LSS - Communication Protocol

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(% class="wikigeneratedid" id="HTableofContents" %)

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**Table of Contents**

= Serial Protocol Concept =

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The custom Lynxmotion Smart Servo (LSS) serial protocol was created in order to be as simple and straightforward as possible from a user perspective ("human readable format"), while at the same time compact and robust yet highly versatile. The protocol was based on Lynxmotion's SSC-32 RC servo controller and almost everything one might expect to be able to configure for a smart servo motor is available.

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In order to have servos react differently when commands are sent to all servos in a serial bus, the first step a user should take is to assign a different ID number to each servo (explained below). Once this has been done, only the servo(s) which have been assigned to the ID sent as part of the command will follow that command. There is currently no CRC / checksum implemented as part of the protocol.

== Session ==

A "session" is defined as the time between when the servo is powered ON to when it is powered OFF or reset.

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== Action Commands ==

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Action commands tell the servo, within that session, to do something (i.e. "take an action"). The types of action commands which can be sent are described below, and they cannot be combined with other commands such as queries or configurations. Only one action command can be sent at a time. Action commands are session-specific, therefore once a servo is power cycled, it will not have any "memory" of previous actions or virtual positions (described below on this page). Action commands are sent serially to the servo's Rx pin and must be sent in the following format:

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1. Start with a number sign # (U+0023)

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1. Servo ID number as an integer

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1. Action command (one to three letters, no spaces, capital or lower case)

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1. Action value in the correct units with no decimal

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1. End with a control / carriage return '<cr>'

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Ex: #5PD1443<cr>

This sends a serial command to all servo's Rx pins which are connected to the bus and only servo(s) with ID #5 will move to a position in tenths of degrees ("PD") of 144.3 degrees. Any servo on the bus which does not have ID 5 will take no action when receiving this command.

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== Action Modifiers ==

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Only two commands can be used as action modifiers: Timed Move (T) and Speed (S) described below. Action modifiers can only be used with certain action commands. The format to include a modifier is:

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1. Start with a number sign # (U+0023)

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1. Servo ID number as an integer

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1. Action command (one to three letters, no spaces, capital or lower case)

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1. Action value in the correct units with no decimal

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1. Modifier command (one letter)

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1. Modifier value in the correct units with no decimal

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1. End with a control / carriage return '<cr>'

Ex: #5P1456T1263<cr>

This results in the servo with ID #5 rotating from the current angular position to a pulse position ("P") of 1456 in a time ("T") of 1263 milliseconds.

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== Configuration Commands ==

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Configuration commands and corresponding values affect a servo's defaults which are written to and read from the servo's EEPROM. These configurations are retained in memory after the servo is reset or power is cut / lost. Some configuration commands affect the session, while others do not (see each command for details). Not all action commands have a corresponding configuration and vice versa. More information about which configuration commands are retained when in RC mode can be found on the [[LSS - RC PWM page>>doc:Lynxmotion Smart Servo (LSS).LSS - RC PWM.WebHome]]. Configuration commands are not cumulative, in that if two configurations are sent, one after the next, only the last configuration is used and stored. The format to send a configuration command is identical to that of an action command:

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1. Start with a number sign # (U+0023)

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1. Servo ID number as an integer

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1. Configuration command (two to three letters, no spaces, capital or lower case)

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1. Configuration value in the correct units with no decimal

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1. End with a control / carriage return '<cr>'

Ex: #5CO-50<cr>

This configures an absolute origin offset ("CO") with respect to factory origin to servo with ID #5 and changes the offset for that session to -5.0 degrees (50 tenths of degrees). Once the servo is powered off and then powered on, zeroing the servo will cause it to move to -5.0 degrees with respect to the factory origin and report its position as 0 degrees. Configuration commands can be undone / reset either by sending the servo's default value for that configuration, or by doing a factory reset (clears all configurations) described below.

== Query Commands ==

Query commands request information from the servo. They are received via the Rx pin of the servo, and the servo's reply is sent via the servo's Tx pin. Using separate lines for Tx and Rx is called "full duplex". Query commands are also similar to action and configuration commands and must use the following format:

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1. Start with a number sign # (U+0023)

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1. Servo ID number as an integer

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1. Query command (one to three letters, no spaces, capital or lower case)

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1. End with a control / carriage return '<cr>'

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Ex: #5QD<cr>Query position in degrees for servo #5

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The query will return a serial string (almost instantaneously) via the servo's Tx pin with the following format:

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1. Start with an asterisk * (U+002A)

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1. Servo ID number as an integer

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1. Query command (one to three letters, no spaces, capital letters)

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1. The reported value in the units described, no decimals.

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1. End with a control / carriage return '<cr>'

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There is currently no option to control how fast a servo replies after it has received a query command, therefore when sending a query command to the bus, the controller should be prepared to immediately "listen" for and parse the reply. Sending multiple queries on a bus in fast succession may result in replies overlapping and giving incorrect or corrupt data. As such, the controller should receive a reply before sending a new command. A reply to the query sent above might be:

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Ex: *5QD1443<cr>

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This indicates that servo #5 is currently at 144.3 degrees (1443 tenths of degrees).

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**Session vs Configuration Query**

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By default, the query command returns the sessions' value. Should no action commands have been sent to change the session value, it will return the value saved in EEPROM which will either be the servo's default, or modified with a configuration command. In order to query the value stored in EEPROM (configuration), add a '1' to the query command:

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Ex: #5CSR20<cr> immediately sets the maximum speed for servo #5 to 20rpm (explained below) and changes the value in memory.

