深入理解 hello world 例程——基于 cortex-m-quickstart

Rust嵌入式 04-26 13:58 132 閱讀 3 贊 4 收藏 0 評論

在本篇中，將帶你手把手新建一個基于Py32F030的學習板的 hello world 工程。

工具鏈準備

如果您還沒有安裝 Rust 的基本開發環境，您可參考快速搭建環境。

首先，你需要了解你手上的單片機的處理器內核，如 STM32F103 為 Arm® Cortex®-M3 CPU，NRF52840 為 Arm® Cortex®-M4F CPU，CH32V307 為 RISC-V4F 內核。因此你需要根據你芯片內核的來安裝相應的交叉編譯鏈。常見的嵌入式交叉編譯工具如下。

?  rust-embedded-start git:(main) ? rustup target list | grep none
aarch64-unknown-none
aarch64-unknown-none-softfloat
armebv7r-none-eabi
armebv7r-none-eabihf
armv7a-none-eabi
armv7r-none-eabi
armv7r-none-eabihf
loongarch64-unknown-none
loongarch64-unknown-none-softfloat
riscv32i-unknown-none-elf
riscv32im-unknown-none-elf
riscv32imac-unknown-none-elf
riscv32imafc-unknown-none-elf
riscv32imc-unknown-none-elf
riscv64gc-unknown-none-elf
riscv64imac-unknown-none-elf
thumbv6m-none-eabi (installed)
thumbv7em-none-eabi
thumbv7em-none-eabihf
thumbv7m-none-eabi (installed)
thumbv8m.base-none-eabi
thumbv8m.main-none-eabi
thumbv8m.main-none-eabihf
x86_64-unknown-none

Rust 交叉工具鏈的目標是由三元組組成，也叫目標三元組。

它通常采用 --- 的形式來描述目標平臺的架構、供應商、操作系統和應用程序二進制接口（ABI）。

架構（arch）

例如，thumbv7m - none - eabi中的thumbv7m表示 ARM 架構下的 Thumb - 2 指令集的 v7m 版本。這告訴編譯器生成的代碼要符合這種特定的 ARM 架構指令集要求，不同的 ARM 指令集（如 ARMv8、Thumb - 2 等）有不同的性能和功能特點，編譯器需要根據這個信息生成合適的機器碼。
對于powerpc - unknown - linux - gnu中的powerpc，它代表 PowerPC 架構，這是一種與 ARM 不同的處理器架構，具有自己的指令集和硬件特性，編譯器要按照 PowerPC 的規則來生成代碼。

供應商（vendor）

在目標三元組中，供應商部分可以提供關于硬件制造商的信息。不過在很多情況下，none這樣的標識被使用，表示這不是特定某個供應商的硬件定義，或者是通用的定義。例如，在thumbv7m - none - eabi中，none表示這個定義不是針對某一個特定的 ARM 芯片供應商（如三星、恩智浦等），而是一種通用的 ARM Thumb - 2 v7m 指令集的定義。

操作系統（sys）

操作系統部分明確了目標代碼運行的操作系統環境。例如，linux表示目標代碼是運行在 Linux 操作系統之上。這會影響編譯器如何處理系統調用、庫鏈接等操作。對于嵌入式系統，可能會看到none（表示沒有操作系統，如裸機環境），像thumbv7m - none - eabi中的none就表明這個代碼可能是用于沒有操作系統的 ARM 嵌入式設備，編譯器就不會生成與復雜操作系統交互的代碼部分。
而powerpc - unknown - linux - gnu中的linux說明代碼是為運行在 PowerPC 架構的 Linux 系統準備的，編譯器需要確保生成的代碼能夠與 Linux 的系統調用接口、文件系統等兼容。

