Hello,
i am using Venus 2.9 on Raspberry-Pi. I am using it for my PV-equipment.
To get a system overview (e.g. Current solar power, power consumption) i wanted to add a
4x20 character display controlled over I2C (8574T) bus. The displayed data should be contolled by NodeRed.
It works fine with Raspberry OS but not with Venus OS.
Any hints why the I2C-Bus can not be accessed via Node Red?
With best regards
Peter
I have this in /u-boot/config.txt
dtparam=i2c_arm=on
dtparam=i2c1=on
The Pi's I2C1 is connected to the i2c of the 8574 via an i2c optical isolator. In my case, I don't use it as an expander, but to directly control relays from node-red.
Thank you,
so it is good to know that it works principally.
I have tried to add the configuration but unfortunately i get:
Error: ENOENT: no such file or directory, open '/dev/i2c-1
Did you have same experiences? Or was ist a straight on procedure?
First, you can start by testing whether the device is connected to the pi.
i2cdetect -y 1
root@raspberrypi4:~# 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: -- UU -- -- -- UU -- -- -- -- -- 5b -- -- -- --
60: -- -- -- -- -- -- UU -- UU -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
This is from my pi4 with venus.os 2.92
Runs several I2C devices such as relay controller, voltmeter, bidirectional ammeter, real time clock tank sensor on only 1 i2c / gpio connection.
Also uses some python/C# libraries for various purposes, but all management and reading of data takes place in node-red.
My system is probably a bit of an 'eye-candy' for most people, but I like analogue because of the age :=)
Interessting. This is what i got:
i2cdetect: can't open '/dev/i2c/1': No such file or directory
By the way, your instruments look really nice. And i agree, sometimes analog instruments are much easier and faster to read. I guess this is no matter of age :)
You can try adding this line to /u-boot/config.txt
dtoverlay=i2c1
but you need to download i2c1.dtbo to /u-boot/overlays/
https://github.com/raspberrypi/firmware/blob/master/boot/overlays/i2c1.dtbo
Otherwise, I don't know why it doesn't work for you, maybe some difference between the venus-os versions?
A short update. I found this:
So it seems to be necessary to modify rc.local -file
and add:
modprobe i2c-dev
within this file i also found an entry:
/data/dbus-iobroker-smartmeter/install.sh
Which i disabled. It might be, that i crashed the installation with prior experiments.
Now, at least the i2cdetect -l
leading to a lot of i2c hardware. I did not expect to have so many i2c hardware on my Pi3+
i2c-1 i2c bcm2835 (i2c@7e804000) I2C adapter
i2c-11 i2c bcm2835 (i2c@7e205000) I2C adapter
i2c-0 i2c i2c-11-mux (chan_id 0) I2C adapter
i2c-10 i2c i2c-11-mux (chan_id 1) I2C adapter
And now the 8574 was found
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: -- -- -- -- -- -- -- --
But still node red responds with an error:
"i2c port not open or adress used, check i2c settings"
I am working on it.
But for now, thanks for your help. I will complete this thread if i found a solution.
Great that you figure it out.
I remember it now, had to create an udev rule for node-red to get access to i2c. possibly there are other ways to do this
SUBSYSTEM=="i2c-dev", MODE="0666"
Hi,
now after a few days i started working on it again. And: It works!!!!
It took me only a few minutes.
I only added a file: 99-i2c.rules
in the /etc/udev/rules.d
directory. Then i added:
SUBSYSTEM=="i2c-dev", MODE="0666"as you recommended.
After
chmod 777 99-i2c.rules
(not shure if its necessary), and a reboot the display works!!!
All the steps are summarized here:
https://github.com/fivdi/i2c-bus/blob/master/doc/raspberry-pi-i2c.md
So thank you for your help. How can i spend you a coffee?
With best greetings and happy easter
Peter
