Orange Pi 3 and i2c

LuRu · April 19, 2021 at 2:31 PM

I intend to run LCDproc on an Orange Pi 3. I would like to use a display with an HD44780 controller connected via i2c.

I connected PCF8574 to OPi3 and it doesn't work. So I tried the i2cdetect utility and I see that my PCF8574 interface is not detected.

Then I inserted an SD card with the Armbian system into my device and tried the same thing (without any change of connection).

It works so my circuit is correct.

What should I do to make i2c work in LibreELEC?

**lrusak** · April 19, 2021 at 3:54 PM Official Post

It doesn't look like we include the linux driver (CONFIG_HD44780)

**jernej** · April 19, 2021 at 4:32 PM Official Post

You have to enable I2C bus in DT. Easiest way is to add overlay. I believe Armbian enables I2Cs using patch during kernel build.

Quote from lrusak

It doesn't look like we include the linux driver (CONFIG_HD44780)

That one supports only parallel interface.

LuRu · April 19, 2021 at 5:24 PM

Thank you for the advice.

Unfortunately, I have little knowledge in this regard.

I've read about overlays in the wiki, but there is only Raspberry described, no Allwinner.

I took the sun50i-h6-i2c0.dtbo file from Armbian and copied it to the /flash/overlays folder in LE.

But still no detection of the PCF8574 interface address.

How do I know the overlay is loaded?

Does it have to be allowed somewhere else?

**jernej** · April 19, 2021 at 6:40 PM Official Post

You have to add line FDTOVERLAYS /overlays/sun50i-h6-i2c0.dtbo to extlinux.conf. I'm a bit lazy regarding documentation...

LuRu · April 20, 2021 at 3:53 PM

Thank you for further advice on how to proceed.

Unfortunately, the result is still the same - no detection of the PCF8574 address.

My extlinux.conf file now looks like this:

Code

LABEL LibreELEC
  LINUX /KERNEL
  FDT /sun50i-h6-orangepi-3.dtb
  APPEND boot=UUID=2212-5002 disk=UUID=2047348e-1e45-42ca-a55a-b19a509853fa quiet console=ttyS0,115200 console=tty1
  FDTOVERLAYS /overlays/sun50i-h6-i2c0.dtbo

Is it right ?

What's next ?

**jernej** · April 20, 2021 at 4:14 PM Official Post

Quote from LuRu

Is it right ?

It is (maybe just move FTDOVERLAYS one line higher, although it shouldn't matter).

Quote from LuRu

What's next ?

Are you sure your device is connected to I2C0? H6 has 3 I2C buses, 4 if you count one for PMIC. If you sure, then I don't know...

LuRu · April 20, 2021 at 4:25 PM

I think that's right:

1) There is no other i2c port on the GPIO header

2) I have the same connection when I boot Armbian, and there it works with the command i2cdetect -y 0 (see pictures in the first post)

**jernej** · April 20, 2021 at 4:41 PM Official Post

Quote from LuRu

There is no other i2c port on the GPIO header

All three are there, just pins are named differently. I2C1 is on SPI1-MOSI and SPI1-MISO, I2C2 is on UART3-RX and UART3-TX and they lack pull ups, so yeah, you most probably use I2C0.

BTW, 0x36 is PMIC address. You are probing wrong bus. Make sure you have now 3 buses and probe all except HDMI.

LuRu · April 20, 2021 at 5:06 PM

1) In the meantime I tried to move FTDOVERLAYS one line higher and it has a big effect. LE doesn't boot - see picture - it stops like this and does nothing further (I had to return it using "cardreader edit")

2) i2cdetect -l says I have two i2c buses. See picture

**jernej** · April 20, 2021 at 5:17 PM Official Post

well, there you have it - overlay you're using isn't correct - it shouldn't freeze during boot and you should get additional i2c bus listed. What is wrong with it - I don't know. From what I can see, seems good.

LuRu · April 20, 2021 at 5:26 PM

Maybe the mistake is that I took a .dtbo file from an Armbian image (there i2c-0 works properly).

Maybe I should take it elsewhere?

LuRu · April 21, 2021 at 2:17 PM

Quote from jernej

- overlay you're using isn't correct -

Can you please specify in what sense isn't correct?

I did some other experiments. First in Armbian OS.

First I enabled all three i2c buses in armbian-config and switched my interface to i2c2.

It works again. But interestingly, there are even 5 i2c buses at the moment!

Code

root@orangepi3:~# i2cdetect -l
i2c-3    i2c           DesignWare HDMI                     I2C adapter
i2c-1    i2c           mv64xxx_i2c adapter                 I2C adapter
i2c-4    i2c           mv64xxx_i2c adapter                 I2C adapter
i2c-2    i2c           mv64xxx_i2c adapter                 I2C adapter
i2c-0    i2c           mv64xxx_i2c adapter                 I2C adapter
root@orangepi3:~# i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@orangepi3:~# i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@orangepi3:~# i2cdetect -y 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- 27 -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@orangepi3:~# i2cdetect -y 3
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: 30 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@orangepi3:~# i2cdetect -y 4
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- UU -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@orangepi3:~#

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If I only enable i2c2 in armbian-config, then there are only three i2c buses (i2c-2, i2c-3 and i2c-4).