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After RESET, a command of #5SR4<cr> sets the session's speed to 4rpm, but does not change the configuration value in memory. Therefore:

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#5QSR<cr> would return *5QSR4<cr> which represents the value for that session, whereas

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#5QSR1<cr> would return *5QSR20<cr> which represents the value in EEPROM

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== Virtual Angular Position ==

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The ability to store a "virtual angular position" is a feature which allows for rotation beyond 360 degrees, permitting multiple rotations of the output horn, moving the center position and more. In virtual position mode, the "absolute position" would be the angle of the output shaft with respect to a 360.0 degree circle, and can be obtained by taking the modulus (with respect to 360 degrees) of the value. For example if the virtual position is reported as 15335 (or 1533.5 degrees), taking the modulus would give 93.5 degrees (3600 * 4 + 935 = 15335) as the absolute position (assuming no origin offset).

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[[image:LSS-servo-positions.jpg]]

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In this example, the gyre direction (explained below, a.k.a. "rotation direction") is positive (clockwise), and origin offset has not been modified. Each square represents 30 degrees. The following command is sent:

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#1D-300<cr> This causes the servo to move to -30.0 degrees (green arrow)

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#1D2100<cr> This second position command is sent to the servo, which moves it to 210.0 degrees (orange arrow)

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#1D-4200<cr> This next command rotates the servo counterclockwise to a position of -420 degrees (red arrow), which means one full rotation of 360 degrees plus 60.0 degrees (420.0 - 360.0), with a virtual position of -420.0 degrees.

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Although the final physical position would be the same as if the servo were commanded to move to -60.0 degrees, the servo is in fact at -420.0 degrees.

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#1D4800<cr> This new command is sent which would then cause the servo to rotate from -420.0 degrees to 480.0 degrees (blue arrow), which would be a total of 900 degrees of clockwise rotation, or 2.5 complete rotations.

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#1D3300<cr> would cause the servo to rotate from 480.0 degrees to 330.0 degrees (yellow arrow).

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If / once the servo loses power or is power cycled, it also loses the virtual position associated with that session. For example, if the virtual position was 480.0 degrees before power is cycled, upon power up the servo's position will be read as +120.0 degrees from zero (assuming center position has not been modified).

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= Command List =

| 1|[[**L**imp>>||anchor="H1.Limp28L29"]]| L| | | | ✓|none|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)

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| 2|[[**H**alt & **H**old>>||anchor="H2.Halt26Hold28H29"]]| H| | | | ✓|none|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)

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| 3|[[**T**imed move>>||anchor="H3.Timedmove28T29"]]| T| | | | ✓|milliseconds|(% style="width:510px" %) Modifier only for {P, D, MD}|(% style="text-align:center; width:113px" %)

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| 4|[[**S**peed>>||anchor="H4.Speed28S29"]]| S| | | | ✓|microseconds per second|(% style="width:510px" %) Modifier only {P}|(% style="text-align:center; width:113px" %)

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| 5|[[**M**ove in **D**egrees (relative)>>||anchor="H5.28Relative29MoveinDegrees28MD29"]]| MD| | | | ✓|tenths of degrees (ex 325 = 32.5 degrees)|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)

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| 6|[[**O**rigin Offset>>||anchor="H6.OriginOffsetAction28O29"]]| O| QO| CO| ✓| ✓|tenths of degrees (ex 91 = 9.1 degrees)|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)(((

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| 7|[[**A**ngular **R**ange>>||anchor="H7.AngularRange28AR29"]]| AR| QAR| CAR| ✓| ✓|tenths of degrees |(% style="width:510px" %) |(% style="text-align:center; width:113px" %)(((

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| 8|[[Position in **P**ulse>>||anchor="H8.PositioninPulse28P29"]]| P| QP| | | ✓|microseconds|(% style="width:510px" %)(((

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Inherited from SSC-32 serial protocol

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)))|(% style="text-align:center; width:113px" %)

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| 9|[[Position in **D**egrees>>||anchor="H9.PositioninDegrees28D29"]]| D| QD| | | ✓|tenths of degrees |(% style="width:510px" %) |(% style="text-align:center; width:113px" %)

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| 10|[[**W**heel mode in **D**egrees>>||anchor="H10.WheelModeinDegrees28WD29"]]| WD| QWD| | | ✓|tenths of degrees per second (ex 248 = 24.8 degrees per second)|(% style="width:510px" %)A.K.A. "Speed mode" or "Continuous rotation"|(% style="text-align:center; width:113px" %)

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| 11|[[**W**heel mode in **R**PM>>||anchor="H11.WheelModeinRPM28WR29"]]| WR| QWR| | | ✓|revolutions per minute (rpm)|(% style="width:510px" %)A.K.A. "Speed mode" or "Continuous rotation"|(% style="text-align:center; width:113px" %)

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| 12|[[Max **S**peed in **D**egrees>>||anchor="H12.SpeedinDegrees28SD29"]]| SD| QSD|CSD| ✓| ✓|tenths of degrees per second |(% style="width:510px" %)(((

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QSD: Add modifier "2" for instantaneous speed.

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SD overwrites SR / CSD overwrites CSR and vice-versa.

