From 4b2d402cc0eb59da07e601dc3c257c76cd88956b Mon Sep 17 00:00:00 2001
From: Pascal Sachs <pascal.sachs@sensirion.com>
Date: Tue, 3 Aug 2021 11:04:07 +0200
Subject: [PATCH 1/2] Fix CRC calculation for TX frames

* Add number of command bytes, since they must not be included
  when deciding if a CRC should be included
* CRC is added every third byte excluding command bytes
---
 src/SensirionI2CTxFrame.cpp | 10 ++++++----
 src/SensirionI2CTxFrame.h   |  4 +++-
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/SensirionI2CTxFrame.cpp b/src/SensirionI2CTxFrame.cpp
index a803ee2..b55242c 100644
--- a/src/SensirionI2CTxFrame.cpp
+++ b/src/SensirionI2CTxFrame.cpp
@@ -37,8 +37,9 @@
 #include "SensirionErrors.h"
 
 SensirionI2CTxFrame::SensirionI2CTxFrame(uint8_t buffer[], size_t bufferSize,
-                                         size_t index)
-    : _buffer(buffer), _bufferSize(bufferSize), _index(index) {
+                                         size_t numCommandBytes)
+    : _buffer(buffer), _bufferSize(bufferSize), _index(numCommandBytes),
+      _numCommandBytes(numCommandBytes) {
 }
 
 SensirionI2CTxFrame::SensirionI2CTxFrame(uint8_t buffer[], size_t bufferSize)
@@ -57,7 +58,8 @@ SensirionI2CTxFrame
 SensirionI2CTxFrame::createWithUInt16Command(uint16_t command, uint8_t buffer[],
                                              size_t bufferSize) {
     SensirionI2CTxFrame instance = SensirionI2CTxFrame(buffer, bufferSize, 2);
-    instance.addCommand(command);
+    instance._buffer[0] = static_cast<uint8_t>((command & 0xFF00) >> 8);
+    instance._buffer[1] = static_cast<uint8_t>((command & 0x00FF) >> 0);
     return instance;
 }
 
@@ -144,7 +146,7 @@ uint16_t SensirionI2CTxFrame::_addByte(uint8_t data) {
         return TxFrameError | BufferSizeError;
     }
     _buffer[_index++] = data;
-    if (_index % 2 == 0) {
+    if ((_index - _numCommandBytes) % 3 == 2) {
         if (_bufferSize <= _index) {
             return TxFrameError | BufferSizeError;
         }
diff --git a/src/SensirionI2CTxFrame.h b/src/SensirionI2CTxFrame.h
index 2343804..27660c5 100644
--- a/src/SensirionI2CTxFrame.h
+++ b/src/SensirionI2CTxFrame.h
@@ -175,7 +175,8 @@ class SensirionI2CTxFrame {
     uint16_t addBytes(const uint8_t data[], size_t dataLength);
 
   private:
-    SensirionI2CTxFrame(uint8_t buffer[], size_t bufferSize, size_t index);
+    SensirionI2CTxFrame(uint8_t buffer[], size_t bufferSize,
+                        size_t numCommandBytes);
 
     static uint8_t _generateCRC(const uint8_t* data, size_t count);
 
@@ -184,6 +185,7 @@ class SensirionI2CTxFrame {
     uint8_t* _buffer;
     size_t _bufferSize;
     size_t _index;
+    size_t _numCommandBytes;
 };
 
 #endif /* SENSIRION_I2C_TX_FRAME_H_ */

From 3b7b3c8fca4841b80f067e0dba54a8247363a80e Mon Sep 17 00:00:00 2001
From: Pascal Sachs <pascal.sachs@sensirion.com>
Date: Tue, 3 Aug 2021 11:11:49 +0200
Subject: [PATCH 2/2] Prepare for 0.5.2 Release

Bugfix release to fix CRC insertion in I2C TX frames
---
 CHANGELOG.rst      | 13 +++++++++++--
 library.properties |  2 +-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 9dec260..6e77e6e 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -6,6 +6,15 @@ All notable changes to this project will be documented in this file.
 The format is based on `Keep a Changelog <https://keepachangelog.com/en/1.0.0/>`_
 and this project adheres to `Semantic Versioning <https://semver.org/spec/v2.0.0.html>`_.
 
+`0.5.2`_ 2021-08-03
+-------------------
+
+Fixed
+.....
+
+- Fix CRC insertion in ``SensirionI2CTxFrame`` when more then one parameter
+  is sent to the sensor.
+
 `0.5.1`_ 2021-07-08
 -------------------
 
@@ -14,7 +23,6 @@ Changed
 
 - Adjusted deprecation warnings
 
-
 `0.5.0`_ 2021-07-07
 -------------------
 
@@ -121,7 +129,8 @@ Removed
 - Initial release
 
 
-.. _Unreleased: https://github.com/Sensirion/arduino-core/compare/0.5.1...main
+.. _Unreleased: https://github.com/Sensirion/arduino-core/compare/0.5.2...main
+.. _0.5.2: https://github.com/Sensirion/arduino-core/compare/0.5.1...0.5.2
 .. _0.5.1: https://github.com/Sensirion/arduino-core/compare/0.5.0...0.5.1
 .. _0.5.0: https://github.com/Sensirion/arduino-core/compare/0.4.3...0.5.0
 .. _0.4.3: https://github.com/Sensirion/arduino-core/compare/0.4.2...0.4.3
diff --git a/library.properties b/library.properties
index 0e2ddb9..ff826f8 100644
--- a/library.properties
+++ b/library.properties
@@ -1,5 +1,5 @@
 name=Sensirion Core
-version=0.5.1
+version=0.5.2
 author=Sensirion
 maintainer=Sensirion
 sentence=Library containing code base for Sensirion Sensor Libraries.