Adding DFRobot Ozone Sensor Support (sen0321) (#4782)

esphome/components/sen0321/sen0321.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/sensor/sensor.h"
+#include "esphome/components/i2c/i2c.h"
+
+// ref:
+// https://github.com/DFRobot/DFRobot_OzoneSensor
+
+namespace esphome {
+namespace sen0321_sensor {
+// Sensor Mode
+// While passive is supposedly supported, it does not appear to work reliably.
+static const uint8_t SENSOR_MODE_REGISTER = 0x03;
+static const uint8_t SENSOR_MODE_AUTO = 0x00;
+static const uint8_t SENSOR_MODE_PASSIVE = 0x01;
+static const uint8_t SET_REGISTER = 0x04;
+
+// Each register is 2 wide, so 0x07-0x08 for passive, or 0x09-0x0A for auto
+// First register is high bits, next low.
+static const uint8_t SENSOR_PASS_READ_REG = 0x07;
+static const uint8_t SENSOR_AUTO_READ_REG = 0x09;
+
+class Sen0321Sensor : public sensor::Sensor, public PollingComponent, public i2c::I2CDevice {
+ public:
+  void update() override;
+  void dump_config() override;
+  void setup() override;
+
+ protected:
+  void read_data_();
+};
+
+}  // namespace sen0321_sensor
+}  // namespace esphome