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LED Strip

Tip

For a hands-on walk-through, see LED Strip in the Setup Guides and the LED Strip tab. This page is the full reference, including the CLI.

Rotorflight supports the use of addressable LED strips. Addressable LED strips allow each LED in the strip to be programmed with a unique and independent color. This is far more advanced than the normal RGB strips which require that all the LEDs in the strip show the same color.

LED Strip Profiles

The LED strip feature supports 4 LED strip profiles: RACE, BEACON, STATUS and STATUS_ALT. The selected profile can be changed from the CLI, the Lua suites, or an adjustment channel, i.e. switch on your radio. Take note that the adjustment channel from your radio overrides all other LED strip profile selection options.

STATUS Profile

The STATUS profile is used to display all the information mentioned below, i.e. warning indications, Larson scanner etc, positional lights, ACL.

Addressable LED strips can be used to show information from the flight controller system and supports:

  • Up to 32 LEDs.
  • User definable blink patterns.
  • AUX operated switching between LED profiles.
  • Indicators showing pitch/roll stick positions.
  • Heading/Orientation lights.
  • Flight mode specific color schemes.
  • Low battery warning.
  • GPS state.
  • RSSI level.
  • Battery level.

STATUS_ALT Profile

The STATUS_ALT profile works just like the STATUS_PROFILE, except for LEDs with the Fade overlay. LEDs with the Fade overlay will use their alternate color when the STATUS_ALT profile is active.

RACE Profile

The RACE profile is used to set ALL strip LEDs to the selected color for racing, i.e. to identify models by LED color. The LED color is fixed and no other information is displayed.

BEACON Profile

The BEACON profile is used to find a lost heli, it flashes all LEDs white once per second. Again in this profile no other information is displayed on the LEDs.

LED Profile Selection

OPTION 1: Use the Configurator
  1. Go to the LED Strip tab
  2. Select the profile under LED Strip Global Settings
OPTION 2: Configure an adjustment range to change the LED strip profile from your radio
  1. The LED strip profile selection is performed using an adjustment configured via the Adjustments tab.
    • Enable an adjustment by selecting Mapped.
    • Select the AUX channel to be used to change the LED strip profile under Enable channel and set the range to 900-2100us
    • Set the same AUX channel and range under Value channel
    • For the adjustment select LED Profile Selection and set the range to 1-4.
    • Save
  2. Configure the AUX channel on your radio. When this channel is changed the selected LED strip profile will change between RACE, BEACON, STATUS and STATUS_ALT. You should see the LED function change as you do this.
OPTION 3: Use the CLI to select the LED strip profile (i.e. not selecting the LED strip profile with your radio)
  1. Open the CLI.
  2. Type get ledstrip_profile followed by enter to display the currently selected LED strip profile.
  3. Type set ledstrip_profile=x where x is the profile STATUS, STATUS_ALT, RACE or BEACON and press enter.
  4. Type save followed by enter to save the selected LED strip profile.
RACE COLOR: The Race color can be configured using the CLI:
  1. Open the CLI.
  2. Type get ledstrip_race_color followed by enter to display the currently selected race color number.
  3. Type set ledstrip_race_color=x where x is the required color.
  4. Type save followed by enter to save the race color to be used.
BRIGHTNESS: The overall brightness can be configured using the CLI:
  1. Open the CLI.
  2. Type get ledstrip_brightness followed by enter to display the current brightness.
  3. Type set ledstrip_brightness=x where x is the brightness in percentage between 5 and 100.
  4. Type save followed by enter to save the brightness level to be used.

Supported hardware

Up to 32 WS2811/WS2812 LEDs are currently supported.

WS2812 LEDs require an 800khz signal and precise timings and thus requires the use of a dedicated hardware timer.

Note: Not all WS2812 ICs use the same timings, some batches use different timings.

Tested Hardware

WS2811 vs WS2812

The WS2811 is a LED driver IC which is connected to an RGB LED. It accepts data in the form of 8 bits each of Red-Green-Blue.

The WS2812 is integrated into the package of a 50:50 LED rather than as a separate device. It accepts data in the form of 8 bits each of Green-Red-Blue.

With the SK6812 also GRBW variants are supported, which have a fourth (white) channel and such provide a much cleaner white color.