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)))|(% style="text-align:center; width:113px" %)Max per servo

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| 13|[[Max **S**peed in **R**PM>>||anchor="H13.SpeedinRPM28SR29"]]| SR| QSR|CSR| ✓| ✓|revolutions per minute (rpm)|(% style="width:510px" %)(((

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QSR: Add modifier "2" for instantaneous speed

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SR overwrites SD / CSR overwrites CSD and vice-versa.

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)))|(% style="text-align:center; width:113px" %)Max per servo

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| 16|[[**LED** Color>>||anchor="H16.RGBLED28LED29"]]| LED| QLED| CLED| ✓| ✓|none (integer from 0 to 8)|(% style="width:510px" %)0=Off (black); 1=Red 2=Green; 3=Blue; 4=Yellow; 5=Cyan; 6=Magenta; 7=White;|(% style="text-align:center; width:113px" %)7

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| 17|[[**ID** #>>||anchor="H17.IdentificationNumber"]]| | QID| CID| | ✓|none (integer from 0 to 250)|(% style="width:510px" %)Note: ID 254 is a "broadcast" which all servos respond to|(% style="text-align:center; width:113px" %)0

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| 18|[[**B**aud rate>>||anchor="H18.BaudRate"]]| B| QB| CB| | ✓|none (integer)|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)9600

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| 19|[[**G**yre direction (**G**)>>||anchor="H19.GyreRotationDirection"]]| G| QG| CG| ✓| ✓|none |(% style="width:510px" %)Gyre / rotation direction where 1= CW (clockwise) -1 = CCW (counter-clockwise)|(% style="text-align:center; width:113px" %)1

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| 20|[[**F**irst Position (**P**ulse)>>||anchor="H20.First2InitialPosition28pulse29"]]| | QFP|CFP | ✓| ✓|none |(% style="width:510px" %)CFP overwrites CFD and vice-versa|(% style="text-align:center; width:113px" %)(((

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Limp

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| 21|[[**F**irst Position (**D**egrees)>>||anchor="H21.First2InitialPosition28Degrees29"]]| | QFD|CFD| ✓| ✓|none |(% style="width:510px" %)CFD overwrites CFP and vice-versa|(% style="text-align:center; width:113px" %)Limp

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| 22|[[**T**arget (**D**egree) **P**osition>>||anchor="H22.QueryTargetPositioninDegrees28QDT29"]]| | QDT| | | ✓|tenths of degrees (ex 325 = 32.5 degrees; 91 = 9.1 degrees)|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)

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| 23|[[**M**odel **S**tring>>||anchor="H23.QueryModelString28QMS29"]]| | QMS| | | |none (string)|(% style="width:510px" %) Returns the type of servo (ST, HS, HT)|(% style="text-align:center; width:113px" %)

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| 24|[[Serial **N**umber>>||anchor="H24.QuerySerialNumber28QN29"]]| | QN| | | |none (integer)|(% style="width:510px" %) Returns the unique serial number for that servo|(% style="text-align:center; width:113px" %)

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| 25|[[**F**irmware version>>||anchor="H25.QueryFirmware28QF29"]]| | QF| | | |none (integer)|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)

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| 26|[[**Q**uery (general status)>>||anchor="H26.QueryStatus28Q29"]]| | Q| | | ✓|none (integer from 1 to 8)|(% style="width:510px" %) See command description for details|(% style="text-align:center; width:113px" %)

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| 27|[[**V**oltage>>||anchor="H27.QueryVoltage28QV29"]]| | QV| | | ✓|millivolts (ex 5936 = 5936mV = 5.936V)|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)

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| 28|[[**T**emperature>>||anchor="H28.QueryTemperature28QT29"]]| | QT| | | ✓|tenths of degrees Celsius|(% style="width:510px" %)Max temp before error: 85°C (servo goes limp)|(% style="text-align:center; width:113px" %)

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| 29|[[**C**urrent>>||anchor="H29.QueryCurrent28QC29"]]| | QC| | | ✓|milliamps (ex 200 = 0.2A)|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)

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| 30a|[[**RC** Mode>>||anchor="H30.RCMode28CRC29"]] - Position| | |CRC1| | ✓|none|(% style="width:510px" %)(((

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Puts the servo into RC mode. To revert to smart mode, use the button menu.

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)))|(% style="text-align:center; width:113px" %)Serial

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| 30b|[[**RC** Mode>>||anchor="H30.RCMode28CRC29"]] - Wheel| | |CRC2| | ✓| |(% style="width:510px" %) |(% style="text-align:center; width:113px" %)

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| 31|[[**RESET**>>||anchor="H31.RESET"]]| | | | | ✓|none|(% style="width:510px" %)Soft reset. See command for details.|(% style="text-align:center; width:113px" %)

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| 32|[[**DEFAULT**>>||anchor="H32.DEFAULTA026CONFIRM"]]| | | | |✓|none|(% style="width:510px" %)Revert to firmware default values. See command for details|(% style="text-align:center; width:113px" %)

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| 33|[[**UPDATE**>>||anchor="H33.UPDATEA026CONFIRM"]]| | | | |✓|none|(% style="width:510px" %)Update firmware. See command for details.|(% style="text-align:center; width:113px" %)

== Advanced ==

| 1|[[**A**ngular **S**tiffness>>||anchor="H14.AngularStiffness28AS29"]]| AS|QAS|CAS| ✓| ✓|none (integer -4 to +4)|(% style="width:510px" %)Suggested values are between 0 to +4|(% style="text-align:center; width:113px" %)0

