feat(example): add nrf52840 demo(no wireless yet)

Signed-off-by: Haobo Gu <[email protected]>

.vscode/settings.json

@@ -11,6 +11,7 @@
         "rmk/Cargo.toml",
         "boards/stm32h7/Cargo.toml",
         "boards/stm32f4/Cargo.toml",
+        "boards/nrf52840/Cargo.toml",
         "boards/rp2040/Cargo.toml"
     ],
     "rust-analyzer.showUnlinkedFileNotification": false,

boards/nrf52840/.cargo/config.toml

@@ -0,0 +1,40 @@
+[target.thumbv7m-none-eabi]
+# uncomment this to make `cargo run` execute programs on QEMU
+# runner = "qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -semihosting-config enable=on,target=native -kernel"
+
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+# uncomment ONE of these three option to make `cargo run` start a GDB session
+# which option to pick depends on your system
+runner = "probe-rs run --chip nRF52840_xxAA"
+# runner = "gdb-multiarch -q -x openocd.gdb"
+# runner = "gdb -q -x openocd.gdb"
+
+rustflags = [
+  # Previously, the linker arguments --nmagic and -Tlink.x were set here.
+  # They are now set by build.rs instead. The linker argument can still
+  # only be set here, if a custom linker is needed.
+
+  # By default, the LLD linker is used, which is shipped with the Rust
+  # toolchain. If you run into problems with LLD, you can switch to the
+  # GNU linker by uncommenting this line:
+  # "-C", "linker=arm-none-eabi-ld",
+
+  # If you need to link to pre-compiled C libraries provided by a C toolchain
+  # use GCC as the linker by uncommenting the three lines below:
+  # "-C", "linker=arm-none-eabi-gcc",
+  # "-C", "link-arg=-Wl,-Tlink.x",
+  # "-C", "link-arg=-nostartfiles",
+]
+
+[build]
+# Pick ONE of these default compilation targets
+# target = "thumbv6m-none-eabi"        # Cortex-M0 and Cortex-M0+
+# target = "thumbv7m-none-eabi"        # Cortex-M3
+target = "thumbv7em-none-eabi"       # Cortex-M4 and Cortex-M7 (no FPU)
+# target = "thumbv7em-none-eabihf"     # Cortex-M4F and Cortex-M7F (with FPU)
+# target = "thumbv8m.base-none-eabi"   # Cortex-M23
+# target = "thumbv8m.main-none-eabi"   # Cortex-M33 (no FPU)
+# target = "thumbv8m.main-none-eabihf" # Cortex-M33 (with FPU)
+
+[env]
+DEFMT_LOG = "error"