Using BSEC 2 library for bme688 with Thingy53

Question

I'm developing a custom project for thingy53. 
 I'm trying to use the bsec2 library to use the bme688 in Thingy53, but there's no reference example anywhere. 
 With the library provided by bosch, the libalgobsec.a and bsec_interface.h and bsec_datatypes.h files, I succeed to compile together. 
 But I don't know how to program them including config files. 
 I find the example with bme680 which is integrated in Thingy91, the asset tracker. 
 However, that was meaningless because the bsec library version is different (bme680 -> bsec v1.4x / bme688 -> bsec v2.0x) and because of different version, the structure of library is also different. 
 
 I think the Thingy53's edge-impulse example uses bme688. But also, unlike Thiny52, Thingy53's source code is not distributed. 
 
 So, is there example that adopts bme688's bsec lib. v2.0x for the custom project? 
 If not, How could I integrate bsec v2.0x library to my custom project?

Here's my CMakeList.txt. I built my project based on Nordic_LBS example from NCS v2.0.0 (zephyr) with Thingy53. 
 #
# Copyright (c) 2018 Nordic Semiconductor
#
# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
#
cmake_minimum_required(VERSION 3.20.0)

set(PM_STATIC_YML_FILE
 ${CMAKE_CURRENT_SOURCE_DIR}/boards/pm_static_${BOARD}.yml
 )

find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
project(THINGY53_AMG88XX_BLE_APP)

# NORDIC SDK APP START
target_sources(app PRIVATE src/main.c)

# Preinitialization related to Thingy:53 DFU
target_sources_ifdef(CONFIG_BOARD_THINGY53_NRF5340_CPUAPP app PRIVATE
 boards/thingy53.c
)
target_sources_ifdef(CONFIG_BOARD_THINGY53_NRF5340_CPUAPP_NS app PRIVATE
 boards/thingy53.c
)

# NORDIC SDK APP END
zephyr_library_include_directories(.)
zephyr_library_include_directories({ZEPHYR_BASE}/drivers/sensor/amg88xx)

# zephyr_library_sources(amg88xx.c)
# zephyr_library_sources_ifdef(CONFIG_AMG88XX_TRIGGER amg88xx_trigger.c)

#External library config
# The external static library that we are linking with does not know
# how to build for this platform so we export all the flags used in
# this zephyr build to the external build system.
#
# Other external build systems may be self-contained enough that they
# do not need any build information from zephyr. Or they may be
# incompatible with certain zephyr options and need them to be
# filtered out.
zephyr_get_include_directories_for_lang_as_string( C includes)
zephyr_get_system_include_directories_for_lang_as_string(C system_includes)
zephyr_get_compile_definitions_for_lang_as_string( C definitions)
zephyr_get_compile_options_for_lang_as_string( C options)

set(external_project_cflags
 "${includes} ${definitions} ${options} ${system_includes}"
 )

include(ExternalProject)

# Add an external project to be able download and build the third
# party library. In this case downloading is not necessary as it has
# been committed to the repository.
set(lib_gt2_src_dir ${CMAKE_CURRENT_SOURCE_DIR}/lib_gt2)
set(lib_gt2_build_dir ${CMAKE_CURRENT_BINARY_DIR}/lib_gt2)

set(LIB_GT2_LIB_DIR ${lib_gt2_build_dir}/lib)
set(LIB_GT2_SOURCE_DIR ${lib_gt2_build_dir}/src)
set(LIB_GT2_INCLUDE_DIR ${lib_gt2_src_dir}/include)

if(CMAKE_GENERATOR STREQUAL "Unix Makefiles")
# https://www.gnu.org/software/make/manual/html_node/MAKE-Variable.html
set(submake "$(MAKE)")
else() # Obviously no MAKEFLAGS. Let's hope a "make" can be found somewhere.
set(submake "make")
endif()

ExternalProject_Add(
 lib_gt2_grideye_project # Name for custom target
 PREFIX ${lib_gt2_build_dir} # Root dir for entire project
 SOURCE_DIR ${lib_gt2_src_dir}
 BINARY_DIR ${lib_gt2_src_dir} # This particular build system is invoked from the root
 CONFIGURE_COMMAND "" # Skip configuring the project, e.g. with autoconf
 BUILD_COMMAND
 ${submake}
 PREFIX=${lib_gt2_build_dir}
 CC=${CMAKE_C_COMPILER}
 AR=${CMAKE_AR}
 CFLAGS=${external_project_cflags}
 INSTALL_COMMAND "" # This particular build system has no install command
 BUILD_BYPRODUCTS ${LIB_GT2_LIB_DIR}/lib_gt2.a
 BUILD_BYPRODUCTS ${LIB_GT2_SOURCE_DIR}/libalgobsec.a
 DEPENDS zephyr_interface
 )