應用程序二進制接口（ABI）

ABI 部分定義了二進制層面上函數調用、數據結構布局等的規則。例如，eabi（嵌入式應用程序二進制接口）在thumbv7m - none - eabi中是用于嵌入式系統的 ABI 標準。它規定了如何在二進制層面上傳遞參數、返回值等。不同的 ABI 標準適用于不同的應用場景，gnu（如在powerpc - unknown - linux - gnu中）是一種在 Linux 系統上常用的 ABI，遵循 GNU 的規則來處理函數調用和數據結構布局等。

在清楚對應的交叉編譯起三元組名后，你需要使用命令安裝它，如對于 Py32f030 芯片來說，內核是 ARM Cortex-M0+ , 無浮點加速，因此需要安裝 thumbv6m-none-eabi

rustup target add thumbv6m-none-eabi

其他常見內核的單片機與交叉編譯器對應如下：

ARM Cortex-M0: thumbv6m-none-eabi
ARM Cortex-M3： thumbv7m-none-eabi
ARM Cortex-M4: thumbv7em-none-eabi
ARM Cortex-M7: thumbv7em-none-eabi
ARM Cortex-M33: thumbv8m.main-none-eabi
ARM Cortex-M4F: thumbv7em-none-eabihf
ARM Cortex-M7F: thumbv7em-none-eabihf

如果使用錯誤的交叉編譯器編譯 Rust 代碼，可能編譯失敗或生成的固件運行指令會異常。

創建工程

基于模板創建新工程。使用命令：cargo generate --git https://github.com/rust-embedded/cortex-m-quickstart, 然后輸入合適的工程名字即可。

?  tmp cargo generate --git https://github.com/rust-embedded/cortex-m-quickstart --name py32f030_hello_world_start
????   Destination: /Users/hunter/Desktop/tmp/tmp/py32f030_hello_world_start ...
????   project-name: py32f030_hello_world_start ...
????   Generating template ...
????   Moving generated files into: `/Users/hunter/Desktop/tmp/tmp/py32f030_hello_world_start`...
????   Initializing a fresh Git repository
?   Done! New project created /Users/hunter/Desktop/tmp/tmp/py32f030_hello_world_start

修改

創建的工程可能與你的芯片并不完全匹配，因此你可能需要檢查以下幾個部分：

初步編譯，可以正常通過，但此時可能并不能在您的主板上運行正常。

修改

創建的工程可能與你的芯片并不完全匹配，因此你可能需要檢查以下幾個部分：

初步編譯，可以正常通過，但此時可能并不能在您的主板上運行正常。

?  py32f030_hello_world_start git:(master) ? cargo b
    Updating crates.io index
     Locking 31 packages to latest compatible versions
      Adding aligned v0.3.5 (latest: v0.4.2)
      Adding as-slice v0.1.5 (latest: v0.2.1)
      Adding bare-metal v0.2.5 (latest: v1.0.0)
      Adding bitfield v0.13.2 (latest: v0.17.0)
      Adding cortex-m v0.6.7 (latest: v0.7.7)
      Adding cortex-m-rt v0.6.15 (latest: v0.7.5)
      Adding cortex-m-rt-macros v0.6.15 (latest: v0.7.5)
      Adding cortex-m-semihosting v0.3.7 (latest: v0.5.0)
      Adding embedded-hal v0.2.7 (latest: v1.0.0)
      Adding generic-array v0.12.4 (latest: v1.1.0)
      Adding generic-array v0.13.3 (latest: v1.1.0)
      Adding generic-array v0.14.7 (latest: v1.1.0)
      Adding nb v0.1.3 (latest: v1.1.0)
      Adding panic-halt v0.2.0 (latest: v1.0.0)
      Adding r0 v0.2.2 (latest: v1.0.0)
      Adding rustc_version v0.2.3 (latest: v0.4.1)
      Adding semver v0.9.0 (latest: v1.0.23)
      Adding semver-parser v0.7.0 (latest: v0.10.2)
      Adding syn v1.0.109 (latest: v2.0.87)
   Compiling semver-parser v0.7.0
   Compiling typenum v1.17.0
   Compiling cortex-m v0.7.7
   Compiling proc-macro2 v1.0.89
   Compiling version_check v0.9.5
   Compiling unicode-ident v1.0.13
   Compiling nb v1.1.0
   Compiling void v1.0.2
   Compiling vcell v0.1.3
   Compiling syn v1.0.109
   Compiling stable_deref_trait v1.2.0
   Compiling cortex-m-rt v0.6.15
   Compiling bitfield v0.13.2
   Compiling cortex-m-semihosting v0.3.7
   Compiling volatile-register v0.2.2
   Compiling cortex-m v0.6.7
   Compiling nb v0.1.3
   Compiling r0 v0.2.2
   Compiling embedded-hal v0.2.7
   Compiling py32f030_hello_world_start v0.1.0 (/Users/hunter/Desktop/tmp/tmp/py32f030_hello_world_start)
   Compiling panic-halt v0.2.0
   Compiling semver v0.9.0
   Compiling rustc_version v0.2.3
   Compiling generic-array v0.14.7
   Compiling bare-metal v0.2.5
   Compiling quote v1.0.37
   Compiling generic-array v0.13.3
   Compiling generic-array v0.12.4
   Compiling as-slice v0.1.5
   Compiling aligned v0.3.5
   Compiling cortex-m-rt-macros v0.6.15
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 8.98s

