LED Support for Dev A and Dev C

[chengguizi]

We would like Dev A board to have Nuttx Status LED enabled (CONFIG_ARCH_LEDS)

Dev A only has a RGB led, so we should use it for status only, not for user.

For Nuttx internal, the control API is

• board_autoled_initialize()
• board_autoled_on() and board_autoled_off()

which are enabled by CONFIG_ARCH_LEDS, depending on CONFIG_ARCH_HAVE_LEDS

That is to say, if we want to disable autoled function, controlled by Nuttx, we should turn off CONFIG_ARCH_LEDS. This should be the setting for Dev C, as the number of leds are limited.

Proposed work:

• Dev A will have the right-hand side red and green led assigned as Nuttx Status LEDs
• Dev C will NOT be assigned with any Nuttx Status LEDs (ARCH_HAVE_LEDS deselected)
• Both boards will support user leds (CONFIG_ARCH_HAVE_LEDS selected)

[chengguizi]

PX4 supports status indication through a RGB LED hardware. I believe it is controlled using I2C bus.

Therefore, we should use external I2C RGB LED hardware to support PX4 indication, and leave the on-board LEDs solely for Nuttx or user.

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