External Led not working on Pixhawk

I use Neopixel leds connected through arduino on I2c port for status on pixhawk
everything worked ok on 3.4.6. stopped working after upgrading to 3.5.
downgraded and working again. code for arduino by Stefan Gofferje.
Has anyone experienced this?

I monitored the data on the I2c External Led. on 3.4.6 I get 0x81 ;0x82;0x83. Then it works. on 3.5 I get 0x0;0xf;0x1. not sure why this happens. I am using 3.4.6 for now until I can figure this out.

+1 for this issue. I’ve created a bug report here: https://github.com/ArduPilot/ardupilot/issues/6897

I see your bug report has been removed. This is the reason I have never upgraded to 3.5. I have 8 leds per arm on my octoquad. I love flying at night(create ufo scare).

So I figured out the issue… AC3.5 uses new drivers in AP_Notify. Specifically for my issue was the Toshiba LED driver that now uses the more efficient 4-byte addressing protocol instead of the old 6-byte protocol.

@freezer I’m not sure of your exact hardware setup but this may well be your issue too?

Did you get your setup to work? my external leds works by emulating the Toshiba external led. when I connect it to the I2c port , the pixhawk internal led goes off, but still no output on my leds. I also use Attiny programmed with arduino. I will send you more info once I get home after work.

Yes my LED code is now working. My Toshiba emulation is parasitic, that is, it only listens in on the I2C communication. So it requires an actual Toshiba driver to be connected (either on the Pixhawk or on the GPS) for it to work correctly.
When I have a spare moment I’ll upload my code to the examples section of ArduPilot and you can see what I’ve done.

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I like that idea: a bit of a compromise, but enables any number of additional leds.

Ok so what I have done is the following. I took the red , green and blue output from the onboard led through an uln2003 to drive more leds. a bit of an hack ,but works. no programming needed.