Add more info about the project.

.github/workflows/build.yml

@@ -30,7 +30,7 @@ jobs:
       - name: Build default project using build.py
         run: python build.py
       - name: Upload hex file
-        uses: actions/upload-artifact@v1
+        uses: actions/upload-artifact@v4
         with:
-          name: build-py-${{ matrix.os }}
+          name: MICROBIT.hex
           path: MICROBIT.hex

README.md

@@ -1,12 +1,39 @@
-# BBC micro:bit V2 Battery Voltage Project
+# BBC micro:bit V2 Battery Voltage Measurement
 
 A C++ example project showing how to measure the BBC micro:bit V2 battery
 voltage.
 
+This project measures the input voltage, in millivolts, from the nRF52833
+microcontroller and prints it on the display and serial.
+
+A prebuilt hex file can be download from the
+[GitHub Releases page](https://github.com/microbit-foundation/microbit-v2-battery-voltage/releases).
+
+A similar example for micro:bit V1 can be found in:
+https://os.mbed.com/teams/microbit/code/microbit-battery-test/
+
+## How is the battery voltage measured
+
+To measure the micro:bit battery voltage, the nRF52833 (the target MCU)
+microcontroller ADC is used to measure its Vdd input voltage.
+
 All the ADC channels are currently used for the Analogue pins and the on-board
-microphone, so for this project we hijack the ADC channel used for P0 and
+microphone, so for this example we hijack the ADC channel used for P0 and
 re-route it to the internal Vdd (voltage from the microcontroller power input).
 
+It's important to note that there are two protection diodes and a voltage
+regulator between the battery connector and the microcontroller Vdd pin,
+as can be seen in the
+[micro:bit open source schematics](https://github.com/microbit-foundation/microbit-v2-hardware).
+
+So, there is a voltage drop on these components that will vary on different
+factors, like the current load and component temperature.
+Through some of the micro:bit testing we measured this voltage
+drop ranging from 210 to 300 mV (measured without any additional
+load on the micro:bit power supply).
+However, these values should not be considered definitive,
+as they may further fluctuate under different conditions.
+
 ## Building the project
 
 ### Dependencies
@@ -15,8 +42,9 @@ re-route it to the internal Vdd (voltage from the microcontroller power input).
 - [Git](https://git-scm.com)
 - [CMake](https://cmake.org/download/)
 - [Python 3](https://www.python.org/downloads/)
+- [Ninja Build](https://ninja-build.org/) (only needed on Windows)
 
-For example, on Ubuntu:
+For example, to install these dependencies on Ubuntu:
 
 ```
 sudo apt install gcc