Add support for DFRobot HCHO Formaldehyde Sensor (SEN0231)

CODEOWNERS

@@ -280,6 +280,7 @@ esphome/components/sdm_meter/* @jesserockz @polyfaces
 esphome/components/sdp3x/* @Azimath
 esphome/components/selec_meter/* @sourabhjaiswal
 esphome/components/select/* @esphome/core
+esphome/components/sen0231/* @cwitting
 esphome/components/sen0321/* @notjj
 esphome/components/sen21231/* @shreyaskarnik
 esphome/components/sen5x/* @martgras

esphome/components/sen0231/__init__.py

@@ -0,0 +1 @@
+CODEOWNERS = ["@cwitting"]

esphome/components/sen0231/sen0231.cpp

@@ -0,0 +1,66 @@
+#include "sen0231.h"
+#include "esphome/core/log.h"
+#include "esphome/core/hal.h"
+
+namespace esphome {
+namespace sen0231_sensor {
+
+static const char *const TAG = "sen0231_sensor.sensor";
+
+static constexpr uint8_t START_BYTE = 0;
+static constexpr uint8_t NAME_BYTE = 1;
+static constexpr uint8_t UNIT_BYTE = 2;
+static constexpr uint8_t NUM_DECIMAL_BYTE = 3;
+static constexpr uint8_t CONCENTRATION_HIGH_BYTE = 4;
+static constexpr uint8_t CONCENTRATION_LOW_BYTE = 5;
+static constexpr uint8_t FULL_RANGE_HIGH_BYTE = 6;
+static constexpr uint8_t FULL_RANGE_LOW_BYTE = 7;
+static constexpr uint8_t CHECKSUM_BYTE = 8;
+static constexpr uint8_t NUM_BYTES = 9;
+
+void Sen0231Sensor::setup() { ESP_LOGCONFIG(TAG, "Setting up sen0231..."); }
+
+void Sen0231Sensor::update() { this->read_data_(); }
+
+void Sen0231Sensor::dump_config() {
+  ESP_LOGCONFIG(TAG, "DF Robot Formaldehyde Sensor sen0231:");
+  LOG_UPDATE_INTERVAL(this);
+}
+
+uint8_t check_sum(const uint8_t array[], uint8_t length) {
+  uint8_t sum = 0;
+  for (int i = 1; i < length - 1; i++) {
+    sum += array[i];
+  }
+  sum = (~sum) + 1;
+  return sum;
+}
+
+void Sen0231Sensor::read_data_() {
+  uint8_t buffer[NUM_BYTES] = {0};
+
+  // Read the full buffer, but we are only interested in the last frame
+  while (available() > 0) {
+    for (uint8_t i = 0; i < NUM_BYTES - 1; i++) {
+      // Shift buffer
+      buffer[i] = buffer[i + 1];
+    }
+
+    // Fill into last element
+    buffer[NUM_BYTES - 1] = read();
+  }
+
+  uint8_t check_val = check_sum(buffer, NUM_BYTES);
+  if ((buffer[START_BYTE] != 0xFF) || (buffer[NAME_BYTE] != 0x17) || (buffer[UNIT_BYTE] != 0x04) ||
+      (buffer[CHECKSUM_BYTE] != check_val)) {
+    ESP_LOGE(TAG, "Error in received data %d, %d, %d, %d", buffer[START_BYTE], buffer[NAME_BYTE], buffer[UNIT_BYTE],
+             buffer[CHECKSUM_BYTE]);
+    return;
+  }
+
+  float val = ((uint16_t) (buffer[CONCENTRATION_HIGH_BYTE] << 8) + buffer[CONCENTRATION_LOW_BYTE]) / 1000.0;
+  this->publish_state(val);
+}
+
+}  // namespace sen0231_sensor
+}  // namespace esphome

esphome/components/sen0231/sen0231.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/sensor/sensor.h"
+#include "esphome/components/uart/uart.h"
+
+// ref:
+// https://wiki.dfrobot.com/Gravity__HCHO_Sensor_SKU__SEN0231
+
+namespace esphome {
+namespace sen0231_sensor {
+
+class Sen0231Sensor : public sensor::Sensor, public PollingComponent, public uart::UARTDevice {
+ public:
+  void update() override;
+  void dump_config() override;
+  void setup() override;
+
+ protected:
+  void read_data_();
+};
+
+}  // namespace sen0231_sensor
+}  // namespace esphome

esphome/components/sen0231/sensor.py

@@ -0,0 +1,34 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import uart, sensor
+from esphome.const import (
+    ICON_CHEMICAL_WEAPON,
+    UNIT_PARTS_PER_MILLION,
+    STATE_CLASS_MEASUREMENT,
+)
+
+CODEOWNERS = ["@cwitting"]
+DEPENDENCIES = ["uart"]
+
+sen0231_sensor_ns = cg.esphome_ns.namespace("sen0231_sensor")
+Sen0231Sensor = sen0231_sensor_ns.class_(
+    "Sen0231Sensor", cg.PollingComponent, uart.UARTDevice
+)
+
+CONFIG_SCHEMA = (
+    sensor.sensor_schema(
+        Sen0231Sensor,
+        unit_of_measurement=UNIT_PARTS_PER_MILLION,
+        icon=ICON_CHEMICAL_WEAPON,
+        accuracy_decimals=3,
+        state_class=STATE_CLASS_MEASUREMENT,
+    )
+    .extend(cv.polling_component_schema("60s"))
+    .extend(uart.UART_DEVICE_SCHEMA)
+)
+
+
+async def to_code(config):
+    var = await sensor.new_sensor(config)
+    await cg.register_component(var, config)
+    await uart.register_uart_device(var, config)

tests/test1.yaml

@@ -263,6 +263,11 @@ uart:
     rx_pin: GPIO10
     parity: EVEN
     baud_rate: 9600
+  - id: sen0231_uart
+    rx_pin:
+      allow_other_uses: true
+      number: 27
+    baud_rate: 9600
 
 ota:
   safe_mode: true
@@ -1326,6 +1331,11 @@ sensor:
     id: sen0321_ozone
     update_interval: 10s
     i2c_id: i2c_bus
+  - platform: sen0231
+    name: Workshop Formaldehyde Sensor
+    id: sen0231_formaldehyde
+    update_interval: 10s
+    uart_id: sen0231_uart
   - platform: sgp30
     eco2:
       name: Workshop eCO2