Running the Program from VS Code

Both cargo-embed and cargo-flash are tools based on the probe-rs library. This library exposes an API to communicate with the J-Link and perform all the operations exposed by the JTAG protocol. We have developed a small Cargo runner called probe-run that uses the probe-rs library to streamline the process of running a program and printing logs, like cargo-embed, while also having better integration into VS code. We'll be using it in this workshop, and you can utilize it in your future projects too.

✅ Open the src/bin/hello.rs file and click the "Run" button that's hovering over the main function.

Note: you will get the "Run" button if the Rust analyzer's workspace is set to the beginner/apps folder. This will be the case if the current folder in VS code (left side panel) is set to beginner/apps.

If you are not using VS code, you can run the program out of your console. Enter the command cargo run --bin hello from within the beginer/apps folder. Rust Analyzer's "Run" button is a short-cut for that command.

Expected output:

$ cargo run --bin hello
INFO:hello -- Hello, world!
stack backtrace:
   0: 0x0000229c - __bkpt
   1: 0x0000030e - hello::__cortex_m_rt_main
   2: 0x0000011a - main
   3: 0x00001ba2 - Reset

cargo run will compile the application and then invoke probe-run with its argument set to the path of the output ELF file.

Unlike cargo-embed, probe-run will terminate when the program reaches a breakpoint (asm::bkpt) that halts the device. Before exiting, probe-run will print a stack backtrace of the program starting from the breakpoint. This can be used to write small test programs that are meant to perform some work and then terminate.