Changes for page LSS Communication Protocol

Last modified by Eric Nantel on 2025/06/06 07:47

From version < 54.1 >

edited by RB1
on 2018/09/12 11:36

To version < 64.18 >

edited by RB1
on 2018/11/19 09:32

< >

Change comment: There is no comment for this version

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@@ -1,6
          +1,10 @@
++{{toc depth="3"/}}
++
++= Protocol concepts =
++#anchor0001
  The Lynxmotion Smart Servo (LSS) protocol was created in order to be as simple and straightforward as possible from a user perspective, while at the same time trying to stay compact and robust yet highly versatile. Almost everything one might expect to be able to configure for a smart servo motor is available.
--=== Session ===
++== Session ==
  A "session" is defined as the time between when the servo is powered ON to when it is powered OFF or reset.
@@ -39,13
          +39,9 @@
  Results in the servo rotating from the current angular position to a pulse position of 1456 in 1263 milliseconds.
--Modified commands are command specific.
++Action modifiers can only be used with certain commands.
  )))
--(((
--
--)))
--
  == Configuration Commands ==
  Configuration commands affect the servo's current session* but unlike action commands, configuration commands are written to EEPROM and are retained even if the servo loses power (therefore NOT session specific). Not all action commands have a corresponding configuration and vice versa. Certain configurations are retained for when the servo is used in RC model. More information can be found on the [[LSS - RC PWM page>>doc:LSS - Overview (DEV).LSS - RC PWM.WebHome]].
@@ -105,6
          +105,30 @@
  #5QSR<cr> would return *5QSR4<cr> which represents the value for that session.
  #5QSR1<cr> would return *5QSR20<cr> which represents the value in EEPROM
++
++=== Virtual Angular Position ===
++
++{In progress}
++
++A "virtual position" is one which allows for multiple rotations of the output horn, moving the center position and more. The "absolute position" would be the angle of the output shaft with respect to 360.0 degrees.
++
++[[image:LSS-servo-positions.jpg]]
++
++Example: Gyre direction / rotation is positive (clockwise), and origin offset has not been modified. Each square represents 30 degrees.
++
++#1D-300<cr> The servo is sent a command to move to -30.0 degrees (green arrow)
++
++#1D2100<cr> This second position command is sent to the servo, which moves it to 210.0 degrees (orange arrow)
++
++#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,  stopping at an absolute position of 60.0 degrees (420.0-360.0), with a virtual position of -420.0 degrees.
++
++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.
++
++#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.
++
++#1D3300<cr> would cause the servo to rotate from 480.0 degrees to 330.0 degrees (yellow arrow).
++
++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).
  )))
  = Command List =
@@ -126,7
          +126,10 @@
  | 12|Max **S**peed in **D**egrees| SD| QSD| CSD| ✓| ✓| tenths of degrees per second (ex 248 = 24.8 degrees per second)|QSD: Add modifier "2" for instantaneous speed
  | 13|Max **S**peed in **R**PM| SR| QSR| CSR| ✓| ✓| rpm|QSR: Add modifier "2" for instantaneous speed
  | 14|**A**ngular **S**tiffness| AS| QAS| CAS| ✓| ✓|none|-4 to +4, but suggested values are between 0 to +4
--| 15|//N/A (removed)//| | | | | | |
++| 15|**A**ngular **H**olding Stiffness|AH|QAH|CAH| | ✓|none|-10 to +10, with default as 0.
++|15b|**A**ngular **A**cceleration|AA|QAA|CAA| | ✓|degrees per second squared|Increments of 10 degrees per second squared
++|15c|**A**ngular **D**eceleration|AD|QAD|CAD| | ✓|degrees per second squared|Increments of 10 degrees per second squared
