Implement RCWL-9620 I2C ultrasonic distance sensor

HARDWARE.md

@@ -211,7 +211,7 @@ Polling and reading follow a call and response pattern.
 | Name             | Status         | Interface    | Component Class    | Notes |
 | :--------------- | :------:       | :--------    | :---------------   |------ |
 | HC-SR04          | :heart:        | Digi In/Out  | `Sensor::HCSR04`   | Ultrasonic, 20-4000mm
-| RCWL-9620        | :heart:        | I2C          | `Sensor::RCWL9260` | Ultrasonic, 20-4500mm
+| RCWL-9620        | :green_heart:  | I2C          | `Sensor::RCWL9260` | Ultrasonic, 20-4500mm
 | VL53L0X          | :heart:        | I2C          | `Sensor::VL53L0X`  | Laser, 30 - 1000mm
 | GP2Y0E03         | :heart:        | I2C          | `Sensor::GP2Y0E03` | Infrared, 40 - 500mm
 

examples/sensor/rcwl9620.rb

@@ -0,0 +1,15 @@
+#
+# Example using an RCWL-9620 sensor over I2C to measure distance.
+#
+require 'bundler/setup'
+require 'denko'
+
+board = Denko::Board.new(Denko::Connection::Serial.new)
+bus = Denko::I2C::Bus.new(board: board, pin: :SDA)
+sensor = Denko::Sensor::RCWL9620.new(bus: bus) # address: 0x57 default
+
+sensor.poll(1) do |distance|
+  puts "Distance is #{distance} mm"
+end
+
+sleep

lib/denko/sensor.rb

@@ -13,5 +13,6 @@ module Sensor
     autoload :AHT20,       "#{__dir__}/sensor/aht"
     autoload :SHT3X,       "#{__dir__}/sensor/sht3x"
     autoload :QMP6988,     "#{__dir__}/sensor/qmp6988"
+    autoload :RCWL9620,    "#{__dir__}/sensor/rcwl9620"
   end
 end

lib/denko/sensor/rcwl9620.rb

@@ -0,0 +1,34 @@
+module Denko
+  module Sensor
+    class RCWL9620
+      include I2C::Peripheral
+      include Behaviors::Poller
+
+      def before_initialize(options={})
+        @i2c_address = 0x57
+        super(options)
+      end
+
+      def _read
+        i2c_write(0x01)
+        sleep(0.120)
+        i2c_read(nil, 3)
+      end
+
+      def pre_callback_filter(bytes)
+        # Data is in micrometers, 3 bytes, big-endian.
+        um = (bytes[0] << 16) + (bytes[1] << 8) + bytes[2]
+        mm = um / 1000.0
+
+        # Limit output between 20 and 4500mm.
+        if mm > 4500.0
+          return 4500.0
+        elsif mm < 20.0
+          return 20.0
+        else
+          return mm
+        end
+      end
+    end
+  end
+end