[!NOTE] In colaboration with Anton, a more detailed variant of this info was created here.
I could not find an official vendor web site for the servos, here the best data sheet I could find. There is also a smaller 2x3.5x5 sized Geekservo, but it is less convenient as it has an odd axle position, only turns 270° and has the axle only on one side.
The example below uses the latest version of the Antons servo module. The MicroPython firmware for LMS-ESP32 includes an older version.
Pybricks has an optional wait=True|False parameter for Lego motors, but here the rs.call() always behaves like wait=False, so you have to add an appropriate wait(msec) if you want to wait until the movement is finished. According to the data sheet the servo needs 0.14 seconds per 60° rotation. This matches my observation of roughly ~1 second for full 360°.
from pupremote import PUPRemoteSensor
from servo import Servo
def servo(v):
print(v)
sv.angle(v)
sv = Servo(21, min_pulse = 518, max_pulse = 2510, min_angle=0, max_angle=360)
rs = PUPRemoteSensor(power=True)
rs.add_command('servo', '', 'h')
rs.process()
while True:
rs.process()
If the code above fails with TypeError: unexpected keyword argument 'min_pulse' add a servo.py file with latest content from antonvh:mpy_robot_tools/servo.py.
The pulse values have to be adjusted for each servo individually
from pybricks.pupdevices import ForceSensor
from pybricks.parameters import Port
from pybricks.tools import wait
from pupremote_hub import PUPRemoteHub # copy from https://github.com/antonvh/PUPRemote/blob/main/src/pupremote_hub.py
fs = ForceSensor(Port.A)
rh = PUPRemoteHub(Port.B)
rh.add_command('servo', '', 'h')
while True:
v = min(360, int(fs.force()*36.0)) # map from [0,10.xx] to [0,360]
print(v)
rh.call('servo', v)
wait(100)
To run the servo at lower speed you can use something like this in Pybricks:
for i in range(0,360,b):
rh.call('servo',i)
rh.call('servo',360)
with
| value of b | speed in °/sec |
|---|---|
| 4 | ~360 |
| 3 | ~240 |
| 2 | ~180 |
| 1 | ~90 |
where 4 is basically full speed and the slower the speed, the more irregular the movement.