修改 memory.x , 指定 flash 和 ram 信息, 修改如下：

diff --git a/memory.x b/memory.x
index b271f22..0f0d381 100644
--- a/memory.x
+++ b/memory.x
@@ -2,9 +2,9 @@ MEMORY
 {
   /* NOTE 1 K = 1 KiBi = 1024 bytes */
   /* TODO Adjust these memory regions to match your device memory layout */
-  /* These values correspond to the LM3S6965, one of the few devices QEMU can emulate */
-  FLASH : ORIGIN = 0x00000000, LENGTH = 256K
-  RAM : ORIGIN = 0x20000000, LENGTH = 64K
+  /* PY32F030K28T6: */
+  FLASH : ORIGIN = 0x08000000, LENGTH = 64K
+  RAM : ORIGIN = 0x20000000, LENGTH = 8K
 }

 /* This is where the call stack will be allocated. */

修改編譯目標和運行命令

diff --git a/.cargo/config.toml b/.cargo/config.toml
index 9709a75..cb7fde1 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -2,6 +2,9 @@
# 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.thumbv6m-none-eabi]
+runner = 'probe-rs run --chip PY32F030x8'
+
 [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
@@ -28,8 +31,8 @@ rustflags = [

 [build]
# Pick ONE of these default compilation targets
-# target = "thumbv6m-none-eabi"        # Cortex-M0 and Cortex-M0+
-target = "thumbv7m-none-eabi"        # Cortex-M3
+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

如上修改后，執行 cargo r:

?  py32f030_hello_world_start git:(main) ? cargo r
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.01s
     Running `probe-rs run --chip PY32F030x8 target/thumbv6m-none-eabi/debug/py32f030_hello_world_start`
 WARN probe_rs::util::rtt: No RTT header info was present in the ELF file. Does your firmware run RTT?
      Erasing ? [00:00:00] [####################################] 4.00 KiB/4.00 KiB @ 53.93 KiB/s (eta 0s )
  Programming ? [00:00:00] [#####################################] 2.00 KiB/2.00 KiB @ 3.87 KiB/s (eta 0s )    Finished in 0.63s

cargo 將編譯工程，然后執行 runner 配置命令，即使用 probe-rs 命令下載固件到芯片，并執行。可以看到，下載完成成后并沒有其他日志打印，因此我們需要繼續添加打印日志。

添加日志 crate rtt-target ，讓日志打印像本地端一樣簡單。修改如下：

diff --git a/Cargo.toml b/Cargo.toml
index 1d1df47..a2b897d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,11 +6,13 @@ name = "py32f030_hello_world_start"
 version = "0.1.0"

