Add support for SMT100 Soil Moisture Sensor (#3654)

Co-authored-by: Dennis Piecha <d.piecha@ymail.com>

esphome/components/smt100/smt100.cpp

@@ -0,0 +1,84 @@
+#include "smt100.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace smt100 {
+
+static const char *const TAG = "smt100";
+
+void SMT100Component::update() {
+  ESP_LOGV(TAG, "Sending measurement request");
+  this->write_str("GetAllMeasurements!\r");
+}
+
+void SMT100Component::loop() {
+  static char buffer[MAX_LINE_LENGTH];
+  while (this->available() != 0) {
+    if (readline_(read(), buffer, MAX_LINE_LENGTH) > 0) {
+      int counts = (int) strtol((strtok(buffer, ",")), nullptr, 10);
+      float dielectric_constant = (float) strtod((strtok(nullptr, ",")), nullptr);
+      float moisture = (float) strtod((strtok(nullptr, ",")), nullptr);
+      float temperature = (float) strtod((strtok(nullptr, ",")), nullptr);
+      float voltage = (float) strtod((strtok(nullptr, ",")), nullptr);
+
+      if (this->counts_sensor_ != nullptr) {
+        counts_sensor_->publish_state(counts);
+      }
+
+      if (this->dielectric_constant_sensor_ != nullptr) {
+        dielectric_constant_sensor_->publish_state(dielectric_constant);
+      }
+
+      if (this->moisture_sensor_ != nullptr) {
+        moisture_sensor_->publish_state(moisture);
+      }
+
+      if (this->temperature_sensor_ != nullptr) {
+        temperature_sensor_->publish_state(temperature);
+      }
+
+      if (this->voltage_sensor_ != nullptr) {
+        voltage_sensor_->publish_state(voltage);
+      }
+    }
+  }
+}
+
+float SMT100Component::get_setup_priority() const { return setup_priority::DATA; }
+
+void SMT100Component::dump_config() {
+  ESP_LOGCONFIG(TAG, "SMT100:");
+
+  LOG_SENSOR(TAG, "Counts", this->temperature_sensor_);
+  LOG_SENSOR(TAG, "Dielectric Constant", this->temperature_sensor_);
+  LOG_SENSOR(TAG, "Temperature", this->temperature_sensor_);
+  LOG_SENSOR(TAG, "Moisture", this->moisture_sensor_);
+  LOG_UPDATE_INTERVAL(this);
+  this->check_uart_settings(9600);
+}
+
+int SMT100Component::readline_(int readch, char *buffer, int len) {
+  static int pos = 0;
+  int rpos;
+
+  if (readch > 0) {
+    switch (readch) {
+      case '\n':  // Ignore new-lines
+        break;
+      case '\r':  // Return on CR
+        rpos = pos;
+        pos = 0;  // Reset position index ready for next time
+        return rpos;
+      default:
+        if (pos < len - 1) {
+          buffer[pos++] = readch;
+          buffer[pos] = 0;
+        }
+    }
+  }
+  // No end of line has been found, so return -1.
+  return -1;
+}
+
+}  // namespace smt100
+}  // namespace esphome