++|15d|**M**otion **C**ontrol|MC|QMC| | | ✓|none|MC0 to disable motion control, MC1 to enable. Session specific
  | 16|**LED** Color| LED| QLED| CLED| ✓| ✓| none (integer from 1 to 8)|0=OFF 1=RED 2=GREEN 3= BLUE 4=YELLOW 5=CYAN 6=MAGENTA, 7=WHITE
  | 17|**ID** #| | QID| CID| | ✓| none (integer from 0 to 250)|Note: ID 254 is a "broadcast" which all servos respond to
  | 18|**B**aud rate| B| QB| CB| | ✓| none (integer)|
@@ -134,54
          +134,57 @@
  | 20|**F**irst Position (**P**ulse)| | QFP|CFP | ✓| ✓| none |
  | 21|**F**irst Position (**D**egrees)| | QFD|CFD| ✓| ✓| none |
  | 22|**T**arget (**D**egree) **P**osition| | QDT| | | ✓| tenths of degrees (ex 325 = 32.5 degrees; 91 = 9.1 degrees)|
--| 23|**M**odel| | QM| | | | none (integer)|
++| 23|**M**odel **String**| | QMS| | | | none (string)| Recommended to determine the model|
++| 23b|**M**odel| | QM| | | | none (integer)| Returns a raw value representing the three model inputs (36 bit)|
  | 24|Serial **N**umber| | QN| | | | none (integer)|
  | 25|**F**irmware version| | QF| | | | none (integer)|
  | 26|**Q**uery (general status)| | Q| | | ✓| none (integer from 1 to 8)| See command description for details
--| 27|**V**oltage| | QV| | | ✓| tenths of volt (ex 113 = 11.3V; 92 = 9.2V)|
--| 28|**T**emperature| | QT| | | ✓| degrees Celsius|Max temp before error: 85°C (servo goes limp)
--| 29|**C**urrent| | QC| | | ✓| tenths of Amps (ex 2 = 0.2A)|
--| 30|**RC** Mode| | |CRC| |✓| |(((
++| 27|**V**oltage| | QV| | | ✓| millivolts (ex 5936 = 5936mV = 5.936V)|
++| 28|**T**emperature| | QT| | | ✓| tenths of degrees Celsius|Max temp before error: 85°C (servo goes limp)
++| 29|**C**urrent| | QC| | | ✓| milliamps (ex 200 = 0.2A)|
++| 30|**RC** Mode| | |CRC| |✓|none|(((
  CRC: Add modifier "1" for RC-position mode.
  CRC: Add modifier "2" for RC-wheel mode.
  Any other value for the modifier results in staying in smart mode.
  Puts the servo into RC mode. To revert to smart mode, use the button menu.
  )))
--| | | | | | | | |
++|31|**RESET**| | | | | ✓|none|Soft reset. See command for details.
++|32|**DEFAULT**| | | | |✓|none|Revert to firmware default values. See command for details
++|33|**UPDATE**| | | | |✓|none|Update firmware. See command for details.
--= Details =
++== Details ==
--__1. Limp (**L**)__
++====== __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>.
--__2. Halt & Hold (**H**)__
++====== __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.
--__3. Timed move (**T**)__
++====== __3. Timed move (**T**)__ ======
  Example: #5P1500T2500<cr>
  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.
--__4. Speed (**S**)__
++====== __4. Speed (**S**)__ ======
  Example: #5P1500S750<cr>
  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.
--__5. (Relative) Move in Degrees (**MD**)__
++====== __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.
--__6. Origin Offset Action (**O**)__
++====== __6. Origin Offset Action (**O**)__ ======
  Example: #5O2400<cr>
@@ -205,7
          +205,7 @@
  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.
--__7. Angular Range (**AR**)__
++====== __7. Angular Range (**AR**)__ ======
  Example: #5AR1800<cr>
@@ -229,7
          +229,7 @@
  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.
--__8. Position in Pulse (**P**)__
++====== __8. Position in Pulse (**P**)__ ======
  Example: #5P2334<cr>
@@ -242,7
          +242,7 @@
  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.
  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).
--__9. Position in Degrees (**D**)__
++====== __9. Position in Degrees (**D**)__ ======
  Example: #5PD1456<cr>
@@ -256,7
          +256,7 @@
  This means the servo is located at 13.2 degrees.
--__10. Wheel Mode in Degrees (**WD**)__
++====== __10. Wheel Mode in Degrees (**WD**)__ ======
