Add Buzzer to Presto module.

modules/py_frozen/presto.py

@@ -5,12 +5,27 @@
 from ezwifi import EzWiFi
 
 from collections import namedtuple
+from machine import Pin, PWM
 from picographics import PicoGraphics, DISPLAY_PRESTO, DISPLAY_PRESTO_FULL_RES
 
 
 Touch = namedtuple("touch", ("x", "y", "touched"))
 
 
+class Buzzer:
+    def __init__(self, pin):
+        self.pwm = PWM(Pin(pin))
+
+    def set_tone(self, freq, duty=0.5):
+        if freq < 50.0:  # uh... https://github.com/micropython/micropython/blob/af64c2ddbd758ab6bac0fcca94c66d89046663be/ports/rp2/machine_pwm.c#L105-L119
+            self.pwm.duty_u16(0)
+            return False
+
+        self.pwm.freq(freq)
+        self.pwm.duty_u16(int(65535 * duty))
+        return True
+
+
 class Presto():
     NUM_LEDS = 7
     LED_PIN = 33