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RS: Set individual LEDs, EXP Bus Protocol Reference

Understanding EXP board addressing

This command is used with FAST Expansion and FAST breakout boards via a FAST Serial Protocol (FSP) connection to the EXP Bus. Please read the EXP Overview to understand the operation of these commands and addresses.

This command is used to set individual RGB LEDs to a specific color. You can chain together multiple LEDs and colors in a single command.

Note that there is also a binary version of this command, RD:, which might be more appropriate for your use case.

Command Syntax

RS:<index><rgb>[,<index><rgb>...]<cr>

<index>

This is the LED number for the LED you want to update. Individual LEDs are accessed via hex 00 - 7F (0-127) since that's the max LEDs that can be attached to a single breakout board.

New in firmware 0.20:

You can also use mapped LED blocks which you configured via the LM: command. In this case, all the LEDs in that set will be updated to the same color as if they were a single LED.

If LED maps have previously been created on the expansion board targetted, then LED indexes 80-FF correspond to the mapped LED sets.

<rgb>

RGB color value as a single ASCII hex number, with each channel in the range of 0-255 (0x00 - 0xFF hex). This is combined with the index into a 4 byte / 8 character hex argument.

Examples

You can update more than one LED at a time with this command by putting commas between each LED.

For example, to update three LEDs:

  • LED 01 - red (ff00ff)
  • LED 24 - yellow (ffff00)
  • LED 7A - blue (0000ff)

The command would look like this:

RS:01FF00FF,24FFFF00,7A0000FF<CR>

Breaking it down:

  • RS: command name
  • 01FF00FF set LED 01 to FF00FF
  • 24FFFF00 set LED 24 to FFFFOO
  • 7A0000FF set LED 7A to OOOOFF
  • <CR> at the end

If you have a global fade rate set (via a previously-sent RF: command for the board the LEDs are attached to), then the LEDs will fade to that rate over the given time.

Return Response

None

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