From c416d74d8c65f423b4e6625a8243448bb23f5826 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20Men=C5=A1=C3=ADk?= <pemensik@fedoraproject.org>
Date: Fri, 24 Apr 2026 23:05:00 +0200
Subject: [PATCH] Add support for Grove sensor SHT31

New support for yet another sensor for measuring temperature and
humidity. That is another part sold by SeedStudio and provides similar
readings to SHT4X.
---
 platformio.ini                                |  2 ++
 .../sensors/EnvironmentSensorManager.cpp      | 27 +++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/platformio.ini b/platformio.ini
index f3ada13386..751e466171 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -127,6 +127,7 @@ build_flags =
   -D ENV_INCLUDE_BME280=1
   -D ENV_INCLUDE_BMP280=1
   -D ENV_INCLUDE_SHTC3=1
+  -D ENV_INCLUDE_SHT31=1
   -D ENV_INCLUDE_SHT4X=1
   -D ENV_INCLUDE_LPS22HB=1
   -D ENV_INCLUDE_INA3221=1
@@ -146,6 +147,7 @@ lib_deps =
   adafruit/Adafruit BME280 Library @ ^2.3.0
   adafruit/Adafruit BMP280 Library @ ^2.6.8
   adafruit/Adafruit SHTC3 Library @ ^1.0.1
+  adafruit/Adafruit SHT31 Library @ ^2.2.2
   sensirion/Sensirion I2C SHT4x @ ^1.1.2
   arduino-libraries/Arduino_LPS22HB @ ^1.0.2
   adafruit/Adafruit MLX90614 Library @ ^2.1.5
diff --git a/src/helpers/sensors/EnvironmentSensorManager.cpp b/src/helpers/sensors/EnvironmentSensorManager.cpp
index e2f0d33e72..93420bd547 100644
--- a/src/helpers/sensors/EnvironmentSensorManager.cpp
+++ b/src/helpers/sensors/EnvironmentSensorManager.cpp
@@ -83,6 +83,14 @@ static Adafruit_BMP280 BMP280(TELEM_WIRE);
 static Adafruit_SHTC3 SHTC3;
 #endif
 
+#if ENV_INCLUDE_SHT31
+#ifndef TELEM_SHT31_ADDRESS
+#define TELEM_SHT31_ADDRESS    0x44      // SHT31 environmental sensor I2C address
+#endif
+#include <Adafruit_SHT31.h>
+static Adafruit_SHT31 SHT31;
+#endif
+
 #if ENV_INCLUDE_SHT4X
 #ifndef TELEM_SHT4X_ADDRESS
 #define TELEM_SHT4X_ADDRESS 0x44
@@ -331,6 +339,21 @@ static void query_sht4x(uint8_t ch, uint8_t, CayenneLPP& lpp) {
 }
 #endif
 
+#if ENV_INCLUDE_SHT31
+static uint8_t init_sht3x(TwoWire* wire, uint8_t addr) {
+  return SHT31.begin(addr) ? 1 : 0;
+}
+
+static void query_sht3x(uint8_t ch, uint8_t, CayenneLPP& lpp) {
+  float temp, humidity;
+
+  if (SHT31.readBoth(&temp, &humidity)) {
+    lpp.addTemperature(ch, temp);
+    lpp.addRelativeHumidity(ch, humidity);
+  }
+}
+#endif
+
 #if ENV_INCLUDE_LPS22HB
 static uint8_t init_lps22hb(TwoWire*, uint8_t) {
   // LPS22HBClass is constructed with the wire reference; begin() uses it.
@@ -570,9 +593,13 @@ static const SensorDef SENSOR_TABLE[] = {
 #if ENV_INCLUDE_SHTC3
   { 0x70,                  "SHTC3",        init_shtc3,    query_shtc3    },
 #endif
+
 #if ENV_INCLUDE_SHT4X
   { TELEM_SHT4X_ADDRESS,   "SHT4X",        init_sht4x,    query_sht4x    },
 #endif
+#if ENV_INCLUDE_SHT31
+  { TELEM_SHT31_ADDRESS,   "SHT3X",        init_sht3x,    query_sht3x    },
+#endif
 #if ENV_INCLUDE_LPS22HB
   { 0x5C,                  "LPS22HB",      init_lps22hb,  query_lps22hb  },
 #endif