From c6109024aaff83c9a44ccd579f5994fafe4a3078 Mon Sep 17 00:00:00 2001
From: James Braid <251628+jamesbraid@users.noreply.github.com>
Date: Mon, 13 Sep 2021 02:23:59 -0700
Subject: [PATCH] Fix SM300D2 sensor component routines so they correctly read
 the sensor output (#2159)

---
 esphome/components/sm300d2/sensor.py   | 4 ++--
 esphome/components/sm300d2/sm300d2.cpp | 8 +++++---
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/esphome/components/sm300d2/sensor.py b/esphome/components/sm300d2/sensor.py
index 8452ee81f2..0c3c54f200 100644
--- a/esphome/components/sm300d2/sensor.py
+++ b/esphome/components/sm300d2/sensor.py
@@ -72,13 +72,13 @@ CONFIG_SCHEMA = cv.All(
             ),
             cv.Optional(CONF_TEMPERATURE): sensor.sensor_schema(
                 unit_of_measurement=UNIT_CELSIUS,
-                accuracy_decimals=0,
+                accuracy_decimals=1,
                 device_class=DEVICE_CLASS_TEMPERATURE,
                 state_class=STATE_CLASS_MEASUREMENT,
             ),
             cv.Optional(CONF_HUMIDITY): sensor.sensor_schema(
                 unit_of_measurement=UNIT_PERCENT,
-                accuracy_decimals=0,
+                accuracy_decimals=1,
                 device_class=DEVICE_CLASS_HUMIDITY,
                 state_class=STATE_CLASS_MEASUREMENT,
             ),
diff --git a/esphome/components/sm300d2/sm300d2.cpp b/esphome/components/sm300d2/sm300d2.cpp
index b1787581ae..d542582fcb 100644
--- a/esphome/components/sm300d2/sm300d2.cpp
+++ b/esphome/components/sm300d2/sm300d2.cpp
@@ -9,10 +9,12 @@ static const uint8_t SM300D2_RESPONSE_LENGTH = 17;
 
 void SM300D2Sensor::update() {
   uint8_t response[SM300D2_RESPONSE_LENGTH];
+  uint8_t peeked;
+
+  while (this->available() > 0 && this->peek_byte(&peeked) && peeked != 0x3C)
+    this->read();
 
-  flush();
   bool read_success = read_array(response, SM300D2_RESPONSE_LENGTH);
-  flush();
 
   if (!read_success) {
     ESP_LOGW(TAG, "Reading data from SM300D2 failed!");
@@ -63,7 +65,7 @@ void SM300D2Sensor::update() {
   if (this->pm_2_5_sensor_ != nullptr)
     this->pm_2_5_sensor_->publish_state(pm_2_5);
 
-  ESP_LOGD(TAG, "Received pm_10_0: %u µg/m³", pm_10_0);
+  ESP_LOGD(TAG, "Received PM10: %u µg/m³", pm_10_0);
   if (this->pm_10_0_sensor_ != nullptr)
     this->pm_10_0_sensor_->publish_state(pm_10_0);