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| 2|[[**A**ngular **H**olding Stiffness>>||anchor="H15.AngularHoldStiffness28AH29"]]|AH|QAH|CAH| | ✓|none (integer -10 to +10)|(% style="width:510px" %) |(% style="text-align:center; width:113px" %)1

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| 3|[[**A**ngular **A**cceleration>>||anchor="H15b:AngularAcceleration28AA29"]]|AA|QAA|CAA| | ✓|degrees per second squared|(% style="width:510px" %)Increments of 10 degrees per second squared|(% style="text-align:center; width:113px" %)

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| 4|[[**A**ngular **D**eceleration>>||anchor="H15c:AngularDeceleration28AD29"]]|AD|QAD|CAD| | ✓|degrees per second squared|(% style="width:510px" %)Increments of 10 degrees per second squared|(% style="text-align:center; width:113px" %)

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| 5|[[**E**nable **M**otion Control>>||anchor="H15d:MotionControl28MC29"]]|EM|QEM| | | ✓|none|(% style="width:510px" %)EM0 to disable motion control, EM1 to enable|(% style="text-align:center; width:113px" %)

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| 6|[[**C**onfigure **L**ED **B**linking>>||anchor="H16b.ConfigureLEDBlinking28CLB29"]]| | | CLB| ✓| |none (integer from 0 to 63)|(% style="width:510px" %)0=No blinking, ; 63=Always blink; Blink while: 1=Limp; 2=Holding 4=Accel; 8=Decel; 16=Free 32=Travel;|(% style="text-align:center; width:113px" %)

== Details ==

====== __1. Limp (**L**)__ ======

Example: #5L<cr>

This action causes the servo to go "limp". The microcontroller will still be powered, but the motor will not. As an emergency safety feature, should the robot not be doing what it is supposed to or risks damage, use the broadcast ID to set all servos limp #254L<cr>.

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====== __2. Halt & Hold (**H**)__ ======

Example: #5H<cr>

This action overrides whatever the servo might be doing at the time the command is received (accelerating, moving continuously etc.) and causes it to stop immediately and hold that position.

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====== __3. Timed move (**T**)__ ======

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Example: #5P1500T2500<cr>

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Timed move can be used only as a modifier for a position (P) action. The units are in milliseconds, so a timed move of 2500 milliseconds would cause the servo to rotate from its current position to the desired position in 2.5 seconds. This command is in place to ensure backwards compatibility with the SSC-32 / 32U protocol.

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Note: If the calculated speed at which a servo must rotate for a timed move is greater than its maximum speed (which depends on voltage and load), then it will move at its maximum speed, and the time of the move may be longer than requested.

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====== __4. Speed (**S**)__ ======

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Example: #5P1500S750<cr>

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This command is a modifier only for a position (P) action and determines the speed of the move in microseconds per second. A speed of 750 microseconds would cause the servo to rotate from its current position to the desired position at a speed of 750 microseconds per second. This command is in place to ensure backwards compatibility with the SSC-32 / 32U protocol.

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====== __5. (Relative) Move in Degrees (**MD**)__ ======

Example: #5MD123<cr>

The relative move command causes the servo to read its current position and move the specified number of tenths of degrees in the corresponding position. For example if the servo is set to rotate CW (default) and an MD command of 123 is sent to the servo, it will cause the servo to rotate clockwise by 12.3 degrees. Negative commands would cause the servo to rotate in the opposite configured direction.

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====== __6. Origin Offset Action (**O**)__ ======

Example: #5O2400<cr>

This command allows you to temporarily change the origin of the servo in relation to the factory zero position. The setting will be lost upon servo reset / power cycle. Origin offset commands are not cumulative and always relate to factory zero. Note that for a given session, the O command overrides the CO command. In the first image, the origin at factory offset '0' (centered).

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[[image:LSS-servo-default.jpg]]

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In the second image, the origina, as well as the angular range (explained below) have been shifted by 240.0 degrees:

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[[image:LSS-servo-origin.jpg]]

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Origin Offset Query (**QO**)

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Example: #5QO<cr> Returns: *5QO-13

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This allows you to query the angle (in tenths of degrees) of the origin in relation to the factory zero position.

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Configure Origin Offset (**CO**)

Example: #5CO-24<cr>

This command allows you to change the origin of the servo in relation to the factory zero position in EEPROM. The setting will be saved upon servo reset / power cycle. Origin offset configuration commands are not cumulative and always relate to factory zero. The new origin is also used in RC mode.

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====== __7. Angular Range (**AR**)__ ======

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Example: #5AR1800<cr>

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This command allows you to temporarily change the total angular range of the servo in tenths of degrees. This applies to the Position in Pulse (P) command and RC mode. The default for (P) and RC mode is 1800 (180.0 degrees total, or ±90.0 degrees). In the first image,

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[[image:LSS-servo-default.jpg]]

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Here, the angular range has been restricted to 180.0 degrees, or -90.0 to +90.0. The center has remained unchanged.

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[[image:LSS-servo-ar.jpg]]

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The angular range action command (ex. #5AR1800<cr>) and origin offset action command (ex. #5O-1200<cr>) an be used to move both the center and limit the angular range:

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[[image:LSS-servo-ar-o-1.jpg]]

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Query Angular Range (**QAR**)

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Example: #5QAR<cr> might return *5AR2756

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Configure Angular Range (**CAR**)

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This command allows you to change the total angular range of the servo in tenths of degrees in EEPROM. The setting will be saved upon servo reset / power cycle.

