This page has moved into the new guide: MBC Servo6 6-Port Servo Expander › SPIKE › Pybricks

Pybricks Environment (Servo6)

Warning
You are reading the Pybricks guide, for SPIKE Prime hubs running Pybricks firmware v4.0 or later. Using the official SPIKE App instead? Switch to the official app guide.

Download the library and example

Pybricks library + example (.zip) → put MBC_servo6_Lib.py in your Pybricks project next to the main program, then import it.

🔑 What happens on the first run

When Pybricks opens a UARTDevice, the hub no longer treats the expander as a sensor that needs power, so the library opens the port with UARTDevice(port, 115200, power_pin=1) to ask the hub for battery power. The first time the console shows:

Custom electronics may damage your LEGO hub ... Press Y to proceed.

Press Y once (the hub remembers it). If you press N the servos get no power.

Sync style (one line after another)

from pybricks.tools import wait
from MBC_servo6_Lib import MBC_SERVO6

sv = MBC_SERVO6(1, False)      # expander on Port A (1=A ... 6=F), False = sync mode

sv.servo_angle(1, 90)          # CN1 to 90° (first command moves immediately)
wait(1000)
sv.servo_angle(1, 0, 10)       # to 0° at 60 °/s (10×6)
sv.servo_wait(1)               # wait until it arrives
sv.servo_angle(1, 180, 10)
while sv.is_moving(1):
    print("CN1 mA:", sv.get_current(1), " total mA:", sv.get_total_current())
    wait(100)

sv.servo_run(2, 50)            # CN2 is a 360° servo: half speed forward
wait(2000)
sv.servo_run(2, -50)           # half speed reverse
wait(2000)
sv.servo_run(2, 0)             # stop

print("CN1 stalled:", sv.is_stalled(1), " eFuse fault:", sv.is_power_fault())
sv.stop_all()                  # release all servos before the program ends

Async style (multitask)

from pybricks.tools import wait, run_task
from MBC_servo6_Lib import MBC_SERVO6, run_task   # the library's run_task releases the servos when the program ends

sv = MBC_SERVO6(1, True)       # True = multitask, every call needs await

async def gripper():
    await sv.servo_angle(1, 30, 20)
    await sv.servo_wait(1)
    await sv.servo_angle(1, 120, 20)

async def main():
    await gripper()

run_task(main())

Functions

Function	What it does
`MBC_SERVO6(port, multitask)`	Create the object; `port` 1-6 = Port.A-F; with `multitask` True add `await` to every call
`servo_angle(ch, angle, speed=100)`	Move to angle; `speed` 1-99 = `speed×6` °/s, 100 = immediate
`servo_wait(ch, timeout_ms=10000)`	Wait until it arrives
`servo_run(ch, speed)`	360° servo: -100 to 100, 0 stops
`servo_speed_config(ch, stop_us=1500, span_us=1000)`	Stop pulse and full-speed offset for 360° servos
`servo_pulse(ch, pulse_us)`	Raw pulse width 500-2500 µs
`servo_release(ch)` / `stop_all()`	Release one / all
`servo_calibrate(ch, min_us=500, max_us=2500, range_deg=180)`	Pulse and angle range
`servo_stall_config(ch, current_ma=400, time_ms=300, auto_release=True)`	Stall threshold (0 = off)
`get_current(ch)` / `get_total_current()`	Current in mA
`is_moving(ch)` / `is_stalled(ch)` / `is_active(ch)` / `is_power_fault()`	Status

Tip
The expander has no watchdog: servos hold their last position after the program ends. Call stop_all() at the end to release them (the library's run_task does it for you in async style). After an automatic stall release, sending the same angle again does nothing (duplicate commands are ignored); send a different angle or servo_release() first.