 [dependencies]
-cortex-m = "0.6.0"
+cortex-m = { version = "0.7.6", features = ["critical-section-single-core"]}
 cortex-m-rt = "0.6.10"
 cortex-m-semihosting = "0.3.3"
 panic-halt = "0.2.0"

+rtt-target = "0.5.0"
+
# Uncomment for the panic example.
# panic-itm = "0.4.1"

添加 crate 后，在 main.rs 需要添加以下代碼：

diff --git a/src/main.rs b/src/main.rs
index 7922596..dbeaf9c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,18 +3,26 @@

 // pick a panicking behavior
 use panic_halt as _; // you can put a breakpoint on `rust_begin_unwind` to catch panics
-// use panic_abort as _; // requires nightly
-// use panic_itm as _; // logs messages over ITM; requires ITM support
-// use panic_semihosting as _; // logs messages to the host stderr; requires a debugger
+                     // use panic_abort as _; // requires nightly
+                     // use panic_itm as _; // logs messages over ITM; requires ITM support
+                     // use panic_semihosting as _; // logs messages to the host stderr; requires a debugger

 use cortex_m::asm;
 use cortex_m_rt::entry;

+use rtt_target::{rprintln, rtt_init_print};
+
#[entry]
 fn main() -> ! {
-    asm::nop(); // To not have main optimize to abort in release mode, remove when you add code
+    // init rtt
+    rtt_init_print!();
+
+    asm::nop();
+
+    rprintln!("Hello, world!");

     loop {
-        // your code goes here
+        // Wait For Interrupt
+        cortex_m::asm::wfi();
     }
 }

最后運行，下載完成后馬上打印 hello, world。在此，你已經成功踏入了嵌入式 Rust 的小門。

?  py32f030_hello_world_start git:(main) ? cargo r
   Compiling py32f030_hello_world_start v0.1.0 (/Users/hunter/Desktop/tmp/tttttt/py32f030_hello_world_start)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.10s
     Running `probe-rs run --chip PY32F030x8 target/thumbv6m-none-eabi/debug/py32f030_hello_world_start`
      Erasing ? [00:00:00] [##################################] 16.00 KiB/16.00 KiB @ 98.89 KiB/s (eta 0s )
  Programming ? [00:00:02] [###################################] 12.25 KiB/12.25 KiB @ 4.21 KiB/s (eta 0s )    Finished in 3.112s
Hello, world!

查看編譯信息

固件信息

Debug 模式

?  py32f030_hello_world_start git:(main) ? cargo size
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.01s
   text    data     bss     dec     hex filename
  12464       0    1088   13552    34f0 py32f030_hello_world_start

?  py32f030_hello_world_start git:(main) ? arm-none-eabi-readelf target/thumbv6m-none-eabi/debug/py32f030_hello_world_start -S
There are 22 section headers, starting at offset 0xbf9e4:

