Bug in P4J 2.8.0 when using I2C.regRegister (int reg, byte[] buffer, int offset, int length)

[hackerjimbo]

In summary, it ignores the offset parameter and writes from the start. What additional information would you like?

[taartspi]

hello Were you using the pigpio or the linuxfs provider ? After I fix what is broken I will inspect the other provider but wanted to start where you hit the failure. Tom

[hackerjimbo]

Good point. Here are the relevant lines from when it starts.

[main] INFO com.pi4j.runtime.impl.DefaultRuntime - Ignoring provider I2C PiGpio I2C Provider with priority 100 as lower priority than LinuxFS I2C Provider which has priority 150
[main] INFO com.pi4j.runtime.impl.DefaultRuntime - Ignoring provider I2C RaspberryPi I2C Provider with priority 0 as lower priority than LinuxFS I2C Provider which has priority 150
[main] INFO com.pi4j.library.gpiod.internal.GpioDContext - Using chip gpiochip0 pinctrl-bcm2835
[main] INFO com.pi4j.platform.impl.DefaultRuntimePlatforms - adding platform to managed platform map [id=raspberrypi; name=RaspberryPi Platform; priority=5; class=com.pi4j.plugin.raspberrypi.platform.RaspberryPiPlatform]

So it looks like it's using the LinuxFS provider, I just can't spot where it says that.

One thing I didn't spot was the interface definition for the signature in the bug subject. I found one with byte[] register and tried that with a single byte array but still hit the same fault.

Many thanks for your help with this!

Jim.

[taartspi]

Yep. My bug in the linuxfs i2c i did and is specific to that provider. Looks simple to fix and test. I will get you a fix. Thanks for the details

[taartspi]

Also. As i jump around between various providers I drop this code into my test cases.

System.out.println("-------------------------------------------------");
System.out.println("PI4J PROVIDERS");
System.out.println("-------------------------------------------------");
pi4j.providers().describe().print(System.out);
System.out.println("-------------------------------------------------");

[taartspi]

Pull Request #468 has my fix.

[FDelporte]

@hackerjimbo are you on Java runtime 21 or higher? Because if we implement this fix into development, it will appear in the next V3 version which requires Java 21.

[hackerjimbo]

I'm using Java 11 and v2.0.8 because I'm running on a Pi 1. I could apply the patch to that version though. I also have the hack that allows it to run on the ARM v6 architecture.

[FDelporte]

Oh wow, great to hear "modern" Pi4J also still works on Pi 1 :-)

[hackerjimbo]

I'm using V2 Pi4J because v3 needs Java 21 and that's not available on the ARM v6 architecture. I have several Pi 1s and 0s and they can't run anything higher than Java 11. having said which, the performance is quite reasonable.