Change NeoPixel Length for NTF LEDs

[eovnu87435ds]

This change allows more than a single NeoPixel in a chain be used for an NTF LED. In particular, I had some PCBs with 8 pixels on them, and I was able to dynamically change the number of status LEDs from 1 to 8 using parameter NTF_NEO_LEN.

Tested using Plane master on an omnibusf4pro.

Not sure if this has to do with my shoddy code but whenever I write a new value to NTF_NEO_LEN, mission planner disconnects from the aircraft.

I don't really know much C++ and this is my first ArduPilot edit, so looking for any criticism you might have.

[IamPete1]

Do we need a param? Any disadvantage to just setting it to some larger number say 10? I guess we would output to LEDs that are not there, but I don't think that can be too much overhead.

[eovnu87435ds]

@IamPete1 not sure. It would be cool to have the option of using arrays like this (I've been thinking about a similar concept for large multirotors). Going with an extremely large default string would probably do nothing but eat up memory for the majority of users, but I guess if there's a user-selected string length, then there probably has to be a safeguard to prevent out of memory issues?

[tridge]

I think this is a good idea, thanks, just some minor issues I've noted

[rmackay9]

This PR came up as solution to a support issue during Copter-4.0 testing so I vote for this going in. https://discuss.ardupilot.org/t/ws2812b-neopixel-integration/48580/30

[rmackay9]

By the way, the commits should be squashed together to a single commit (no need for multiple commits to the same lines of code) and the commit description should start with "AP_Notify: ". Thanks!

[eovnu87435ds]

Just made the fixes, I'll have to change the commit comment and I should be good

[eovnu87435ds]

@rmackay9 let me know if I should change how I have the commit commented.

[IamPete1]

looks good to me, just need to squash the three commits together with the name of the last

[eovnu87435ds]

looks good to me, just need to squash the three commits together with the name of the last

whoops, all taken care of now

Fixed

[rmackay9]

There was a request that we included this in Copter-4.0.4. I'm a bit reluctant to do that considering it's not a really critical fix .. still, I wanted to record the request somewhere.

[IamPete1]

@rmackay9 I think this got into 4.0 with the ProfiLED stuff.