change code to enable the UART.
Here is the source code for the JNI library:
https://github.com/LeMaker/LMK.JAVAIO

GautierD

Hi tony_zhang, and thank you for your answer

I actually have been through all the wiki I think.

I don't want to use Java because at the end, this code will be a kernel module in Android as a driver for a UART Touchscreen that I am developing during my internship.

In fact, the link you just gave me will work in an app, and I want it to work in the whole Android system. I may not have been clear about that point.

Anyway, thanks for your answer, I really appreciate that.

Gautier

tony_zhang

OK. To make the pin8 & 10 work, please first check the sex file in the source code:
https://github.com/ChrisP-Androi ... aker/sys_config.fex
It seems it do not open the part function.

GautierD

Hi tony,

Thanks for your answer.

How can I use this file ? It is not present in the source code in android-actions on your github (https://github.com/LeMaker/android-actions).

Thanks again for your answer.

GautierD

Here what I found so far :

I was wondering why is it enabled on linux and not android.

In /proc/device-tree :

serial@b0120000 is "okay" for Linux but "disabled" on Android.
But in .dts, both of them are okay :

https://github.com/LeMaker/andro ... aker_guitar_bbb.dts (line 404).

GautierD

For those who are looking for it - and since Lemaker has not answered any of my calls and emails regarding this issue.

The device tree compiled on the prebuilt Android image provided by Lemaker disabled the ttyS0 - UART0.
(I still don't know why...).

In order to solve it, you need to change the device-tree.
It is located at /misc/kernel.dtb.

You need to uncompile it, export it (using device-tree-compiler, ie. dtc).
And then change the "disabled" to "okay" behind serial@0b120000.
Then compile it again and send it back to /misc (you might need to remount the partition in read-write, don't forget to remount in read-only afterwards).

Hope it helps.

tony_zhang

GautierD replied at May 27, 2016 08:19
Hi tony,

Thanks for your answer.

OK. Sorry, you use the Guitar plateform. So you need modify the DTS file of the guitar. I do not know the exact file name of the guitar dts for android.

GautierD

Yes, as I said just above you, I finally found that.

Thank you for your (late) help.

May I know why Android is installed on eMMC by default ?

tony_zhang

http://wiki.lemaker.org/Use_Java_to_control_GPIO_on_Android#UART