In this section, we'll set up the integration in VS Code and run the first program.
✅ Open the nrf52-code/usb-app folder in VS Code and open the src/bin/hello.rs file.
Note: To ensure full rust-analyzer support, do not open the whole
rust-exercisesfolder.
Give rust-analyzer some time to analyze the file and its dependency graph. When it's done, a "Run" button will appear over the main function. If it doesn't appear on its own, type something in the file, delete and save. This should trigger a re-load.
✅ Click the "Run" button to run the application on the microcontroller.
If you are not using VS code run the cargo run --bin hello command from the nrf52-code/usb-app folder.
NOTE: Recent version of the nRF52840-DK have flash-read-out protection to stop people dumping the contents of flash on an nRF52 they received pre-programmed, so if you have problems immediately after first plugging your board in, see this page.
If you run into an error along the lines of "Debug power request failed" retry the operation and the error should disappear.
The usb-app package has been configured to cross-compile applications to the ARM Cortex-M architecture and then run them using the probe-rs custom Cargo runner. The probe-rs tool will load and run the embedded application on the microcontroller and collect logs from the microcontroller.
The probe-rs process will terminate when the microcontroller enters the "halted" state. From the embedded application, one can enter the "halted" state using by performing a CPU breakpoint with a special argument that indicates 'success'. For convenience, an exit function is provided in the dk Board Support Package (BSP). This function is divergent like std::process::exit (fn() -> !) and can be used to halt the device and terminate the probe-rs process.