Examples

Practical LispBM script examples for motor control, sensor reading, CAN communication, and GPIO on VESC.

The following examples demonstrate common patterns for LispBM scripting on VESC. Each example is a complete, runnable script unless otherwise noted. Copy them into the VESC Tool scripting editor and upload to try them out.

VESC Tool ships with a built-in collection of example scripts accessible from the scripting editor menu. These examples are a good starting point for many common tasks.

Simple loop with status printing

The most basic VESC script structure: an initialization block followed by an infinite loop that periodically prints status and resets the motor timeout.

; Print firmware version and hardware name on startup
(print (sysinfo 'fw-ver))
(print (sysinfo 'hw-name))

; Main loop: print input voltage every 500 ms
(loopwhile t
  (progn
    (print (str-from-n (get-vin) "Vin: %.2f V"))
    (sleep 0.5)))

Blinking AUX output

Toggle the AUX1 output on and off at 1 Hz. This is the VESC equivalent of a “blink LED” example.

; AUX output mode must be set to Unused in motor settings
(define state 0)

(loopwhile t
  (progn
    (set-aux 1 state)
    (setvar 'state (if (= state 0) 1 0))
    (sleep 0.5)))

Reading motor RPM and reacting

Read the motor RPM and apply different behavior depending on the speed.

(defun handle-speed (rpm)
  (cond
    ((< (abs rpm) 100)
     (print "Motor stopped"))
    ((< (abs rpm) 2000)
     (print (str-from-n rpm "Low speed: %.0f RPM")))
    (t
     (print (str-from-n rpm "High speed: %.0f RPM")))))

(loopwhile t
  (progn
    (handle-speed (get-rpm))
    (sleep 0.2)))

Controlling motor speed with set-duty

Ramp the motor duty cycle from 0 to 30% over 3 seconds, hold it, then brake.

; Ramp up over 3 seconds
(looprange i 0 30
  (progn
    (set-duty (/ i 100.0))
    (timeout-reset)
    (sleep 0.1)))

; Hold at 30% for 2 seconds
(define t-start (systime))
(loopwhile (< (secs-since t-start) 2.0)
  (progn
    (set-duty 0.3)
    (timeout-reset)
    (sleep 0.01)))

; Brake
(set-brake 5.0)
(sleep 1.0)

; Release
(set-current 0.0)
(print "Done")

Always call (timeout-reset) at least once per second whenever the motor is running from a script. If the script stops calling it — for example due to a crash — the motor will automatically stop after the timeout period configured in App Settings → General.

RPM control with soft start

Use set-rpm to drive a motor to a target speed, reading configuration to stay within safe limits.

(define max-erpm (conf-get 'l-max-erpm))
(define target-rpm (min 3000.0 max-erpm))

(print (str-from-n max-erpm "Max ERPM from config: %.0f"))
(print (str-from-n target-rpm "Targeting: %.0f RPM"))

(loopwhile t
  (progn
    (set-rpm target-rpm)
    (timeout-reset)
    (print (str-from-n (get-rpm) "Current RPM: %.0f"))
    (sleep 0.05)))

Reading configuration values

Inspect key motor configuration parameters at startup. Useful for debugging or adapting script behavior to the configured hardware.

(define print-conf (lambda (sym label)
  (print (str-merge label (str-from-n (conf-get sym) " %.2f")))))

(print-conf 'l-current-max     "Max current (A): ")
(print-conf 'l-current-min     "Min current (A): ")
(print-conf 'l-max-erpm        "Max ERPM:        ")
(print-conf 'l-max-vin         "Max voltage (V): ")
(print-conf 'si-motor-poles    "Motor poles:     ")
(print-conf 'si-gear-ratio     "Gear ratio:      ")
(print-conf 'si-wheel-diameter "Wheel dia (m):   ")
(print-conf 'controller-id     "CAN ID:          ")

IMU tilt detection

Read the IMU roll angle and print a warning when the board tilts beyond a threshold.

(define tilt-threshold 0.35)  ; ~20 degrees in radians

(loopwhile t
  (progn
    (define rpy (get-imu-rpy))
    (define roll  (ix rpy 0))
    (define pitch (ix rpy 1))

    (if (> (abs roll) tilt-threshold)
      (print (str-from-n (* roll 57.3) "Warning: roll %.1f deg")))

    (if (> (abs pitch) tilt-threshold)
      (print (str-from-n (* pitch 57.3) "Warning: pitch %.1f deg")))

    (sleep 0.1)))

CAN bus communication

Sending a raw CAN frame

; Send a standard 11-bit CAN frame to ID 0x100
(can-send-sid 0x100 (list 0x01 0x02 0x03 0x04))

Reading motor state from another VESC over CAN

Use can-cmd to execute a LispBM expression on a remote VESC and return the result:

(define remote-id 2)  ; CAN ID of the other VESC

(loopwhile t
  (progn
    (define remote-rpm (can-cmd remote-id '(get-rpm)))
    (define remote-vin (can-cmd remote-id '(get-vin)))

    (print (str-from-n remote-rpm "Remote RPM: %.0f"))
    (print (str-from-n remote-vin "Remote Vin: %.2f V"))

    (sleep 0.5)))

Listing CAN devices

; Print all VESC devices visible on the CAN bus
(print (can-list-devs))

Receiving CAN frames with events

Enable events to receive CAN frames asynchronously without polling:

(event-enable 'event-can-sid)

(loopwhile t
  (progn
    (define evt (recv 0.5))  ; wait up to 0.5 s for an event
    (if (eq (type-of evt) type-list)
      (match evt
        ((event-can-sid id data)
         (print (str-merge "CAN SID: " (str-from-n id "0x%X")
                           " data: " (to-str data)))))))

Motor fault monitoring

Check for faults and print them to the console:

(defun check-faults ()
  (define fault (get-fault))
  (if (not (eq fault 'fault-none))
    (print (str-merge "FAULT: " (to-str fault)))))

(loopwhile t
  (progn
    (check-faults)
    (sleep 0.1)))

EEPROM: persisting a value across reboots

Store a trip counter in EEPROM so it survives power cycles:

; Read trip counter from EEPROM slot 0 (default 0.0 if unset)
(define trip-m (eeprom-read-f 0))
(print (str-from-n trip-m "Trip: %.1f m"))

; Accumulate distance every 100 ms and save every 10 seconds
(define last-save (systime))

(loopwhile t
  (progn
    (setvar 'trip-m (+ trip-m (* (get-speed) 0.1)))

    (if (> (secs-since last-save) 10.0)
      (progn
        (eeprom-store-f 0 trip-m)
        (setvar 'last-save (systime))
        (print (str-from-n trip-m "Saved trip: %.1f m"))))

    (sleep 0.1)))

Spawning a background monitoring thread

Run motor control in the main thread and monitor temperature in a background thread:

; Background thread: monitor temperatures
(spawn (lambda ()
  (loopwhile t
    (progn
      (define fet-temp (get-temp-fet))
      (define mot-temp (get-temp-mot))

      (if (> fet-temp 80.0)
        (print (str-from-n fet-temp "High FET temp: %.1f C")))

      (if (> mot-temp 100.0)
        (print (str-from-n mot-temp "High motor temp: %.1f C")))

      (sleep 1.0)))))

; Main thread: motor control
(loopwhile t
  (progn
    (set-duty 0.2)
    (timeout-reset)
    (sleep 0.01)))