add support for EZO sensor circuits (#1239)

Co-authored-by: Samuel Sieb <samuel@sieb.net>

esphome/components/ezo/ezo.cpp

@@ -0,0 +1,86 @@
+#include "ezo.h"
+#include "esphome/core/log.h"
+
+namespace esphome {
+namespace ezo {
+
+static const char *TAG = "ezo.sensor";
+
+static const uint16_t EZO_STATE_WAIT = 1;
+static const uint16_t EZO_STATE_SEND_TEMP = 2;
+static const uint16_t EZO_STATE_WAIT_TEMP = 4;
+
+void EZOSensor::dump_config() {
+  LOG_SENSOR("", "EZO", this);
+  LOG_I2C_DEVICE(this);
+  if (this->is_failed())
+    ESP_LOGE(TAG, "Communication with EZO circuit failed!");
+  LOG_UPDATE_INTERVAL(this);
+}
+
+void EZOSensor::update() {
+  if (this->state_ & EZO_STATE_WAIT) {
+    ESP_LOGE(TAG, "update overrun, still waiting for previous response");
+    return;
+  }
+  uint8_t c = 'R';
+  this->write_bytes_raw(&c, 1);
+  this->state_ |= EZO_STATE_WAIT;
+  this->start_time_ = millis();
+  this->wait_time_ = 900;
+}
+
+void EZOSensor::loop() {
+  uint8_t buf[20];
+  if (!(this->state_ & EZO_STATE_WAIT)) {
+    if (this->state_ & EZO_STATE_SEND_TEMP) {
+      int len = sprintf((char *) buf, "T,%0.3f", this->tempcomp_);
+      this->write_bytes_raw(buf, len);
+      this->state_ = EZO_STATE_WAIT | EZO_STATE_WAIT_TEMP;
+      this->start_time_ = millis();
+      this->wait_time_ = 300;
+    }
+    return;
+  }
+  if (millis() - this->start_time_ < this->wait_time_)
+    return;
+  buf[0] = 0;
+  if (!this->read_bytes_raw(buf, 20)) {
+    ESP_LOGE(TAG, "read error");
+    this->state_ = 0;
+    return;
+  }
+  switch (buf[0]) {
+    case 1:
+      break;
+    case 2:
+      ESP_LOGE(TAG, "device returned a syntax error");
+      break;
+    case 254:
+      return;  // keep waiting
+    case 255:
+      ESP_LOGE(TAG, "device returned no data");
+      break;
+    default:
+      ESP_LOGE(TAG, "device returned an unknown response: %d", buf[0]);
+      break;
+  }
+  if (this->state_ & EZO_STATE_WAIT_TEMP) {
+    this->state_ = 0;
+    return;
+  }
+  this->state_ &= ~EZO_STATE_WAIT;
+  if (buf[0] != 1)
+    return;
+
+  float val = strtof((char *) &buf[1], nullptr);
+  this->publish_state(val);
+}
+
+void EZOSensor::set_tempcomp_value(float temp) {
+  this->tempcomp_ = temp;
+  this->state_ |= EZO_STATE_SEND_TEMP;
+}
+
+}  // namespace ezo
+}  // namespace esphome

esphome/components/ezo/ezo.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/sensor/sensor.h"
+#include "esphome/components/i2c/i2c.h"
+
+namespace esphome {
+namespace ezo {
+
+/// This class implements support for the EZO circuits in i2c mode
+class EZOSensor : public sensor::Sensor, public PollingComponent, public i2c::I2CDevice {
+ public:
+  void loop() override;
+  void dump_config() override;
+  void update() override;
+  float get_setup_priority() const override { return setup_priority::DATA; };
+
+  void set_tempcomp_value(float temp);
+
+ protected:
+  unsigned long start_time_ = 0;
+  unsigned long wait_time_ = 0;
+  uint16_t state_ = 0;
+  float tempcomp_;
+};
+
+}  // namespace ezo
+}  // namespace esphome

esphome/components/ezo/sensor.py

@@ -0,0 +1,21 @@
+import esphome.codegen as cg
+import esphome.config_validation as cv
+from esphome.components import i2c, sensor
+from esphome.const import CONF_ID
+
+DEPENDENCIES = ['i2c']
+
+ezo_ns = cg.esphome_ns.namespace('ezo')
+
+EZOSensor = ezo_ns.class_('EZOSensor', sensor.Sensor, cg.PollingComponent, i2c.I2CDevice)
+
+CONFIG_SCHEMA = sensor.SENSOR_SCHEMA.extend({
+    cv.GenerateID(): cv.declare_id(EZOSensor),
+}).extend(cv.polling_component_schema('60s')).extend(i2c.i2c_device_schema(None))
+
+
+def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID])
+    yield cg.register_component(var, config)
+    yield sensor.register_sensor(var, config)
+    yield i2c.register_i2c_device(var, config)

tests/test1.yaml

@@ -784,6 +784,10 @@ sensor:
   - platform: mcp9808
     name: "MCP9808 Temperature"
     update_interval: 15s
+  - platform: ezo
+    id: ph_ezo
+    address: 99
+    unit_of_measurement: "pH"
 
 esp32_touch:
   setup_mode: False

tests/test3.yaml

@@ -421,6 +421,10 @@ sensor:
       name: "CSE7766 Current"
     power:
       name: "CSE776 Power"
+  - platform: ezo
+    id: ph_ezo
+    address: 99
+    unit_of_measurement: "pH"
 
 time:
 - platform: homeassistant