From 9a2ca63d8c7e1f51d0a28dc90fe40bb7eba5f211 Mon Sep 17 00:00:00 2001
From: Skymaker <lukas@skymaker.info>
Date: Fri, 8 Jan 2021 19:07:28 +0100
Subject: [PATCH] added setHeaterLevel function

---
 src/HTU21D.cpp | 27 +++++++++++++++++++++++++++
 src/HTU21D.h   |  1 +
 2 files changed, 28 insertions(+)

diff --git a/src/HTU21D.cpp b/src/HTU21D.cpp
index 6dcbe12..87a8e79 100644
--- a/src/HTU21D.cpp
+++ b/src/HTU21D.cpp
@@ -186,6 +186,33 @@ void HTU21D::setHeater(HTU21D_HEATER_SWITCH heaterSwitch)
   write8(HTU21D_USER_REGISTER_WRITE, userRegisterData);
 }
 
+/**************************************************************************/
+/*
+    setHeaterLevel()
+
+    Set the Heater level (between 3.09 mA and 94.20 mA, see datasheet)
+
+    NOTE:
+    - prolonged exposure to high humidity will result gradual upward drift
+      of the RH reading, the heater is used to drive off condensation &
+      reverse drift effect.
+    - heater consumtion is 3.09mA - 94.20mA @ 3.3v.
+*/
+/**************************************************************************/
+void HTU21D::setHeaterLevel(byte heaterLevel)
+{
+  uint8_t heaterRegisterData = 0;
+
+  heaterRegisterData = read8(HTU21D_HEATER_REGISTER_READ);
+  
+  heaterLevel &= 0x0F;
+  heaterRegisterData &= 0xF0;
+  heaterRegisterData |= heaterLevel;
+  
+  write8(HTU21D_HEATER_REGISTER_WRITE, heaterRegisterData);
+}
+
+
 /**************************************************************************/
 /*
     readHumidity()
diff --git a/src/HTU21D.h b/src/HTU21D.h
index 9c5df82..4e0e7d9 100644
--- a/src/HTU21D.h
+++ b/src/HTU21D.h
@@ -133,6 +133,7 @@ class HTU21D
    void     softReset(void);
    bool     batteryStatus(void);
    void     setHeater(HTU21D_HEATER_SWITCH heaterSwitch);
+   void     setHeaterLevel(byte heaterLevel);
    uint16_t readDeviceID(void);
    uint8_t  readFirmwareVersion(void);