  Ex: #5WD900<cr>
@@ -268,7
          +268,7 @@
  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).
--__11. Wheel Mode in RPM (**WR**)__
++====== __11. Wheel Mode in RPM (**WR**)__ ======
  Ex: #5WR40<cr>
@@ -280,7
          +280,7 @@
  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).
--__12. Speed in Degrees (**SD**)__
++====== __12. Speed in Degrees (**SD**)__ ======
  Ex: #5SD1800<cr>
@@ -305,7
          +305,7 @@
  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.
--__13. Speed in RPM (**SR**)__
++====== __13. Speed in RPM (**SR**)__ ======
  Ex: #5SD45<cr>
@@ -330,7
          +330,7 @@
  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.
--__14. Angular Stiffness (AS)__
++====== __14. Angular Stiffness (**AS**)__ ======
  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.
@@ -358,12
          +358,40 @@
  Writes the desired angular stiffness value to memory.
--__15. N/A (removed)__
++====== __15. Angular Hold Stiffness (**AH**)__ ======
--This command has been removed.
++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.
--__16. RGB LED (**LED**)__
++Ex: #5AH3<cr>
++This sets the holding stiffness for servo #5 to 3 for that session.
++
++Query Angular Hold Stiffness (**QAH**)
++
++Ex: #5QAH<cr> might return *5QAH3<cr>
++
++This returns the servo's angular holding stiffness value.
++
++Configure Angular Hold Stiffness (**CAH**)
++
++Ex: #5CAH2<cr>
++
++This writes the angular holding stiffness of servo #5 to 2 to EEPROM
++
++====== __15b: Angular Acceleration (**AA**)__ ======
++
++{More details to come}
++
++====== __15c: Angular Deceleration (**AD**)__ ======
++
++{More details to come}
++
++====== __15d: Motion Control (**MC**)__ ======
++
++{More details to come}
++
++====== __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.
@@ -380,7
          +380,7 @@
  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.
--__17. Identification Number__
++====== __17. Identification Number__ ======
  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.
@@ -396,7
          +396,7 @@
  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.
--__18. Baud Rate__
++====== __18. Baud Rate__ ======
  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.
  \*: 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.
@@ -413,7
          +413,7 @@
  Sending this command will change the baud rate associated with servo ID 5 to 9600 bits per second.
--__19. Gyre Rotation Direction__
++====== __19. Gyre Rotation Direction__ ======
  "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).
@@ -431,7
          +431,7 @@
  This changes the gyre direction as described above and also writes to EEPROM.
--__20. First / Initial Position (pulse)__
++====== __20. First / Initial Position (pulse)__ ======
  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.
@@ -447,7
          +447,7 @@
  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).
--__21. First / Initial Position (Degrees)__
++====== __21. First / Initial Position (Degrees)__ ======
  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.
@@ -463,31
          +463,37 @@
  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.
--__22. Query Target Position in Degrees (**QDT**)__
++====== __22. Query Target Position in Degrees (**QDT**)__ ======
  Ex: #5QDT<cr> might return *5QDT6783<cr>
  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>).
--__23. Query Model (**QM**)__
++====== __23. Query Model String (**QMS**)__ ======
--Ex: #5QM<cr> might return *5QM11<cr>
++Ex: #5QMS<cr> might return *5QMSLSS-HS1cr>
--This reply means the servo model is 1.1, meaning high speed servo, first revision. 1=HS (high speed) 2=ST (standard) 3=HT (high torque)
++This reply means the servo model  is LSS-HS1, meaning a high speed servo, first revision.
