From b737fe70a6c3fc811845d0e43097a4d4a5abf88c Mon Sep 17 00:00:00 2001
From: mrtoy-me <118446898+mrtoy-me@users.noreply.github.com>
Date: Tue, 23 Apr 2024 09:16:55 +1000
Subject: [PATCH] Fix SHT3xd fails sometimes in 2024.4.0 (#6592)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
---
 esphome/components/sht3xd/sht3xd.cpp | 34 +++++++++++++++++++++++-----
 esphome/components/sht3xd/sht3xd.h   |  7 ++++++
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/esphome/components/sht3xd/sht3xd.cpp b/esphome/components/sht3xd/sht3xd.cpp
index 888e954c6b..ffaf5db322 100644
--- a/esphome/components/sht3xd/sht3xd.cpp
+++ b/esphome/components/sht3xd/sht3xd.cpp
@@ -6,9 +6,14 @@ namespace sht3xd {
 
 static const char *const TAG = "sht3xd";
 
-// use read serial number register with clock stretching disabled as per other SHT3XD_COMMAND registers
-// which provides support for SHT85 sensor
-// SHT85 does not support clock stretching and uses same registers as SHT3xd with clock stretching disabled
+// https://sensirion.com/media/documents/E5762713/63D103C2/Sensirion_electronic_identification_code_SHT3x.pdf
+// indicates two possible read serial number registers either with clock stretching enabled or disabled.
+// Other SHT3XD_COMMAND registers use the clock stretching disabled register.
+// To ensure compatibility, reading serial number using the register with clock stretching register enabled
+// (used originally in this component) is tried first and if that fails the alternate register address
+// with clock stretching disabled is read.
+
+static const uint16_t SHT3XD_COMMAND_READ_SERIAL_NUMBER_CLOCK_STRETCHING = 0x3780;
 static const uint16_t SHT3XD_COMMAND_READ_SERIAL_NUMBER = 0x3682;
 
 static const uint16_t SHT3XD_COMMAND_READ_STATUS = 0xF32D;
@@ -22,13 +27,19 @@ static const uint16_t SHT3XD_COMMAND_FETCH_DATA = 0xE000;
 void SHT3XDComponent::setup() {
   ESP_LOGCONFIG(TAG, "Setting up SHT3xD...");
   uint16_t raw_serial_number[2];
-  if (!this->get_register(SHT3XD_COMMAND_READ_SERIAL_NUMBER, raw_serial_number, 2)) {
-    this->mark_failed();
-    return;
+  if (!this->get_register(SHT3XD_COMMAND_READ_SERIAL_NUMBER_CLOCK_STRETCHING, raw_serial_number, 2)) {
+    this->error_code_ = READ_SERIAL_STRETCHED_FAILED;
+    if (!this->get_register(SHT3XD_COMMAND_READ_SERIAL_NUMBER, raw_serial_number, 2)) {
+      this->error_code_ = READ_SERIAL_FAILED;
+      this->mark_failed();
+      return;
+    }
   }
+
   this->serial_number_ = (uint32_t(raw_serial_number[0]) << 16) | uint32_t(raw_serial_number[1]);
 
   if (!this->write_command(heater_enabled_ ? SHT3XD_COMMAND_HEATER_ENABLE : SHT3XD_COMMAND_HEATER_DISABLE)) {
+    this->error_code_ = WRITE_HEATER_MODE_FAILED;
     this->mark_failed();
     return;
   }
@@ -36,10 +47,21 @@ void SHT3XDComponent::setup() {
 
 void SHT3XDComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "SHT3xD:");
+  switch (this->error_code_) {
+    case READ_SERIAL_FAILED:
+      ESP_LOGD(TAG, "  Error reading serial number");
+      break;
+    case WRITE_HEATER_MODE_FAILED:
+      ESP_LOGD(TAG, "  Error writing heater mode");
+      break;
+    default:
+      break;
+  }
   if (this->is_failed()) {
     ESP_LOGE(TAG, "  Communication with SHT3xD failed!");
     return;
   }
+  ESP_LOGD(TAG, "  Setup successful");
   ESP_LOGD(TAG, "  Serial Number: 0x%08" PRIX32, this->serial_number_);
   ESP_LOGD(TAG, "  Heater Enabled: %s", this->heater_enabled_ ? "true" : "false");
 
diff --git a/esphome/components/sht3xd/sht3xd.h b/esphome/components/sht3xd/sht3xd.h
index d1a3360e69..74f155121b 100644
--- a/esphome/components/sht3xd/sht3xd.h
+++ b/esphome/components/sht3xd/sht3xd.h
@@ -22,6 +22,13 @@ class SHT3XDComponent : public PollingComponent, public sensirion_common::Sensir
   void set_heater_enabled(bool heater_enabled) { heater_enabled_ = heater_enabled; }
 
  protected:
+  enum ErrorCode {
+    NONE = 0,
+    READ_SERIAL_STRETCHED_FAILED,
+    READ_SERIAL_FAILED,
+    WRITE_HEATER_MODE_FAILED,
+  } error_code_{NONE};
+
   sensor::Sensor *temperature_sensor_{nullptr};
   sensor::Sensor *humidity_sensor_{nullptr};
   bool heater_enabled_{true};