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====== __8. Position in Pulse (**P**)__ ======

Example: #5P2334<cr>

The position in PWM pulses was retained in order to be backward compatible with the SSC-32 / 32U protocol. This relates the desired angle with an RC standard PWM pulse and is further explained in the SSC-32 and SSC-32U manuals found on Lynxmotion.com. Without any modifications to configuration considered, and a ±90.0 degrees standard range where 1500 microseconds is centered, a pulse of 2334 would set the servo to 165.1 degrees. Valid values for P are [500, 2500]. Values outside this range are corrected to end points.

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Query Position in Pulse (**QP**)

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Example: #5QP<cr> might return *5QP2334

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This command queries the current angular position in PWM "units". The user must take into consideration that the response includes any angular range and origin configurations in order to determine the actual angle.

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Valid values for QP are {-500, [500, 2500], -2500}. Values outside the [500, 2500] range are given a negative corresponding end point value to indicate they are out of bounds (note that if the servo is physically located at one of the endpoints, it may return a negative number if it is a fraction of a degree beyond the position).

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====== __9. Position in Degrees (**D**)__ ======

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Example: #5PD1456<cr>

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This moves the servo to an angle of 145.6 degrees, where the center (0) position is centered. Negative values (ex. -176 representing -17.6 degrees) are used. A full circle would be from -1800 to 1800 degrees. A value of 2700 would be the same angle as -900, except the servo would move in a different direction.

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Larger values are permitted and allow for multi-turn functionality using the concept of virtual position.

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Query Position in Degrees (**QD**)

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Example: #5QD<cr> might return *5QD132<cr>

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This means the servo is located at 13.2 degrees.

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====== __10. Wheel Mode in Degrees (**WD**)__ ======

Ex: #5WD900<cr>

This command sets the servo to wheel mode where it will rotate in the desired direction at the selected speed. The example above would have the servo rotate at 90.0 degrees per second clockwise (assuming factory default configurations).

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Query Wheel Mode in Degrees (**QWD**)

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Ex: #5QWD<cr> might return *5QWD900<cr>

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The servo replies with the angular speed in tenths of degrees per second. A negative sign would indicate the opposite direction (for factory default a negative value would be counter clockwise).

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====== __11. Wheel Mode in RPM (**WR**)__ ======

Ex: #5WR40<cr>

This command sets the servo to wheel mode where it will rotate in the desired direction at the selected rpm. Wheel mode (a.k.a. "continuous rotation") has the servo operate like a geared DC motor. The servo's maximum rpm cannot be set higher than its physical limit at a given voltage. The example above would have the servo rotate at 40 rpm clockwise (assuming factory default configurations).

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Query Wheel Mode in RPM (**QWR**)

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Ex: #5QWR<cr> might return *5QWR40<cr>

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The servo replies with the angular speed in rpm. A negative sign would indicate the opposite direction (for factory default a negative value would be counter clockwise).

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====== __12. Speed in Degrees (**SD**)__ ======

Ex: #5SD1800<cr>

This command sets the servo's maximum speed for action commands in tenths of degrees per second for that session. In the example above, the servo's maximum speed for that session would be set to 180.0 degrees per second. Therefore maximum speed for actions can be set "on the fly". The servo's maximum speed cannot be set higher than its physical limit at a given voltage. SD overrides CSD (described below) for that session. Upon reset or power cycle, the servo reverts to the value associated with CSD as described below. Note that SD and SR (described below) are effectively the same, but allow the user to specify the speed in either unit. The last command (either SR or SD) is what the servo uses for that session.

330

331

Query Speed in Degrees (**QSD**)

332

333

Ex: #5QSD<cr> might return *5QSD1800<cr>

334

335

By default QSD will return the current session value, which is set to the value of CSD as reset/power cycle and changed whenever a SD/SR command is processed.

336

If #5QSD1<cr> is sent, the configured maximum speed (CSD value) will be returned instead. You can also query the current speed using "2" and the current target travel speed using "3". See the table below for an example:

337

338

|**Command sent**|**Returned value (1/10 °)**

339

|ex: #5QSD<cr>|Session value for maximum speed (set by latest SD/SR command)

340

|ex: #5QSD1<cr>|Configured maximum speed (set by CSD/CSR)

341

|ex: #5QSD2<cr>|Instantaneous speed (same as QWD)

342

|ex: #5QSD3<cr>|Target travel speed

343

344

Configure Speed in Degrees (**CSD**)

Ex: #5CSD1800<cr>

Using the CSD command sets the servo's maximum speed which is saved in EEPROM. In the example above, the servo's maximum speed will be set to 180.0 degrees per second. When the servo is powered on (or after a reset), the CSD value is used. Note that CSD and CSR (described below) are effectively the same, but allow the user to specify the speed in either unit. The last command (either CSR or CSD) is what the servo uses for that session.

349

350

====== __13. Speed in RPM (**SR**)__ ======

Ex: #5SD45<cr>

This command sets the servo's maximum speed for action commands in rpm for that session. In the example above, the servo's maximum speed for that session would be set to 45rpm. Therefore maximum speed for actions can be set "on the fly". The servo's maximum speed cannot be set higher than its physical limit at a given voltage. SD overrides CSD (described below) for that session. Upon reset or power cycle, the servo reverts to the value associated with CSD as described below. Note that SD (described above) and SR are effectively the same, but allow the user to specify the speed in either unit. The last command (either SR or SD) is what the servo uses for that session.

