Berry add H-bridge example

tasmota/berry/modules/h-bridge.be

@@ -0,0 +1,28 @@
+#
+# H_bridge class in Berry to pilot a H-bridge device
+#
+
+class H_bridge
+  var gpio1, gpio2
+  var max
+
+  # init(phy_gpio1, phy_gpio2) - intialize H-bridge with the 2 GPIOs used to control it
+  def init(gpio1, gpio2)
+    self.gpio1 = gpio1
+    self.gpio2 = gpio2
+    self.max = 1023     # max value of duty
+  end
+
+  # set the value of both PWM values
+  def set(v1, v2)
+    if v1 < 0   v1 = 0 end
+    if v2 < 0   v2 = 0 end
+    if v1 + v2 > self.max
+      raise "value_error", "the sum of duties must not exceed 100%"
+    end
+
+    import gpio
+    gpio.set_pwm(self.gpio1, v1, 0)
+    gpio.set_pwm(self.gpio2, v2, v1)    # dephase by value v1
+  end
+end