It is thus possible, depending on the LED board/strip being used that either Red-Green-Blue or Green-Red-Blue encoding may be required. This may be controlled by setting the following.

set ledstrip_grb_rgb = RGB
or

set ledstrip_grb_rgb = GRB
or

set ledstrip_grb_rgb = GRBW

Then confirm the required setting by simply setting an LED to be green. If it lights up red, you have the wrong setting. Afterwards check if the second LED also lights up red - if not, you might have 4-color SK6812 LEDs and would have to select GRBW.

Combining RGB and GBR(W) LEDs

If you're using both WS2811 and WS2812/SK6812 LEDs, set ledstrip_grb_rgb to GRB or GRBW. The colors of the WS2811 LEDs will then be incorrect. To correct this, indicate which LEDs use RGB by specifying those LEDs in ledstrip_inverted_format - a 32 bit bitmask. For example, if LED 1 and 4 use RGB, specify 1 + 8 = 9:

set ledstrip_inverted_format = 9

Connections

WS2812 LED strips generally require a single data line, 5V and GND.

WS2812 LEDs on full brightness can consume quite a bit of current. It is recommended to verify the current draw and ensure your supply can cope with the load. On a multirotor that uses multiple BEC ESC's you can try use a different BEC to the one the FC uses. e.g. ESC1/BEC1 -> FC, ESC2/BEC2 -> LED strip. It's also possible to power one half of the strip from one BEC and the other half from another BEC. Just ensure that the GROUND is the same for all BEC outputs and LEDs.

LED Strip pin should be: - on a separate timer - with DMA enabled

If you have LEDs that are intermittent, flicker or show the wrong colors then drop the VIN to less than 4.7v, e.g. by using an inline diode on the VIN to the LED strip. The problem occurs because of the difference in voltage between the data signal and the power signal. The WS2811 LED's require the data signal (Din) to be between 0.3 * Vin (Max) and 0.7 * VIN (Min) to register valid logic low/high signals. The LED pin on the CPU will always be between 0v to ~3.3v, so the Vin should be 4.7v (3.3v / 0.7 = 4.71v). Some LEDs are more tolerant of this than others.

The datasheet can be found here: WS2812

Configuration

The LED strip feature can be configured via the Configurator or the CLI.

Configurator

First enable the LED_STRIP feature in the Configuration tab. The LED Strip tab should now become visible.

Now go to the LED Strip tab and configure the LEDs. First setup how the LEDs are laid out so that you can visualize it later as you configure and so the flight controller knows how many LEDs there are available.

CLI

Enable the LED_STRIP feature via the cli:

feature LED_STRIP

If you enable LED_STRIP feature and the feature is turned off again after a reboot then check your config does not conflict with other features, as above.

Configure the LEDs using the led command.

The led command takes either zero or two arguments - an zero-based LED number and a sequence which indicates pair of coordinates, direction flags and mode flags and a color.

If used with zero arguments it prints out the LED configuration which can be copied for future reference.

Each LED is configured using the following template: x,y:direction:mode:color:blinkpattern:blinkpause:alternatecolor

x and y are grid coordinates of a 0 based 16x16 grid, north west is 0,0, south east is 15,15 direction specifies the directions, since an LED can face in any direction it can have multiple directions. Directions are:

N - North E - East S - South W - West U - Up D - Down

For instance, an LED that faces South-east at a 45 degree downwards angle could be configured as SED.

Note: It is perfectly possible to configure an LED to have all directions NESWUD but probably doesn't make sense.

mode specifies the modes that should be applied an LED. A mode consists of a base function and zero or more overlays.

Each LED has one base function:

  • C - Color.
  • F - Flight mode & Orientation
  • A - Armed state.
  • R - Ring thrust state.
  • G - GPS state.
  • S - RSSSI level.
  • L - Battery Level.

And each LED can have one ore more overlays:

  • W - Wwarnings.
  • I - Indicator.
  • T - Thrust state.
  • B - Blink mode.
  • O - LarsOn Scanner (Cylon Effect).
  • V - VTX Frequency.
  • K - FlicKer.
  • D - FaDe.

color specifies the color number (0 based index). This color has a black border in the Configurator.

blinkpattern specifies a 16 bit bitmask which indicates when a LED should blink. Example: two fast blinks would be 5 (binary 101), two slow blinks 3855 (binary 111100001111). The alternatecolor is used for blinking.

blinkpause specifies whether blinking should pause after the blink pattern has been finished. A value of 0 doesn't pause blinking, a value of 3 pauses the blinking for three subsequent rounds.

alternatecolor specifies the color for: a. blinking; b. fading between color and alternatecolor if the LED profile is switched from STATUS to STATUS_ALT. The alternatecolor can be black if you want to turn a light off in in the STATUS_ALT profile. The alternate color has a red border in the Configurator.