355

356

Query Speed in Degrees (**QSR**)

357

358

Ex: #5QSR<cr> might return *5QSR45<cr>

359

360

By default QSR will return the current session value, which is set to the value of CSR as reset/power cycle and changed whenever a SD/SR command is processed.

361

If #5QSR1<cr> is sent, the configured maximum speed (CSR value) will be returned instead. You can also query the current speed using "2" and the current target travel speed using "3". See the table below for an example:

362

363

|**Command sent**|**Returned value (1/10 °)**

364

|ex: #5QSR<cr>|Session value for maximum speed (set by latest SD/SR command)

365

|ex: #5QSR1<cr>|Configured maximum speed (set by CSD/CSR)

366

|ex: #5QSR2<cr>|Instantaneous speed (same as QWR)

367

|ex: #5QSR3<cr>|Target travel speed

368

369

Configure Speed in RPM (**CSR**)

Ex: #5CSR45<cr>

Using the CSR command sets the servo's maximum speed which is saved in EEPROM. In the example above, the servo's maximum speed will be set to 45rpm. When the servo is powered on (or after a reset), the CSR value is used. Note that CSD and CSR are effectively the same, but allow the user to specify the speed in either unit. The last command (either CSR or CSD) is what the servo uses for that session.

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375

====== __14. Angular Stiffness (**AS**)__ ======

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The servo's rigidity / angular stiffness can be thought of as (though not identical to) a damped spring in which the value affects the stiffness and embodies how much, and how quickly the servo tried keep the requested position against changes.

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379

A positive value of "angular stiffness":

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381

* The more torque will be applied to try to keep the desired position against external input / changes

382

* The faster the motor will reach its intended travel speed and the motor will decelerate faster and nearer to its target position

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384

A negative value on the other hand:

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* Causes a slower acceleration to the travel speed, and a slower deceleration

387

* Allows the target position to deviate more from its position before additional torque is applied to bring it back

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The default value is zero and the effect becomes extreme by -4, +4. There are no units, only integers between -4 to 4. Greater values produce increasingly erratic behavior.

Ex: #5AS-2<cr>

This reduces the angular stiffness to -2 for that session, allowing the servo to deviate more around the desired position. This can be beneficial in many situations such as impacts (legged robots) where more of a "spring" effect is desired. Upon reset, the servo will use the value stored in memory, based on the last configuration command.

Ex: #5QAS<cr>

Queries the value being used.

Ex: #5CAS<cr>

Writes the desired angular stiffness value to memory.

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403

====== __15. Angular Hold Stiffness (**AH**)__ ======

404

405

The angular holding stiffness determines the servo's ability to hold a desired position under load. Values can be from -10 to 10, with the default being 0. Note that negative values mean the final position can be easily deflected.

Ex: #5AH3<cr>

This sets the holding stiffness for servo #5 to 3 for that session.

410

411

Query Angular Hold Stiffness (**QAH**)

412

413

Ex: #5QAH<cr> might return *5QAH3<cr>

414

415

This returns the servo's angular holding stiffness value.

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417

Configure Angular Hold Stiffness (**CAH**)

Ex: #5CAH2<cr>

This writes the angular holding stiffness of servo #5 to 2 to EEPROM

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423

====== __15b: Angular Acceleration (**AA**)__ ======

424

425

{More details to come}

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427

====== __15c: Angular Deceleration (**AD**)__ ======

428

429

{More details to come}

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431

====== __15d: Motion Control (**EM**)__ ======

432

433

{More details to come}

434

435

====== __16. RGB LED (**LED**)__ ======

Ex: #5LED3<cr>

This action sets the servo's RGB LED color for that session.The LED can be used for aesthetics, or (based on user code) to provide visual status updates. Using timing can create patterns.

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441

0=OFF 1=RED 2=GREEN 3= BLUE 4=YELLOW 5=CYAN 6= 7=MAGENTA, 8=WHITE

442

443

Query LED Color (**QLED**)

444

445

Ex: #5QLED<cr> might return *5QLED5<cr>

446

447

This simple query returns the indicated servo's LED color.

448

449

Configure LED Color (**CLED**)

450

451

Configuring the LED color via the CLED command sets the startup color of the servo after a reset or power cycle. Note that it also changes the session's LED color immediately as well.

452

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====== __16b. Configure LED Blinking (**CLB**)__ ======

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455

This command allows you to control when the RGB LED will blink the user set color (see [[16. RGB LED>>||anchor="H16.RGBLED28LED29"]] for details).

456

You can turn on or off blinking for various LSS status. Here is the list and their associated value: 0=No blinking, ; 63=Always blink; Blink while: 1=Limp; 2=Holding 4=Accel; 8=Decel; 16=Free 32=Travel;

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To set blinking, use CLB with the value of your choosing. To activate blinking in multiple status, simply add together the values of the corresponding status. See examples below:

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460

Ex: #5CLB0<cr> to turn off all blinking (LED always solid)

461

Ex: #5CLB1<cr> only blink when limp

462

Ex: #5CLB2<cr> only blink when holding

463

Ex: #5CLB12<cr> only blink when accel or decel

464

Ex: #5CLB48<cr> only blink when free or travel

465

Ex: #5CLB63<cr> blink in all status

466

467

====== __17. Identification Number__ ======

468

469

A servo's identification number cannot be set "on the fly" and must be configured via the CID command described below. The factory default ID number for all servos is 0. Since smart servos are intended to be daisy chained, in order to respond differently from one another, the user must set different identification numbers. Servos with the same ID and baud rate will all receive and react to the same commands.