This means that the two default i2c buses are always at the end (in terms of numbering).

So if I don't have the i2c bus enabled in armbian-config at all, the default buses are numbered 0 and 1.

If I only have bus 0 enabled in armbian-config, the default buses have the numbers 1 and 2.

Then I went back to LE.

Instead of i2c0, I now enabled i2c2 in extlinux.conf.

Unfortunately, it behaves exactly the same as with i2c0. I.e:

A) When the FDTOVERLAYS line is at the end, LE boots, but no i2c bus is added

B) When the FDTOVERLAYS line is moved up, the boot fails

What steps can I take now (debugging?)?

**jernej** · April 21, 2021 at 5:12 PM Official Post

Quote from LuRu

Can you please specify in what sense isn't correct?

I have no clue, but it obviously doesn't work.

I wrote two overlays for I2C0 and I2C2 like so http://ix.io/2WSc (and same for I2C2). Then I included them to extlinux.conf like so FDTOVERLAYS /overlays/sun50i-h6-i2c0.dtbo /overlays/sun50i-h6-i2c2.dtbo. Now I have:

Code

LibreELEC:~ # i2cdetect -l
i2c-3   i2c             DesignWare HDMI                         I2C adapter
i2c-1   i2c             mv64xxx_i2c adapter                     I2C adapter
i2c-2   i2c             mv64xxx_i2c adapter                     I2C adapter
i2c-0   i2c             mv64xxx_i2c adapter                     I2C adapter

Note - this is on PineH64 model B, but I don't see any reason why it wouldn't work on OPi3.

Binary version of overlays: Index of /overlays/

LuRu · April 22, 2021 at 12:51 PM

Thank you for your extraordinary helpfulness and willingness to help. However, it still doesn't work, even though I used your working binary file (and it looked so promising ...).

I even tried the line

FDTOVERLAYS /overlays/sun50i-h6-ir.dtbo

or

FDTOVERLAYS /overlays/sun50i-h6-spdif.dtbo

Both of these files existed (so they were included in the installation image) in the /overlays folder. I thought it should work. But it still behaves the same - the boot fails.

So out of desperation I decompiled the file sun50i-h6-orangepi-3.dtb, edited it

Code

        i2c@5002000 {
            compatible = "allwinner,sun50i-h6-i2c", "allwinner,sun6i-a31-i2c";
            reg = <0x5002000 0x400>;
            interrupts = <0x0 0x4 0x4>;
            clocks = <0x4 0x4a>;
            resets = <0x4 0x19>;
            pinctrl-names = "default";
            pinctrl-0 = <0x26>;
            status = "okay";
            #address-cells = <0x1>;
            #size-cells = <0x0>;
            phandle = <0x63>;
        };

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and then compiled again. It works !

Code

##############################################
#                 LibreELEC                  #
#            https://libreelec.tv            #
##############################################

LibreELEC (community): nightly-20210421-5aaf229 (H6.arm)
LibreELEC:~ # i2cdetect -l
i2c-1    i2c           mv64xxx_i2c adapter                 I2C adapter
i2c-2    i2c           DesignWare HDMI                     I2C adapter
i2c-0    i2c           mv64xxx_i2c adapter                 I2C adapter
LibreELEC:~ # i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- UU -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
LibreELEC:~ # i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- 27 -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
LibreELEC:~ # i2cdetect -y 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: 30 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
LibreELEC:~ #

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But I'm not happy about it, I'd rather it worked the way over overlays.

So far, I have to work with what I have.

But it looks like it will still be many hours of work before LCDproc will work. There is little information on how to debug it.

LuRu · April 22, 2021 at 2:51 PM

Quote from LuRu

But it looks like it will still be many hours of work before LCDproc will work. There is little information on how to debug it.

So I'm surprised at how fast it went. The LCD display already shows the current Kodi informations !

Now I would like to do the correct way to enable the i2c bus via overlays. But I probably can't do it without help.

Could any OPi 3 owner help me?

**jernej** · April 22, 2021 at 6:57 PM Official Post

Fortunately, I also have OrangePi 3 I tested with fresh installation and overlays work. Try to flash latest nightly image to spare card and see if it changes anything.

For reference, my extlinux.conf:

Code

LABEL LibreELEC
  LINUX /KERNEL
  FDT /sun50i-h6-orangepi-3.dtb
  FDTOVERLAYS /overlays/sun50i-h6-i2c0.dtbo /overlays/sun50i-h6-i2c2.dtbo
  APPEND boot=UUID=2204-3027 disk=UUID=c1742531-5dac-434c-8390-f1decb06f821 quiet console=ttyS0,115200 console=tty1

NOTE: Your UUIDs will be different.

If that doesn't work, then I have no idea.

LuRu · April 23, 2021 at 3:19 PM

Great, it's finally working.

So probably the problem was that my LE was installed some time ago (although upgraded to the last night version).

Thank you again for your extraordinary support and patience.

Orange Pi 3 and i2c

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