bsp-demo: Add defmt

example-code/nrf52/bsp_demo/.cargo/config.toml

@@ -2,7 +2,11 @@
 target = "thumbv7em-none-eabihf"
 
 [target.thumbv7em-none-eabihf]
-runner = "probe-run --chip nRF52840_xxAA"
+runner = "probe-rs run --chip nRF52840_xxAA --allow-erase-all"
 rustflags = [
   "-C", "link-arg=-Tlink.x",
+  "-C", "link-arg=-Tdefmt.x",
 ]
+
+[env]
+DEFMT_LOG = "debug"

example-code/nrf52/bsp_demo/.vscode/launch.json

@@ -1,20 +1,22 @@
 {
-    "version": "0.2.0",
-    "configurations": [
-      {
-        "preLaunchTask": "${defaultBuildTask}",
-        "type": "probe-rs-debug",
-        "request": "launch",
-        "name": "Run bsp_demo",
-        "flashingConfig": {
-          "flashingEnabled": true,
-        },
-        "chip": "nrf52840_xxaa",
-        "coreConfigs": [
-          {
-            "programBinary": "./target/thumbv7em-none-eabihf/debug/bsp_demo"
-          }
-        ]
-      }
-    ]
-  }
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "preLaunchTask": "${defaultBuildTask}",
+      "type": "probe-rs-debug",
+      "request": "launch",
+      "name": "Run bsp_demo",
+      "flashingConfig": {
+        "flashingEnabled": true
+      },
+      "chip": "nrf52840_xxaa",
+      "coreConfigs": [
+        {
+          "coreIndex": 0,
+          "rttEnabled": true,
+          "programBinary": "./target/thumbv7em-none-eabihf/debug/bsp_demo"
+        }
+      ],
+    }
+  ]
+}

example-code/nrf52/bsp_demo/Cargo.toml

@@ -7,5 +7,8 @@ edition = "2021"
 
 [dependencies]
 cortex-m-rt = "0.6"
-cortex-m = "0.6"
+cortex-m = { version = "0.7", features = ["critical-section-single-core"] }
 nrf52840-dk-bsp = { version = "0.2.0", features = [ "rt" ] }
+defmt = "0.3"
+defmt-rtt = "0.4"
+critical-section = "1.2.0"

example-code/nrf52/bsp_demo/src/main.rs

@@ -1,27 +1,50 @@
+//! A simple LED blinking demo for nRF52840-DK
+//!
+//! Demonstrates using a Board Support Package, defmt, and the probe-rs extension for VS Code
+
 #![no_std]
 #![no_main]
 
 use core::fmt::Write;
 use cortex_m_rt::entry;
 use nrf52840_dk_bsp::{hal, Board};
 
+extern crate defmt_rtt;
+
 #[entry]
 fn main() -> ! {
-    let mut nrf52 = Board::take().unwrap();
-    let mut timer = hal::Timer::new(nrf52.TIMER0);
+    // We do some hardware set-up first
+    defmt::info!("Starting up...");
+    let mut board = Board::take().unwrap();
+    let mut timer = hal::Timer::new(board.TIMER0);
+
+    // Now go into an infinite loop
     loop {
-        writeln!(nrf52.cdc, "On!").unwrap();
-        nrf52.leds.led_2.enable();
+        // We're logging over both defmt, and the J-Link's UART to USB Serial
+        // Port interface.
+        defmt::debug!("On!");
+        writeln!(board.cdc, "On!").unwrap();
+
+        // Control the LED
+        board.leds.led_2.enable();
+
+        // Wait for 1 second (this is a 1 MHz timer)
         timer.delay(1_000_000);
-        writeln!(nrf52.cdc, "Off!").unwrap();
-        nrf52.leds.led_2.disable();
+
+        // More logging
+        defmt::debug!("Off!");
+        writeln!(board.cdc, "Off!").unwrap();
+
+        // Control the LED
+        board.leds.led_2.disable();
+
+        // Wait for 1 second again
         timer.delay(1_000_000);
     }
 }
 
 #[panic_handler]
-fn panic(_info: &core::panic::PanicInfo) -> ! {
-    loop {
-        cortex_m::asm::udf();
-    }
+fn panic(info: &core::panic::PanicInfo) -> ! {
+    defmt::error!("Panic! {:?}", defmt::Debug2Format(&info));
+    cortex_m::asm::udf();
 }