470

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Query Identification (**QID**)

472

473

EX: #254QID<cr> might return *QID5<cr>

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When using the query ID command, it is best to only have one servo connected and thus receive only one reply using the broadcast command (ID 254). Alternatively, pushing the button upon startup and temporarily setting the servo ID to 255 will still result in the servo responding with its "real" ID.

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Configure ID (**CID**)

Ex: #4CID5<cr>

Setting a servo's ID in EEPROM is done via the CID command. All servos connected to the same serial bus will be assigned that ID. In most situations each servo must be set a unique ID, which means each servo must be connected individually to the serial bus and receive a unique CID number. It is best to do this before the servos are added to an assembly. Numbered stickers are provided to distinguish each servo after their ID is set, though you are free to use whatever alternative method you like.

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====== __18. Baud Rate__ ======

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A servo's baud rate cannot be set "on the fly" and must be configured via the CB command described below. The factory default baud rate for all servos is 9600. Since smart servos are intended to be daisy chained, in order to respond to the same serial bus, all servos in that project should ideally be set to the same baud rate. Setting different baud rates will have the servos respond differently and may create issues. Available baud rates are: 9.6 kbps, 19.2 kbps, 38.4 kbps, 57.6 kbps, 115.2 kbps, 230.4 kbps, 250.0 kbps, 460.8 kbps, 500.0 kbps, 750.0 kbps*, 921.6 kbps*. Servos are shipped with a baud rate set to 9600. The baud rates are currently restricted to those above.

486

\*: Current tests reveal baud rates above 500 kbps are unstable and can cause timeouts. Please keep this in mind if using those / testing them out.

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Query Baud Rate (**QB**)

489

490

Ex: #5QB<cr> might return *5QB9600<cr>

491

492

Querying the baud rate is used simply to confirm the CB configuration command before the servo is power cycled.

493

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Configure Baud Rate (**CB**)

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496

Important Note: the servo's current session retains the given baud rate and the new baud rate will only be in place when the servo is power cycled.

Ex: #5CB9600<cr>

Sending this command will change the baud rate associated with servo ID 5 to 9600 bits per second.

501

502

====== __19. Gyre Rotation Direction__ ======

503

504

"Gyre" is defined as a circular course or motion. The effect of changing the gyre direction is as if you were to use a mirror image of a circle. CW = 1; CCW = -1. The factory default is clockwise (CW).

505

506

{images showing before and after with AR and Origin offset}

507

508

Query Gyre Direction (**QG**)

509

510

Ex: #5QG<cr> might return *5QG-1<cr>

511

512

The value returned above means the servo is in a counter-clockwise gyration.

513

514

Configure Gyre (**CG**)

Ex: #5CG-1<cr>

This changes the gyre direction as described above and also writes to EEPROM.

519

520

====== __20. First / Initial Position (pulse)__ ======

521

522

In certain cases, a user might want to have the servo move to a specific angle upon power up. We refer to this as "first position". The factory default has no first position value stored in EEPROM and therefore upon power up, the servo remains limp until a position (or hold command) is assigned. FP and FD are different in that FP is used for RC mode only, whereas FD is used for smart mode only.

523

524

Query First Position in Pulses (**QFP**)

525

526

Ex: #5QFP<cr> might return *5QFP1550<cr>

527

528

The reply above indicates that servo with ID 5 has a first position pulse of 1550 microseconds. If no first position has been set, servo will respond with DIS ("disabled").

529

530

Configure First Position in Pulses (**CFP**)

Ex: #5CP1550<cr>

This configuration command means the servo, when set to RC mode, will immediately move to an angle equivalent to having received an RC pulse of 1550 microseconds upon power up. Sending a CFP command without a number results in the servo remaining limp upon power up (i.e. disabled).

535

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====== __21. First / Initial Position (Degrees)__ ======

537

538

In certain cases, a user might want to have the servo move to a specific angle upon power up. We refer to this as "first position". The factory default has no first position value stored in EEPROM and therefore upon power up, the servo remains limp until a position (or hold command) is assigned. FP and FD are different in that FP is used for RC mode only, whereas FD is used for smart mode only.

539

540

Query First Position in Degrees (**QFD**)

541

542

Ex: #5QFD<cr> might return *5QFD64<cr>

543

544

The reply above indicates that servo with ID 5 has a first position pulse of 1550 microseconds.

545

546

Configure First Position in Degrees (**CFD**)

Ex: #5CD64<cr>

This configuration command means the servo, when set to smart mode, will immediately move to 6.4 degrees upon power up. Sending a CFD command without a number results in the servo remaining limp upon power up.

551

552

====== __22. Query Target Position in Degrees (**QDT**)__ ======

553

554

Ex: #5QDT<cr> might return *5QDT6783<cr>

555

556

The query target position command returns the target angle during and after an action which results in a rotation of the servo horn. In the example above, the servo is rotating to a virtual position of 678.3 degrees. Should the servo not have a target position or be in wheel mode, it will respond without a number (Ex: *5QDT<cr>).