Example:

led 0 0,15:SD:AWI:0:0:0:0
led 1 15,0:ND:AWI:0:0:0:0
led 2 0,0:ND:AWI:0:0:0:0
led 3 0,15:SD:AWI:0:0:0:0
led 4 7,7::C:1:0:0:0
led 5 8,8::C:2:0:0:0
led 6 8,9::CB:1:3855:0:2

To erase an LED, and to mark the end of the chain, use 0,0:: as the second argument, like this:

led 4 0,0:::

It is best to erase all LEDs that you do not have connected.

Modes

Warning

This mode simply uses the LEDs to flash when warnings occur.

Warning LED Pattern Notes
Arm-lock enabled flash between green and off occurs during calibration or when unarmed and the aircraft is tilted too much
Low Battery flash red and off battery monitoring must be enabled. May trigger temporarily under high-throttle due to voltage drop
Failsafe flash between light blue and yellow Failsafe must be enabled

Flash patterns appear in order, so that it's clear which warnings are enabled.

GPS state

This mode shows the GPS state and satellite count.

No fix = red LED 3D fix = green LED

The LEDs will blink as many times as the satellite count, then pause and start again.

RSSI level

This mode binds the LED color to RSSI level.

Color RSSI
Green 100%
Lime green 80%
Yellow 60%
Orange 40%
Red 20%
Deep pink 0%

When RSSI is below 50% is reached, LEDs will blink slowly, and they will blink fast when under 20%.

Battery level

This mode binds the LED color to remaining battery capacity.

Color Capacity
Green 100%
Lime green 80%
Yellow 60%
Orange 40%
Red 20%
Deep pink 0%

When Warning or Critical voltage is reached, LEDs will blink slowly or fast. Note: this mode requires a current sensor.

This overlay makes the LED blink from the current active color to the alternate color. You can set the blink rate using ledstrip_blink_period_ms.

Flicker

This overlay makes the LED flicker, a bit like a candle. Set the flicker rate using ledstrip_flicker_rate.

Fade to alt color

A LED with this overlay will fade to the alternate color in the profile STATUS_ALT. Specify Black as the alternate color to turn LEDs of (e.g. for switching off landing lights). You can set the fade rate with ledstrip_fade_rate.

Larson Scanner (Cylon Effect)

The Larson Scanner replicates the scanning "eye" effect seen on the mechanical Cylons and on Kitt from Knight Rider. This overlay dims all of the LEDs it is assigned to and brightens certain ones at certain times in accordance with the animation. The animation is active regardless of arm state.

VTX Frequency

This overlay makes the LED color dependent on the current channel of the VTX, in case it is equipped with SmartAudio or IRC Tramp. The color is selected according to the following table:

Frequency range Default color Color index
<= 5672 White 1
> 5672 <= 5711 Red
> 5711 <= 5750 Orange
> 5750 <= 5789 Yellow
> 5789 <= 5829 Green
> 5829 <= 5867 Blue
> 5867 <= 5906 Dark violet
> 5906 Deep pink

The default color can be changed by double-clicking the color and moving the Hue slider or by using the color command in the CLI.

Flight Mode & Orientation

This mode shows the flight mode and orientation.

When flight modes are active then the LEDs are updated to show different colors depending on the mode, placement on the grid and direction.

LEDs are set in a specific order: * LEDs that marked as facing up or down. * LEDs that marked as facing west or east AND are on the west or east side of the grid. * LEDs that marked as facing north or south AND are on the north or south side of the grid.

That is, south facing LEDs have priority.

The mapping between modes LED placement and colors is currently fixed and cannot be changed.

Indicator

This mode flashes LEDs that correspond to roll and pitch stick positions. i.e. they indicate the direction the craft is going to turn.

