Need help in understanding a i2c configuration effect


Peter Heß
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Hello,

 

I configured 2 armbian on sd card and the configuration of the i2c is the same in armbianEnv.txt. Plattform Olimex-Lime2 A20

 

verbosity=1
logo=disabled
console=both
disp_mode=1280x1024p50
overlay_prefix=sun7i-a20
rootdev=UUID=194e9f9a-826b-4644-9f2f-4ef388277816
rootfstype=ext4
overlays=i2c1 i2c2 uart3
usbstoragequirks=0x2537:0x1066:u,0x2537:0x1068:u

as you see, I confiugred the overlays.

 

But on one image I get:

 

#image with desktop

sudo i2cdetect -l
i2c-3   i2c             mv64xxx_i2c adapter                     I2C adapter
i2c-1   i2c             mv64xxx_i2c adapter                     I2C adapter
i2c-2   i2c             mv64xxx_i2c adapter                     I2C adapter

and booting the other image I get

 

# headless image

sudo i2cdetect -l
i2c-3   i2c             mv64xxx_i2c adapter                     I2C adapter
i2c-1   i2c             mv64xxx_i2c adapter                     I2C adapter
i2c-2   i2c             mv64xxx_i2c adapter                     I2C adapter
i2c-0   i2c             sun4i_hdmi_i2c adapter                  I2C adapter

so I get an aditional device for i2c-0.

 

I don't understand what's happening. What could cause this effect? Or better: What must happen, that the i2c-0 does not appear in the list.

One more info: The first image has a runing desktop and the second one in headless. Maybe this has something to do with the issue?

Can someone give me a pointer to understand this. Btw. both versions work perfekt:

 

i2cdetect -y 2

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 21 -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

 

i2cdetect -y 3

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f

00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 21 -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

The 0x68 is a RTC which is configured. So everything is OK, but I drives me crazy not to understand what I've done "wrong". Can someone give me a pointer?

 

Thanks for all help.

Edited by Peter Heß
typo
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Armbian is a community driven open source project. Do you like to contribute your code?

its "de" in DT. you can comment/remove

&de {
	status = "okay";
};

in dt

so the i2c hdmi adapter will not be initialized

 

or you can use aliases to define i2c buses like

 

aliases {
    i2c0 = &i2c0;
    i2c1 = &i2c1;
	i2c2 = &i2c2;
	i2c3 = &i2c3;
  };

 

so the i2c hdmi adapter will be named i2c-4 

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