From faf1c8bee8aff24ab331397529a75355f18011e8 Mon Sep 17 00:00:00 2001
From: Keith Burzinski <kbx81x@gmail.com>
Date: Wed, 8 Sep 2021 16:42:35 -0500
Subject: [PATCH] SGP40 sensor start-up fix (#2178)

---
 esphome/components/sgp40/sgp40.cpp | 17 ++++++++++++-----
 esphome/components/sgp40/sgp40.h   |  1 +
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/esphome/components/sgp40/sgp40.cpp b/esphome/components/sgp40/sgp40.cpp
index 8d93b3e1b1..a911c107b9 100644
--- a/esphome/components/sgp40/sgp40.cpp
+++ b/esphome/components/sgp40/sgp40.cpp
@@ -78,27 +78,28 @@ void SGP40Component::setup() {
 }
 
 void SGP40Component::self_test_() {
-  ESP_LOGD(TAG, "selfTest started");
+  ESP_LOGD(TAG, "Self-test started");
   if (!this->write_command_(SGP40_CMD_SELF_TEST)) {
     this->error_code_ = COMMUNICATION_FAILED;
-    ESP_LOGD(TAG, "selfTest communicatin failed");
+    ESP_LOGD(TAG, "Self-test communication failed");
     this->mark_failed();
   }
 
   this->set_timeout(250, [this]() {
     uint16_t reply[1];
     if (!this->read_data_(reply, 1)) {
-      ESP_LOGD(TAG, "selfTest read_data_ failed");
+      ESP_LOGD(TAG, "Self-test read_data_ failed");
       this->mark_failed();
       return;
     }
 
     if (reply[0] == 0xD400) {
-      ESP_LOGD(TAG, "selfTest completed");
+      this->self_test_complete_ = true;
+      ESP_LOGD(TAG, "Self-test completed");
       return;
     }
 
-    ESP_LOGD(TAG, "selfTest failed");
+    ESP_LOGD(TAG, "Self-test failed");
     this->mark_failed();
   });
 }
@@ -154,6 +155,12 @@ int32_t SGP40Component::measure_voc_index_() {
  */
 uint16_t SGP40Component::measure_raw_() {
   float humidity = NAN;
+
+  if (!this->self_test_complete_) {
+    ESP_LOGD(TAG, "Self-test not yet complete");
+    return UINT16_MAX;
+  }
+
   if (this->humidity_sensor_ != nullptr) {
     humidity = this->humidity_sensor_->state;
   }
diff --git a/esphome/components/sgp40/sgp40.h b/esphome/components/sgp40/sgp40.h
index b9ea365169..62936102e7 100644
--- a/esphome/components/sgp40/sgp40.h
+++ b/esphome/components/sgp40/sgp40.h
@@ -68,6 +68,7 @@ class SGP40Component : public PollingComponent, public sensor::Sensor, public i2
   int32_t seconds_since_last_store_;
   SGP40Baselines baselines_storage_;
   VocAlgorithmParams voc_algorithm_params_;
+  bool self_test_complete_;
   bool store_baseline_;
   int32_t state0_;
   int32_t state1_;