Driver for JSN-SR04T waterproof ultrasonic sensor

HARDWARE.md

@@ -128,7 +128,7 @@ Polling and reading follow a call and response pattern.
 | 7 Segment Display  | :yellow_heart:     | Digital Out       | `LED::SevenSegment`   | No decimal point
 | 8x8 LED (MAX7219)  | :heart:            | SPI               | `LED::MAX7219`        |
 | TM1637             | :heart:            | BitBang SPI       | `LED::TM1637`         | 4x 7 Segment + Colon
-| Neopixel / WS2812B | :yellow_heart:     | Adafruit Library  | `LED::WS2812`         | Not working on RP2040
+| Neopixel / WS2812B | :green_heart:      | Adafruit Library  | `LED::WS2812`         |
 | Dotstar / APA102   | :green_heart:      | SPI               | `LED::APA102`         |
 
 ### Displays
@@ -226,6 +226,7 @@ Polling and reading follow a call and response pattern.
 | :--------------- | :------:       | :--------    | :---------------   |------ |
 | HC-SR04          | :green_heart:  | Digi In/Out  | `Sensor::HCSR04`   | Ultrasonic, 20-4000mm
 | RCWL-9620        | :green_heart:  | I2C          | `Sensor::RCWL9260` | Ultrasonic, 20-4500mm
+| JSN-SR04T        | :green_heart:  | UART         | `Sensor::JSNSR04T` | Mode 2 ONLY. Use HC-SR04 driver for mode 0 or 4.
 | VL53L0X          | :heart:        | I2C          | `Sensor::VL53L0X`  | Laser, 30 - 1000mm
 | GP2Y0E03         | :heart:        | I2C          | `Sensor::GP2Y0E03` | Infrared, 40 - 500mm
 

examples/sensor/jsnsr04t.rb

@@ -0,0 +1,15 @@
+#
+# Example of reading a JSN-SR04T ultrasonic sensor, in mode 2.
+#
+require 'bundler/setup'
+require 'denko'
+
+board = Denko::Board.new(Denko::Connection::Serial.new)
+uart = Denko::UART::Hardware.new(board: board, index: 1, baud: 9600)
+ultrasonic = Denko::Sensor::JSNSR04T.new(board: board, uart: uart)
+
+ultrasonic.poll(1) do |distance|
+  puts "Distance: #{distance} mm"
+end
+
+sleep

lib/denko/sensor.rb

@@ -14,6 +14,7 @@ module Sensor
     autoload :QMP6988,     "#{__dir__}/sensor/qmp6988"
     autoload :RCWL9620,    "#{__dir__}/sensor/rcwl9620"
     autoload :HCSR04,      "#{__dir__}/sensor/hcsr04"
+    autoload :JSNSR04T,    "#{__dir__}/sensor/jsnsr04t"
     autoload :GenericPIR,  "#{__dir__}/sensor/generic_pir"
   end
 end

lib/denko/sensor/jsnsr04t.rb

@@ -0,0 +1,53 @@
+module Denko
+  module Sensor
+    #
+    # For JSN-SR04T sensor in mode 2 ONLY.
+    #
+    class JSNSR04T
+      include Behaviors::Component
+      include Behaviors::Lifecycle
+      include Behaviors::Poller
+
+      UART_CLASSES = [Denko::UART::Hardware, Denko::UART::BitBang]
+      TIMEOUT      = 0.500
+      MATCHER      = /(\d*)mm/
+
+      attr_reader :uart
+
+      after_initialize do
+        unless (params[:uart] && UART_CLASSES.include?(params[:uart].class))
+          raise ArgumentError, "JSN-SR04T driver only works in mode 2, and expects a UART in the :uart key"
+        end
+
+        raise StandardError, "UART baud must be 9600 for JSN-SR04T" unless params[:uart].baud == 9600
+
+        @uart = params[:uart]
+      end
+
+      def _read
+        # Trigger read
+        uart.write("U")
+        sleep 0.100
+
+        # Get line from UART
+        start = Time.now
+        line  = nil
+        until line || (Time.now - start > TIMEOUT)
+          line = uart.gets
+          sleep 0.010
+        end
+
+        # Extract mm as integer
+        if line && match = line.match(MATCHER)
+          value = match[1].to_i
+          if value
+            self.update(value)
+            return value
+          end
+        else
+          return nil
+        end
+      end
+    end
+  end
+end