LED Strip

Rotorflight supports the use of addressable LEDs. Addressable LEDs allow each LED to be programmed with a unique and independent color. Addressable LEDs are available as individual LEDs (usually 5mm or 8mm) or LED strips.

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 Configurator, CLI, OSD LED strip menu or from 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, positional lights, ACL, etc.

Addressable LEDs 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 LEDs to the selected color for racing, i.e. to identify helis based on 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.

OPTION 4: By using the OSD

1. Open the OSD menu by yawing left and pitching forward on your radio.
2. Using the pitch stick, move down to the LED Strip menu and roll right to enter the menu.
3. The profile and race color can be configured using the left stick to go back and the right stick to navigate up/down and to change the selected value.
4. Use the left stick to go to the top level menu and select save & reboot to complete.

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

• Adafruit NeoPixel Jewel 7 (preliminary testing)
  • Measured current consumption in all white mode ~ 350 mA.
  • Fits well under motors on mini 250 quads.
• Adafruit NeoPixel Stick (works well)
  • Measured current consumption in all white mode ~ 350 mA.
• Aliexpress SK6812 RBGWW strip (works well)
  • Alternative Adafruit NeoPixel Stick RGBW

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. It's also possible to power one half of the LEDs 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.

There is a step by step guide on how to use the Configurator to configure the Led Strip feature which was published in 2018 by Oscar Liang.

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

Note: though this section does apply to Rotorflight, it mainly stems form Betaflight and is thus very quad oriented.

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. If you don't have the actual device you can set up a virtual current sensor.

Blink

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 off (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	2
> 5711 < = 5750	Orange	3
> 5750 < = 5789	Yellow	4
> 5789 < = 5829	Green	6
> 5829 < = 5867	Blue	10
> 5867 < = 5906	Dark violet	11
> 5906	Deep pink	13

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

Positioning

Cut the strip into sections as per diagrams below. When the strips are cut ensure you reconnect each output to each input with cable where the break is made. e.g. connect 5V out to 5V in, GND to GND and Data Out to Data In.

Orientation is when viewed with the front of the aircraft facing away from you and viewed from above.

Example 12 LED config

The default configuration is as follows

led 0 15,15:ES:IA:0
led 1 15,8:E:WF:0
led 2 15,7:E:WF:0
led 3 15,0:NE:IA:0
led 4 8,0:N:F:0
led 5 7,0:N:F:0
led 6 0,0:NW:IA:0
led 7 0,7:W:WF:0
led 8 0,8:W:WF:0
led 9 0,15:SW:IA:0
led 10 7,15:S:WF:0
led 11 8,15:S:WF:0
led 12 7,7:U:WF:0
led 13 8,7:U:WF:0
led 14 7,8:D:WF:0
led 15 8,8:D:WF:0
led 16 8,9::R:3
led 17 9,10::R:3
led 18 10,11::R:3
led 19 10,12::R:3
led 20 9,13::R:3
led 21 8,14::R:3
led 22 7,14::R:3
led 23 6,13::R:3
led 24 5,12::R:3
led 25 5,11::R:3
led 26 6,10::R:3
led 27 7,9::R:3
led 28 0,0:::0
led 29 0,0:::0
led 30 0,0:::0
led 31 0,0:::0

Which translates into the following positions:

     6             3
      \           /
       \   5-4   /
        \ FRONT /
    7,8 | 12-15 | 1,2
        /  BACK \
       /  10,11  \
      /           \
     9             0
       RING 16-27

LEDs 0,3,6 and 9 should be placed underneath the quad, facing downwards. LEDs 1-2, 4-5, 7-8 and 10-11 should be positioned so the face east/north/west/south, respectively. LEDs 12-13 should be placed facing down, in the middle LEDs 14-15 should be placed facing up, in the middle LEDs 16-27 should be placed in a ring and positioned at the rear facing south.

This is the default so that if you don't want to place LEDs top and bottom in the middle just connect the first 12 LEDs.

Example 16 LED config

led 0 15,15:SD:IA:0
led 1 8,8:E:FW:0
led 2 8,7:E:FW:0
led 3 15,0:ND:IA:0
led 4 7,7:N:FW:0
led 5 8,7:N:FW:0
led 6 0,0:ND:IA:0
led 7 7,7:W:FW:0
led 8 7,8:W:FW:0
led 9 0,15:SD:IA:0
led 10 7,8:S:FW:0
led 11 8,8:S:FW:0
led 12 7,7:D:FW:0
led 13 8,7:D:FW:0
led 14 7,7:U:FW:0
led 15 8,7:U:FW:0

Which translates into the following positions:

     6             3
      \           /
       \   5-4   /
      7 \ FRONT / 2
        | 12-15 |
      8 /  BACK \ 1
       /  10-11  \
      /           \
     9             0

LEDs 0,3,6 and 9 should be placed underneath the quad, facing downwards. LEDs 1-2, 4-5, 7-8 and 10-11 should be positioned so the face east/north/west/south, respectively. LEDs 12-13 should be placed facing down, in the middle LEDs 14-15 should be placed facing up, in the middle

Example 28 LED config

#right rear cluster
led 0 9,9:S:FWT:0
led 1 10,10:S:FWT:0
led 2 11,11:S:IA:0
led 3 11,11:E:IA:0
led 4 10,10:E:AT:0
led 5 9,9:E:AT:0
# right front cluster
led 6 10,5:S:F:0
led 7 11,4:S:F:0
led 8 12,3:S:IA:0
led 9 12,2:N:IA:0
led 10 11,1:N:F:0
led 11 10,0:N:F:0
# center front cluster
led 12 7,0:N:FW:0
led 13 6,0:N:FW:0
led 14 5,0:N:FW:0
led 15 4,0:N:FW:0
# left front cluster
led 16 2,0:N:F:0
led 17 1,1:N:F:0
led 18 0,2:N:IA:0
led 19 0,3:W:IA:0
led 20 1,4:S:F:0
led 21 2,5:S:F:0
# left rear cluster
led 22 2,9:W:AT:0
led 23 1,10:W:AT:0
led 24 0,11:W:IA:0
led 25 0,11:S:IA:0
led 26 1,10:S:FWT:0
led 27 2,9:S:FWT:0

       16-18  9-11
19-21 \           / 6-8
       \  12-15  /
        \ FRONT /
        /  BACK \
       /         \
22-24 /           \ 3-5
       25-27   0-2

All LEDs should face outwards from the chassis in this configuration.