How to Enable I2C on AML-A311D-CC

Hardware
,
1

While the AML-S905X-CC Le Potato has overlays to enable both, I2C AO and I2C B, the AML-A311D-CC currently has I2C AO enabled by default but no overlay for I2C B is available, yet.

$ ldto list
#Overlays available
cpu-b-opp-2304
cpu-l-opp-2208
npu
spifc-nor

I did find the AML-S905X-CC i2c-b.dts, but I don’t know if I can just reuse it for the AML-A311D-CC. Also the commented pins 27/28 and the used ones 26/27 seem off by one.

And pointers welcome.

I am doing this to investigate replacing the Raspberry Pi 3B+ in a pi-top[3] with the AML-A311D-CC. The pi-tobHub v2 does fit nicely and I’ll report back with my findings.

2

I created a pull request with my attemt at an i2c_b overlay for the AML-A311D-CC in Add i2c_b.dts for aml-a311d-cc by butonic · Pull Request #13 · libre-computer-project/libretech-wiring-tool · GitHub

3

Hello,
I’m also looking at enabling i2c, connecting a PWM board
Tried wiring both on pins 3,5 and 27,28, but I’m still not getting it discovered:

~ » sudo i2cdetect -y 0                                                                                       ubuntu@strong-selfo
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: 30 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

Any updates? or steps that I’m missing?

4

Nice to see another person picking this up! The advice from Tomeu Vizoso (who worked on the NPU driver but has worked on I2C in the past) was:
“I unfortunately don’t remember much about I2C (has been quite a few years), but I think you could try asking in #linux-amlogic on Libera.Chat. Or on the mailing list: http://lists.infradead.org/mailman/listinfo/linux-amlogic ”
Hope the mailing list proves fruitful!

5

I’ll post there, thanks!

Could be efficient if someone from Libre.Computer would’ve picked it up. I had great experience with Le-Potato, but this is a regression to me as

  1. I don’t have the correct background to debug it myself
  2. It was a simple straight command with the Le-Potato.
6

Couldn’t agree more! @librecomputer would you mind helping us out here?

I’m in a similar position as 1. (though I don’t even have an inkling of an idea to know what I’m doing)

7

hi, sorry for late reply…

We’ve submitted a patch[1] to enable i2c2 for Alta, tested with i2c device connected

so, can you give it a try? thanks

[1] aml-a311d-cc: enable i2c-2 controller · libre-computer-project/libretech-wiring-tool@771185a · GitHub

8

Thank you very much!
I’m afraid this is a bit beyond me for the moment but I’m sure @butonic and @gauntlet114 will be able to test it for you and I look forward to reading their feedback!

9

Hi @Luke ,
Would I assume that I need to build the wiring tool and install it on the Alta board? the use it to enable the overlay?

10

technically, yes, since it’s a dtb overlay

just download the wiring-tools repo [1], build the dtbo file (just type: make, need dtc tool installed first - can do this step either in x86 host environment or in Alta board)

then enable it use “ldto enable i2c-2”, similar as this post AML-S905X-CC (Le Potato) 480x320 ILI9486 3.5" SPI Touchscreen Display

you might want to explicitly tell ldto as following:
export VENDOR=libre-computer
export BOARD=aml-a311d-cc

[1] GitHub - libre-computer-project/libretech-wiring-tool

11

I’ve installed it before reading this message:

  1. Cloned the wiring tool repo - git clone https://github.com/libre-computer-project/libretech-wiring-tool.git
  2. Install debhelper - sudo apt install debhelper
  3. Invoke ./build.sh
  4. Invoke sudo ./install.sh
  5. Issue i2c enablement command - sudo ldto enable i2c-2
    5.1 If you want it to be permanent, issue the following command sudo ldto merge

Test that is works:

~/src/libretech-wiring-tool (master*) » sudo i2cdetect -y 1                                         ubuntu@strong-selfo
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: 40 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: 70 -- -- -- -- -- -- --

Probable note: if you did merge the device-tree, post reboot, the i2c interface numbers will swap, so one should use index 0 (zero) to interact with it. (the one the used to be 0, is now 1). there are numerous posts about that swap.

Thanks @Luke and team. (I see you responded to @butonic .

Last request, I’d like to understand the difference between I2C AO and EE, but was not able to find something that I can actually make sense of, can someone provide a useful link?

12

re AO vs EE, generally speaking, the AO means power always-on, so devices in this domain is accessible by power management auxiliary processor (a Cortex-m or riscv processor?) even during suspend or power off mode…

13

Just wondering about a timeline for how long we might expect before seeing this patch shipped in standard images?

14

Hi @Luke @librecomputer ,
When I merge and reboot the Alta board, the overlays do not persist.
Should I open a new post?

15

They are updated weekly on a continual basis via our deb servers. Images are updated every quarter or so.

16

They do persist. Once merged, it will be part of the base tree.

17

Reading the ldto script I see that the overlay name needs to be passed to the merge sub-command