update README

Author: bjsowa

README.md

@@ -6,10 +6,50 @@ The main functionalities include:
 - velocity commands for the robot,
 - velocity and PWM commands for individual wheels,
 - battery voltage feedback,
-- wheel states (position, velocity, PWM duty) feedback,
+- wheel states (position, velocity, torque, PWM duty) feedback,
 - odometry feedback (calculated from wheel encoders),
 - feedback from the IMU sensor.
 
-It uses [rosserial] client library to expose its functionalities on ROS topics, services and parameters.
+The project is written for [PlatformIO] and uses the [STM32Cube] embedded software libraries. The low-level code is generated by the [STM32CubeMX] tool.
 
-[LeoCore]: https://www.leorover.tech/documentation/leo-core
+The firmware also uses [rosserial] client library to expose its functionalities on ROS topics, services and parameters. For the documentation of the ROS API, visit [leo_fw] on the ROS wiki.
+
+## Prerequisites
+To build the project, all you'll need is [Visual Studio Code] with the [PlatformIO IDE] extension.
+
+To change the [STM32CubeMX] configuration, you will also need the [stm32pio] tool in order to properly regenerate the code.
+
+## Building
+Open the project in [PlatformIO IDE], then run the `PlatformIO: Build` task.
+
+## Flashing
+### Using ST-Link programmer
+Connect the ST-Link to the pins on the [LeoCore] debug pin header, then run the `PlatformIO: Upload` task.
+
+You can also run the GDB debugger by running the `PIO Debug` launch configuration (or just clicking `F5`).
+
+### Using RPi on Leo Rover
+Upload the `.pio/build/genericSTM32F401RC/firmware.bin` to Leo Rover, then, on the robot, run:
+```
+rosrun leo_fw flash firmware.bin
+```
+
+## Modifying STM32CubeMX configuration\
+Open the `leocore.ioc` project in [STM32CubeMX], make the changes and save the project.
+
+**Don't** click `GENERATE CODE`. Instead, type:
+```
+stm32pio generate
+```
+The current configuration assumes that [STM32CubeMX] is installed under `/opt/STM32CubeMX`. You can change the path in the `stm32pio.ini` file.
+
+[LeoCore]: https://www.leorover.tech/documentation/leo-core
+[leo_fw]: http://wiki.ros.org/leo_fw
+[Visual Studio Code]: https://code.visualstudio.com
+[rosserial]: http://wiki.ros.org/rosserial
+[stm32pio]: https://github.com/ussserrr/stm32pio
+[PlatformIO IDE]: https://platformio.org/platformio-ide
+[PlatformIO]: https://docs.platformio.org/en/latest/what-is-platformio.html
+[STM32Cube]: https://www.st.com/en/ecosystems/stm32cube.html
+[STM32CubeMX]: https://www.st.com/en/development-tools/stm32cubemx.html
+[Visual Studio Code]: https://code.visualstudio.com