# Create a wrapper CMake library that our app can link with
add_library(lib_gt2_grideye STATIC IMPORTED GLOBAL)
add_dependencies(
 lib_gt2_grideye
 lib_gt2_grideye_project
 )
set_target_properties(lib_gt2_grideye PROPERTIES IMPORTED_LOCATION ${LIB_GT2_LIB_DIR}/lib_gt2.a)
# set_target_properties(lib_gt2_grideye PROPERTIES IMPORTED_LOCATION ${LIB_GT2_SOURCE_DIR}/libalgobsec.a)
set_target_properties(lib_gt2_grideye PROPERTIES INTERFACE_INCLUDE_DIRECTORIES ${LIB_GT2_INCLUDE_DIR})

# BSEC static library configuration
add_library(lib_bsec STATIC IMPORTED GLOBAL)
# add_dependencies(lib_bsec)
set_target_properties(lib_bsec PROPERTIES IMPORTED_LOCATION ${LIB_GT2_SOURCE_DIR}/libalgobsec.a)
set_target_properties(lib_bsec PROPERTIES INTERFACE_INCLUDE_DIRECTORIES ${LIB_GT2_INCLUDE_DIR})

target_link_libraries(app PUBLIC lib_gt2_grideye)

wass · Answer

Hi, I would like to bring an update to this thread which I believe can help the community with a ready reference example. I would like first to thank rtlab_hmkang which answer helped me with the .a lib integration in Zephyr, hereby I would like to share a full project source code with driver, library integrations in Zephyr and multiple testing samples and complete application. The answer is similar to the one I posted here which is a similar question, this one focus on Bsec2 which is also included in the project Gas resistance values from BME688 on Thingy:53 here the project link https://github.com/HomeSmartMesh/sdk-hsm-thingy53 
 some details 
 
 BME688 Zephyr Driver : in hsm/drivers/sensor/bme688 
 
 BME68x-Sensor-API vendor driver integration https://github.com/boschsensortec/BME68x-Sensor-API 
 Using Zephyr's Sensor API in C language for usage in BME688 simple forced mode 
 Driver extension functions to use BME688 in Parallel mode and get all x10 gas measures

BME688 Server : in hsm/subsys/bme688_server 
 
 C++ wrapper to configure the BME688 usage in json structure (temperatures profile and durations) 
 handler delivers the sensor results in a json structure (temperature, humidity, pressure, gas-0..gas-9) 
 Bosch-BSEC2-Library .a vendor's binary integration for IAQ (Indoor Air Quality) measurements https://github.com/boschsensortec/Bosch-BSEC2-Library

Mesh Network with OpenThread broadcasting UDP packets as client and running a sensors server. 
 C++ application with json inputs for config and outputs for sensors enables direct mapping to MQTT 
 RGB Led, Light color, Battery 
 
 if only interested in BSec2 integration then it's possible to check the sample 08_bme688_bsec2 Here an overview about the driver and library integration, more details on the project readme.

rtlab_hmkang · Answer

Hi Hieu, 
 Finally, I found what I missed, and I want you to know how I solved the problem. 
 
 My very first "CMakeLists.txt" includes ExternalProjectAdd() cmake command. 
 This cmake command can add external static library with *.c and *.h files coded by the user. But, this command needs to know the *.c and *.h file's directory which includes Makefile of the source and header file. Here is the Makefile of its directory. 
 PREFIX ?= .
OBJ_DIR ?= $(PREFIX)/obj
LIB_DIR ?= $(PREFIX)/lib

all:
	mkdir -p $(OBJ_DIR) $(LIB_DIR)
	$(CC) -c $(CFLAGS) -MD -Iinclude src/gt2_grideye.c -o $(OBJ_DIR)/gt2_grideye.o
	# $(CC) -c $(CFLAGS) -MD -Iinclude src/gt2_environment.c -o $(OBJ_DIR)/gt2_environment.o ./include/libalgobsec.a 
	$(CC) $(CFLAGS) -MD -Iinclude src/gt2_environment.c -o $(OBJ_DIR)/gt2_environment.o 
	$(CC) -c $(CFLAGS) -MD -Iinclude src/gt2_ble_service.c -o $(OBJ_DIR)/gt2_ble_service.o
	$(AR) -rcs $(LIB_DIR)/lib_gt2.a $(OBJ_DIR)/*.o
	
clean:
	rm -rf $(OBJ_DIR) $(LIB_DIR) 
 This Makefile makes a static library named "lib_gt2.a". I succeed to link "lib_gt2.a" to my main project and it worked properly. The "gt2_environment.c" uses bsec library, I need to let the gt2_environment.c know where the static library is. However, when I tried to link "libalgobsec.a" with this makefile, by adding "./include/libalgobsec.a -lm" to end of the "~~gt2_environment.o" line, Makefile and the gcc complier only said that they can't find bsec libraries. 
 Like this, the Makefile does not find zephyr and nrf-sdk specific headers. Because the zephyr based project is managed by "cmake", specific directories' specific makefile isn't good to link external library. 
 So, I restructured my project's code tree, and I finally could compile the project. 
 Here is my new CMakeLists.txt and my new directory structure. #
# Copyright (c) 2018 Nordic Semiconductor
#
# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
#
cmake_minimum_required(VERSION 3.20.0)