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] .vector_table     PROGBITS        08000000 0000f4 0000c0 00   A  0   0  4
  [ 2] .text             PROGBITS        080000c0 0001b4 002404 00  AX  0   0  4
  [ 3] .rodata           PROGBITS        080024c4 0025b8 000bec 00  AM  0   0  4
  [ 4] .data             PROGBITS        20000000 0031a4 000000 00   A  0   0  4
  [ 5] .bss              NOBITS          20000000 0031a4 000440 00  WA  0   0  4
  [ 6] .uninit           NOBITS          20000440 0031a4 000000 00  WA  0   0  4
  [ 7] .debug_abbrev     PROGBITS        00000000 0031a4 0024cf 00      0   0  1
  [ 8] .debug_info       PROGBITS        00000000 005673 02d143 00      0   0  1
  [ 9] .debug_aranges    PROGBITS        00000000 0327b6 001ab0 00      0   0  1
  [10] .debug_ranges     PROGBITS        00000000 034266 017248 00      0   0  1
  [11] .debug_str        PROGBITS        00000000 04b4ae 0443c6 01  MS  0   0  1
  [12] .comment          PROGBITS        00000000 08f874 00007b 01  MS  0   0  1
  [13] .ARM.attributes   ARM_ATTRIBUTES  00000000 08f8ef 000032 00      0   0  1
  [14] .debug_frame      PROGBITS        00000000 08f924 0057a8 00      0   0  4
  [15] .debug_line       PROGBITS        00000000 0950cc 0262da 00      0   0  1
  [16] .debug_loc        PROGBITS        00000000 0bb3a6 00027b 00      0   0  1
  [17] .debug_pubnames   PROGBITS        00000000 0bb621 0001e9 00      0   0  1
  [18] .debug_pubtypes   PROGBITS        00000000 0bb80a 000047 00      0   0  1
  [19] .symtab           SYMTAB          00000000 0bb854 0016b0 10     21 271  4
  [20] .shstrtab         STRTAB          00000000 0bcf04 0000e9 00      0   0  1
  [21] .strtab           STRTAB          00000000 0bcfed 0029f4 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  y (purecode), p (processor specific)

Release 模式

?  py32f030_hello_world_start git:(main) ? cargo size --release
    Finished `release` profile [optimized + debuginfo] target(s) in 0.01s
   text    data     bss     dec     hex filename
   1992       0    1088    3080     c08 py32f030_hello_world_start

?  py32f030_hello_world_start git:(main) ? arm-none-eabi-readelf target/thumbv6m-none-eabi/release/py32f030_hello_world_start -S
There are 22 section headers, starting at offset 0x1184c:

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] .vector_table     PROGBITS        08000000 0000f4 0000c0 00   A  0   0  4
  [ 2] .text             PROGBITS        080000c0 0001b4 0006ec 00  AX  0   0  4
  [ 3] .rodata           PROGBITS        080007ac 0008a0 00001c 00   A  0   0  4
  [ 4] .data             PROGBITS        20000000 0008bc 000000 00   A  0   0  4
  [ 5] .bss              NOBITS          20000000 0008bc 000440 00  WA  0   0  4
  [ 6] .uninit           NOBITS          20000440 0008bc 000000 00  WA  0   0  4
  [ 7] .debug_loc        PROGBITS        00000000 0008bc 0013d4 00      0   0  1
  [ 8] .debug_abbrev     PROGBITS        00000000 001c90 0009bc 00      0   0  1
  [ 9] .debug_info       PROGBITS        00000000 00264c 005097 00      0   0  1
  [10] .debug_aranges    PROGBITS        00000000 0076e3 000340 00      0   0  1
  [11] .debug_ranges     PROGBITS        00000000 007a23 000dc0 00      0   0  1
  [12] .debug_str        PROGBITS        00000000 0087e3 005524 01  MS  0   0  1
  [13] .comment          PROGBITS        00000000 00dd07 000048 01  MS  0   0  1
  [14] .ARM.attributes   ARM_ATTRIBUTES  00000000 00dd4f 000032 00      0   0  1
  [15] .debug_frame      PROGBITS        00000000 00dd84 000680 00      0   0  4
  [16] .debug_line       PROGBITS        00000000 00e404 0024c5 00      0   0  1
  [17] .debug_pubnames   PROGBITS        00000000 0108c9 0001e9 00      0   0  1
  [18] .debug_pubtypes   PROGBITS        00000000 010ab2 000047 00      0   0  1
  [19] .symtab           SYMTAB          00000000 010afc 0005c0 10     21  57  4
  [20] .shstrtab         STRTAB          00000000 0110bc 0000e9 00      0   0  1
  [21] .strtab           STRTAB          00000000 0111a5 0006a5 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  y (purecode), p (processor specific)

參考

hysonglet/py32f030_hello_world_start

cortex_m_quickstart - Rust (rust-embedded.org)

probe-rs - probe-rs

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