--__24. Query Serial Number (**QN**)__
++====== __23b. Query Model (**QM**)__ ======
++Ex: #5QM<cr> might return *5QM68702699520cr>
++
++This reply means the servo model is 0xFFF000000 or 100, meaning a high speed servo, first revision.
++
++====== __24. Query Serial Number (**QN**)__ ======
++
  Ex: #5QN<cr> might return *5QN~_~_<cr>
  The number in the response is the servo's serial number which is set and cannot be changed.
--__25. Query Firmware (**QF**)__
++====== __25. Query Firmware (**QF**)__ ======
  Ex: #5QF<cr> might return *5QF11<cr>
  The integer in the reply represents the firmware version with one decimal, in this example being 1.1
--__26. Query Status (**Q**)__
++====== __26. Query Status (**Q**)__ ======
  Ex: #5Q<cr> might return *5Q6<cr>, which indicates the motor is holding a position.
@@ -504,25
          +504,25 @@
  |ex: *5Q9<cr>|Stuck|Motor cannot perform request movement at current speed setting
  |ex: *5Q10<cr>|Blocked|Similar to stuck, but the motor is at maxiumum duty and still cannot move (i.e.: stalled)
--__27. Query Voltage (**QV**)__
++====== __27. Query Voltage (**QV**)__ ======
--Ex: #5QV<cr> might return *5QV112<cr>
++Ex: #5QV<cr> might return *5QV11200<cr>
  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).
--__28. Query Temperature (**QT**)__
++====== __28. Query Temperature (**QT**)__ ======
  Ex: #5QT<cr> might return *5QT564<cr>
  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.
--__29. Query Current (**QC**)__
++====== __29. Query Current (**QC**)__ ======
  Ex: #5QC<cr> might return *5QC140<cr>
  The units are in milliamps, so in the example above, the servo is consuming 140mA, or 0.14A.
--__30. RC Mode (**CRC**)__
++====== __30. RC Mode (**CRC**)__ ======
  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.
@@ -534,13
          +534,13 @@
  EX: #5CRC<cr>
--__**RESET**__
++====== __31. RESET__ ======
  Ex: #5RESET<cr> or #5RS<cr>
  This command does a "soft reset" (no power cycle required) and reverts all commands to those stored in EEPROM (i.e. configuration commands).
--**__DEFAULT __**__& **CONFIRM**__
++====== __32. DEFAULT & CONFIRM__ ======
  Ex: #5DEFAULT<cr>
@@ -552,7
          +552,7 @@
  Note that after the CONFIRM command is sent, the servo will automatically perform a RESET.
--**__UPDATE __**__& **CONFIRM**__
++====== __33. UPDATE & CONFIRM__ ======
  Ex: #5UPDATE<cr>
@@ -563,28
          +563,3 @@
  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.
  Note that after the CONFIRM command is sent, the servo will automatically perform a RESET.
--
--=== Virtual Angular Position ===
--
--{In progress}
--
--A "virtual position" is one which allows for multiple rotations of the output horn, moving the center position and more. The "absolute position" would be the angle of the output shaft with respect to 360.0 degrees.
--
--[[image:LSS-servo-positions.jpg]]
--
--Example: Gyre direction / rotation is positive (clockwise), and origin offset has not been modified. Each square represents 30 degrees.
--
--#1D-300<cr> The servo is sent a command to move to -30.0 degrees (green arrow)
--
--#1D2100<cr> This second position command is sent to the servo, which moves it to 210.0 degrees (orange arrow)
--
--#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,  stopping at an absolute position of 60.0 degrees (420.0-360.0), with a virtual position of -420.0 degrees.
--
--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.
--
--#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.
--
--#1D3300<cr> would cause the servo to rotate from 480.0 degrees to 330.0 degrees (yellow arrow).
--
--
--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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