add pwm demo and backlight setting demo

examples/peripheral/pwm/pwm_servo.py

@@ -0,0 +1,26 @@
+from maix import pwm, time, pinmap
+
+SERVO_PERIOD = 50     # 50Hz 20ms
+SERVO_MIN_DUTY = 2.5  # 2.5% -> 0.5ms
+SERVO_MAX_DUTY = 12.5  # 12.5% -> 2.5ms
+
+# Use PWM7
+pwm_id = 7
+# !! set pinmap to use PWM7
+pinmap.set_pin_function("A19", "PWM7")
+
+
+
+def angle_to_duty(percent):
+    return (SERVO_MAX_DUTY - SERVO_MIN_DUTY) * percent / 100.0 + SERVO_MIN_DUTY
+
+
+out = pwm.PWM(pwm_id, freq=SERVO_PERIOD, duty=angle_to_duty(0), enable=True)
+
+for i in range(100):
+    out.duty(angle_to_duty(i))
+    time.sleep_ms(100)
+
+for i in range(100):
+    out.duty(angle_to_duty(100 - i))
+    time.sleep_ms(100)

examples/vision/display/display_backlight.py

@@ -0,0 +1,19 @@
+from maix import pwm, time, display, image
+
+disp = display.Display()
+
+def show(i):
+    img = image.Image(disp.width(), disp.height())
+    img.draw_circle(disp.width() // 2, disp.height() //2, 50, image.COLOR_RED, thickness=-1)
+    img.draw_string(2, 2, f"{i}%", image.COLOR_WHITE, scale=2)
+    disp.show(img)
+
+for i in range(100):
+    disp.set_backlight(i)
+    show(i)
+    time.sleep_ms(50)
+
+for i in range(100):
+    disp.set_backlight(100 - i)
+    show(100 - i)
+    time.sleep_ms(50)

maix/version.py

@@ -3,6 +3,6 @@
 
 version_major = 4
 version_minor = 1
-version_patch = 0
+version_patch = 2
 
 __version__ = "{}.{}.{}".format(version_major, version_minor, version_patch)