Add script to build for generating VCS ID.

Author: dhebbeker

README.md

@@ -39,6 +39,12 @@ Alternatively the software may be executed in a simulation environment.
 This project uses [PlatformIO](https://platformio.org/) as build system and package manager.
 PlatformIO may be used via a GUI (PlatformIO IDE) or command line interface (PlatformIO Core). The project configuration ([`platformio.ini`](platformio.ini)) is part of this repository.
 
+System requirements:
+
+- [PlatformIO](https://platformio.org/)
+- [Python](https://www.python.org/) interpreter
+- optional: [git](https://git-scm.com/) client is used to generate version identifier if project files are in a git clone
+
 In order to use the software (some call it "firmware"), the following steps are required:
 
 1. Build (the default configuration of) the project.

generate_vcs_identifier.py

@@ -0,0 +1,18 @@
+"""Adds a CPP definition of a version identifier using version control system.
+
+This script shall be loaded by PlatformIO when building the project.
+It is not designed to be run independently.
+"""
+
+import subprocess
+Import("env")
+
+def get_vcs_id():    
+    vcs_output = subprocess.run(["git", "describe", "--always", "--dirty", "--all"], stdout=subprocess.PIPE, text=True)
+    vcs_string = vcs_output.stdout.strip()
+    print ("vcs string: " + vcs_string)
+    return (vcs_string)
+
+env.Append(CPPDEFINES=[
+  ("VCS_ID", env.StringifyMacro(get_vcs_id())),
+])

platformio.ini

@@ -21,6 +21,8 @@ build_flags =
 	-DLV_CONF_PATH="${PROJECT_DIR}/lib/3rd_party_adapters/LVGL/lv_conf.h" ; lvgl: use this config file
 	-DBAUD_RATE=${this.monitor_speed}
 monitor_speed = 115200
+extra_scripts =
+	pre:generate_vcs_identifier.py
 
 [env:native]
 platform = native