[DRAFT] Support for RGBW leds

[mrchantey]

I've had some success modifying the smart_leds_adapter for RGBW. The implementation is identical to the existing adapter, just with three changes:

1. Use the RGBA8 color type instead of RGB8
2. A buffer size of 32 instead of 24,
3. Apply the white component in the convert_rgb_to_pulse function.

I've tried to balance simplicity with code sharing, the only duplication is the write function, I couldn't think of a simple way to expose that.

If this is out of scope for the crate it would be greatly appreciated if the smart_led_adapter.rs change (or something similiar) made it through so that we can hook into the setup and pulse generation from other crates and benefit from any updates made here.

On a 'lighter' note, the rgbw variant is quite popular and the white channel provides some really beautiful colors when mixed with rgb.

[bjoernQ]

Thanks for your contribution! I guess we can merge this (any objections @jessebraham ?)

Long term the SmartLEDs adapters should probably get moved into their own crates however

[jessebraham]

Yeah I'd still like to get rid of the adapter eventually, but I don't think that's a reason to not merge this. Not like we've really even discussed that further since it was added. So no objections here.

[mrchantey]

Long term the SmartLEDs adapters should probably get moved into their own crates

Yes that makes sense, this direction might be a bit of a pandoras box. The alternative to the merge is I just work on a new crate. Over the next few weeks I'll likely be doing more work with the leds and a few other sensors like the MPU6050, so the crate might end up being a bit more generic than leds, something like esp_extra.

[bjoernQ]

Sounds great!

Regarding the MPU6050 there were some issues when first time talking to it - it just doesn't ACK the first transfers for some reason.

A simple workaround is to try reading the WHOAMI register until it works, like this:

let mut buffer = [0x00];
let res = i2c.write_read(0x68, &[0x75], &mut buffer);

As soon as that works, I had no issues with it

[bjoernQ]

Sounds great!

Regarding the MPU6050 there were some issues when first time talking to it - it just doesn't ACK the first transfers for some reason.

A simple workaround is to try reading the WHOAMI register until it works, like this:

let mut buffer = [0x00];
let res = i2c.write_read(0x68, &[0x75], &mut buffer);

As soon as that works, I had no issues with it

As of #263 the workaround shouldn't be needed anymore

[mrchantey]

The alternative to the merge is I just work on a new crate.

FYI I've fallen down an unrelated rabbit hole and am not currently working on this.

[bjoernQ]

Thanks for letting us know!