Closes #11

README.md

@@ -924,7 +924,30 @@ It can be integrated with:
 - qmake
 - Makefile
 
-Just add the source files to the project.
+Open `dbc.pro` in Qt Creator to see two subprojects: `core` and `tests`.
+`core/core.pro` builds the C++17 static library `dbc_core` without a Qt dependency.
+`tests/tests.pro` builds the QtTest executable `dbc_tests` and links that library.
+The root project declares `tests.depends = core` for parallel builds.
+
+Build out of source (Qt 6; use `qmake` for Qt 5):
+
+```sh
+mkdir build
+cd build
+qmake6 ../dbc.pro
+make -j
+make check
+```
+
+`core/core_files.pri` lists the library sources and headers.
+Consumers include `core/core.pri` for include paths and library linkage; the test
+source lists live in `tests/parser_tests.pri` and `tests/decoder_tests.pri`.
+When building a consumer separately, pass
+`DBC_CORE_BUILD_DIR=/absolute/path/to/build/core` to qmake.
+
+The former demonstration program is preserved in `examples/main.cpp` with
+`examples/demo.pro`. Build it separately after building core, using that same
+`DBC_CORE_BUILD_DIR` option; run `dbc_demo <file.dbc>`.
 
 ---
 
@@ -962,7 +985,7 @@ This gives FrameTap a much better foundation for real use, because both browsing
 
 ## Regression tests
 
-See [tests/README.md](tests/README.md) for compiler and qmake commands.
+See [tests/README.md](tests/README.md) for QtTest build and execution commands.
 Tests cover frame validation and error locations, Intel and Motorola extraction,
 signed and unsigned 64-bit boundaries,
 physical conversion, numeric output, and invalid signal payloads.