Mode Direction LED Color
Orientation North WHITE
Orientation East DARK VIOLET
Orientation South RED
Orientation West DEEP PINK
Orientation Up BLUE
Orientation Down ORANGE
Head Free North LIME GREEN
Head Free East DARK VIOLET
Head Free South ORANGE
Head Free West DEEP PINK
Head Free Up BLUE
Head Free Down ORANGE
Horizon North BLUE
Horizon East DARK VIOLET
Horizon South YELLOW
Horizon West DEEP PINK
Horizon Up BLUE
Horizon Down ORANGE
Angle North CYAN
Angle East DARK VIOLET
Angle South YELLOW
Angle West DEEP PINK
Angle Up BLUE
Angle Down ORANGE
Mag North MINT GREEN
Mag East DARK VIOLET
Mag South ORANGE
Mag West DEEP PINK
Mag Up BLUE
Mag Down ORANGE
Baro North LIGHT BLUE
Baro East DARK VIOLET
Baro South RED
Baro West DEEP PINK
Baro Up BLUE
Baro Down ORANGE

Armed state

This mode toggles LEDs between green and blue when disarmed and armed, respectively. If arming is disabled the LED will be set to the background color, which usually is black.

Note: Armed State cannot be used with Flight Mode.

Thrust state

This mode fades the current LED color to the previous/next color in the HSB color space depending on throttle stick position. When the throttle is in the middle position the color is unaffected, thus it can be mixed with orientation colors to indicate orientation and throttle at the same time. Thrust should normally be combined with Color or Mode/Orientation.

Thrust ring state

This mode is allows you to use one or multiple LED rings (e.g. NeoPixel ring) for an afterburner effect. LEDs with this mode will light up with their assigned color in a repeating sequence. Assigning the color black to an LED with the ring mode will prevent the LED from lighting up.

A better effect is achieved when LEDs configured for thrust ring have no other functions.

LED direction and X/Y positions are irrelevant for thrust ring LED state. The order of the LEDs that have the state determines how the LED behaves, and the throttle value determines the animation rate. The animation is only active while armed.

Each LED of the ring can be a different color. The color can be selected between the 16 colors available.

For example, LED 0 is set as a Ring thrust state LED in color 13 as follow.

led 0 2,2::R:13

LED strips and rings can be combined.

Solid Color

The mode allows you to set an LED to be permanently on and set to a specific color.

x,y position and directions are ignored when using this mode.

Other modes will override or combine with the color mode.

For example, to set LED 0 to always use color 10 you would issue this command.

led 0 0,0::C:10

Colors

Colors can be configured using the cli color command.

The color command takes either zero or two arguments - an zero-based color number and a sequence which indicates pair of hue, saturation and value (HSV).

See HSL and HSV

If used with zero arguments it prints out the color configuration which can be copied for future reference.

The default color configuration is as follows:

Index Color
0 black
1 white
2 red
3 orange
4 yellow
5 lime green
6 green
7 mint green
8 cyan
9 light blue
10 blue
11 dark violet
12 magenta
13 deep pink
14 black
15 black 
color 0 0,0,0
color 1 0,255,255
color 2 0,0,255
color 3 30,0,255
color 4 60,0,255
color 5 90,0,255
color 6 120,0,255
color 7 150,0,255
color 8 180,0,255
color 9 210,0,255
color 10 240,0,255
color 11 270,0,255
color 12 300,0,255
color 13 330,0,255
color 14 0,0,0
color 15 0,0,0

Mode Colors Assignement

Mode Colors can be configured using the cli mode_color command.

  • No arguments: lists all mode colors
  • arguments: mode, function, color

First 8 groups of ModeIndexes are :

mode name
0 orientation
1 headfree
2 horizon
3 angle
4 mag
5 baro
6 special
7 channel

Modes 0 to 5 functions:

function name
0 north
1 east
2 south
3 west
4 up
5 down

Mode 6 use these functions:

function name
0 disarmed
1 armed
2 animation
3 background
4 blink background
5 gps: no satellites
6 gps: no fix
7 gps: 3D fix

The ColorIndex is picked from the colors array ("palette").

Mode 7 is used along with Thrust state to make the LED color dependent on a channel different from the throttle.

Examples (using the default colors):

  • set armed color to red: mode_color 6 1 2
  • set disarmed color to yellow: mode_color 6 0 4
  • set Headfree mode 'south' to Cyan: mode_color 1 2 8
  • set color dependent on AUX 1 in Thrust state: mode_color 7 0 4

Troubleshooting

On initial power up the LEDs on the strip will be set to WHITE. This means you can attach a current meter to verify the current draw if your measurement equipment is fast enough. Most 5050 LEDs will draw 0.3 Watts a piece. This also means that you can make sure that each R,G and B LED in each LED module on the strip is also functioning. After a short delay the LEDs will show the unarmed color sequence and or low-battery warning sequence.

Also check that the feature LED_STRIP was correctly enabled and that it does not conflict with other features, as above.