557

558

====== __23. Query Model String (**QMS**)__ ======

559

560

Ex: #5QMS<cr> might return *5QMSLSS-HS1cr>

561

562

This reply means the servo model is LSS-HS1, meaning a high speed servo, first revision.

563

564

====== __23b. Query Model (**QM**)__ ======

565

566

Ex: #5QM<cr> might return *5QM68702699520cr>

567

568

This reply means the servo model is 0xFFF000000 or 100, meaning a high speed servo, first revision.

569

570

====== __24. Query Serial Number (**QN**)__ ======

571

572

Ex: #5QN<cr> might return *5QN~_~_<cr>

573

574

The number in the response is the servo's serial number which is set and cannot be changed.

575

576

====== __25. Query Firmware (**QF**)__ ======

577

578

Ex: #5QF<cr> might return *5QF11<cr>

579

580

The integer in the reply represents the firmware version with one decimal, in this example being 1.1

581

582

====== __26. Query Status (**Q**)__ ======

583

584

Ex: #5Q<cr> might return *5Q6<cr>, which indicates the motor is holding a position.

585

586

|*Value returned|**Status**|**Detailed description**

587

|ex: *5Q0<cr>|Unknown|LSS is unsure

588

|ex: *5Q1<cr>|Limp|Motor driving circuit is not powered and horn can be moved freely

589

|ex: *5Q2<cr>|Free moving|Motor driving circuit is not powered and horn can be moved freely

590

|ex: *5Q3<cr>|Accelerating|Increasing speed from rest (or previous speeD) towards travel speed

591

|ex: *5Q4<cr>|Traveling|Moving at a stable speed

592

|ex: *5Q5<cr>|Decelerating|Decreasing from travel speed towards final position.

593

|ex: *5Q6<cr>|Holding|Keeping current position

594

|ex: *5Q7<cr>|Stepping|Special low speed mode to maintain torque

595

|ex: *5Q8<cr>|Outside limits|{More details coming soon}

596

|ex: *5Q9<cr>|Stuck|Motor cannot perform request movement at current speed setting

597

|ex: *5Q10<cr>|Blocked|Similar to stuck, but the motor is at maximum duty and still cannot move (i.e.: stalled)

598

599

====== __27. Query Voltage (**QV**)__ ======

600

601

Ex: #5QV<cr> might return *5QV11200<cr>

602

603

The number returned has one decimal, so in the case above, servo with ID 5 has an input voltage of 11.2V (perhaps a three cell LiPo battery).

604

605

====== __28. Query Temperature (**QT**)__ ======

606

607

Ex: #5QT<cr> might return *5QT564<cr>

608

609

The units are in tenths of degrees Celcius, so in the example above, the servo's internal temperature is 56.4 degrees C. To convert from degrees Celcius to degrees Farenheit, multiply by 1.8 and add 32. Therefore 56.4C = 133.52F.

610

611

====== __29. Query Current (**QC**)__ ======

612

613

Ex: #5QC<cr> might return *5QC140<cr>

614

615

The units are in milliamps, so in the example above, the servo is consuming 140mA, or 0.14A.

616

617

====== __30. RC Mode (**CRC**)__ ======

618

619

This command puts the servo into RC mode (position or continuous), where it will only respond to RC pulses. Note that because this is the case, the servo will no longer accept serial commands. The servo can be placed back into smart mode by using the button menu.

620

621

|**Command sent**|**Note**

622

|ex: #5CRC<cr>|Stay in smart mode.

623

|ex: #5CRC1<cr>|Change to RC position mode.

624

|ex: #5CRC2<cr>|Change to RC continuous (wheel) mode.

625

|ex: #5CRC*<cr>|Where * is any number or value. Stay in smart mode.

EX: #5CRC<cr>

====== __31. RESET__ ======

630

631

Ex: #5RESET<cr> or #5RS<cr>

632

633

This command does a "soft reset" (no power cycle required) and reverts all commands to those stored in EEPROM (i.e. configuration commands).

634

635

====== __32. DEFAULT & CONFIRM__ ======

Ex: #5DEFAULT<cr>

This command sets in motion the reset all values to the default values included with the version of the firmware installed on that servo. The servo then waits for the CONFIRM command. Any other command received will cause the servo to exit the DEFAULT function.

640

641

EX: #5DEFAULT<cr> followed by #5CONFIRM<cr>

642

643

Since it it not common to have to restore all configurations, a confirmation command is needed after a firmware command is sent. Should any command other than CONFIRM be received by the servo after the firmware command has been received, it will leave the firmware action.

644

645

Note that after the CONFIRM command is sent, the servo will automatically perform a RESET.

646

647

====== __33. UPDATE & CONFIRM__ ======

Ex: #5UPDATE<cr>

This command sets in motion the equivalent of a long button press when the servo is not powered in order to enter firmware update mode. This is useful should the button be broken or inaccessible. The servo then waits for the CONFIRM command. Any other command received will cause the servo to exit the UPDATE function.

652

653

EX: #5UPDATE<cr> followed by #5CONFIRM<cr>

654

655

Since it it not common to have to update firmware, a confirmation command is needed after an UPDATE command is sent. Should any command other than CONFIRM be received by the servo after the firmware command has been received, it will leave the firmware action.

656

657

Note that after the CONFIRM command is sent, the servo will automatically perform a RESET.

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