SunFounder Thales Kit, Manual

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SunFounder Thales Kit for Raspberry Pi Pico, Release 1.0
4. Connect the yellow lead of the servo to the GP15 pin with a jumper wire.
5. Connect the brawn lead of the servo to the negative power bus with a jumper wire.
Code
When the program is running, we can see the Servo Arm swinging back and forth from 0° to 180°. The program will
always run because of the
while True
loop, we need to press the Stop key to end the program.
import machine
import utime
servo = machine . PWM(machine . Pin( 15 ))
servo . freq( 50 )
def interval_mapping (x, in_min, in_max, out_min, out_max):
return (x - in_min)
*
(out_max - out_min) / (in_max - in_min) + out_min
def servo_write (pin,angle):
pulse_width = interval_mapping(angle, 0 , 180 , 0.5 , 2.5 )
duty = int (interval_mapping(pulse_width, 0 , 20 , 0 , 65535 ))
pin . duty_u16(duty)
while True :
for angle in range ( 180 ):
servo_write(servo,angle)
utime . sleep_ms( 20 )
for angle in range ( 180 , - 1 , - 1 ):
servo_write(servo,angle)
utime . sleep_ms( 20 )
How it works?
We defined the
servo_write()
function to make the servo run.
This function has two parameters:
• pin, the GPIO pin that controls the servo.
• Angle, the angle of the shaft output.
In this function,
interval_mapping()
is called to map the angle range 0 ~ 180 to the pulse width range 0.5 ~
2.5ms.
pulse_width = interval_mapping(angle, 0 , 180 , 0.5 , 2.5 )
Why is it 0.5~2.5? This is determined by the working mode of the Servo.
Servo
Next, convert the pulse width from period to duty. Since duty_u16() cannot have decimals when used (the value cannot
be a float type), we used
int()
to force the duty to be converted to an int type.
duty = int (interval_mapping(pulse_width, 0 , 20 , 0 , 65535 ))
Finally, write the duty value into duty_u16().
3.4. Projects 87