Bare-metal Rust Development with PICSimLab

Board details

https://stm32-base.org/boards/STM32F103C8T6-Blue-Pill.html

• Microcontroller: STM32F103C8
• Flash: 64 KB
• RAM: 20 KB
• Clock Speed: 72 MHz
• User LED(s): PC13 (blue; lights when PC13 is LOW)

STM32F103C8

https://www.st.com/en/microcontrollers-microprocessors/stm32f103c8.html

The STM32F103xx medium-density performance line family incorporates the high-performance ARM®Cortex®-M3 32-bit RISC core operating at a 72 MHz frequency, high-speed embedded memories, and an extensive range of enhanced I/Os and peripherals connected to two APB buses. All devices offer two 12-bit ADCs, three general purpose 16-bit timers plus one PWM timer, as well as standard and advanced communication interfaces: up to two I2Cs and SPIs, three USARTs, an USB and a CAN.

Install dependencies

Rust Installation

https://rustup.rs/

curl https://sh.rustup.rs -sSf | sh

Enable Cortex-M3 Development

rustup target add thumbv7m-none-eabi

Note: What is Thumb? See here?

Install the Supporting Tools

cargo install cargo-binutils
rustup component add llvm-tools-preview

sudo apt install \
  gdb-multiarch \
  binutils-arm-none-eabi

Download the project

git clone https://github.com/Doulos/Embedded-Rust-with-PicSimLab.git

Moving to the Project's directory

cd Embedded-Rust-with-PicSimLab

Build

Build the provided project (inside the project's root directory):

cargo build --release                                                             
arm-none-eabi-objcopy -O binary target/thumbv7m-none-eabi/release/bluepill app.bin

You can achieve the same thing by running the shell script:

./run_me.sh

Installing GDB's gdb-dashboard

• Optionally you can install gdb-dashboard for an improved debugging experience by placing the .gdbinit file in your home directory.

wget -P ~ https://github.com/cyrus-and/gdb-dashboard/raw/master/.gdbinit

Note:Depending on your OS setup, GDB might not be able to pick up the .gdbinit directly from your home directory. In this case, you can try to copy the .gdbinit file to the project's directory instead. If this still doesn't not get picked up automatically, You will have to provide it explicitly as you are calling GDB's command line (see later for an example).

• Optionally, If you want a little bit more eye candy with syntax highlighting inside GDB, you can install:

pip install pygments

Getting PicSimLab

PicSimLab is an open-source virtual development boards environment allowing you to execute programs on various popular dev-boards without the need of a Physical board.

• Install PicSimLab (currently using the unstable version : 0.9.2_240706).

https://github.com/lcgamboa/picsimlab/releases/tag/latestbuild

Various executable options are provided in the release web-page, you will need to download and execute the relevant one.

When invoked for the first time, the default board displayed is an Arduino Uno board. For this exercise however, we will use the Cortex-M3 based Blue Pill board.

• Inside the PICSimLab window choose the Blue Pill board by selecting the Board->Blue Pill sub menu
• Set the Qemu CPU MIPS option to Auto.

• Click on the Config Qemu button and select the Wait for GDB option:

• Configure PICSimLab by selecting the sub-menu: File->Configure and capture the following values:

• Enable debug by clicking on the Debug button and make sure that the GDB debug port shows: 1234

• Inside the PICSimLab window, display the peripherals used in this demo by selecting the sub-menu Modules->Spare Parts

• In the Spare Parts window, load the provided periph_configuration.pcf file by selecting the sub-menu File ->Load configuration

• Inside the PicSimLab window, load the binary file app.bin created in an early step with the sub-menu: File->Load Bin

• Inside a terminal window, navigate to the project's directory and call the GDB debugger with the command:

gdb-multiarch target/thumbv7m-none-eabi/release/bluepill

Alternatively, If you are having difficulties getting the .gdbinit file to get detected by GDB, you can use the command:

gdb-multiarch target/thumbv7m-none-eabi/release/bluepill -x .gdbinit

• Connect GDB to the QEMU (blue pill) GDB server with the command:

  target extended-remote localhost:1234

  And you are rolling! You can issue the following commands to get you started with the GDB debug session:

break main
continue
step
next
run

To exit a running application you can type: Ctrl+c .

To reset the embedded program's execution, you can type system_reset

A helpful GDB tutorial can be found here:

https://freecoder.dev/gdb-cheat-sheet/

A helpful cheat-sheet can be found here:

https://freecoder.dev/GDB_Cheat_Sheet.pdf

Links

• Rust embedded book
• Blue pill
• PicSimLab
• STM32F103C8 info and datasheets
• stm32f1xx-hal crate
• awesome-embedded-rust

Troubleshooting

• PICSimLab has crashed and now, it keeps-on exiting immediately whenever I call it.

PICSimLab is configured to load automatically the last configuration used, each time you invoke it. To go back to a clean initial setup, simply remove the directory .picsimlab located inside your home directory.