pw-embedded-c-style

pw-embedded-c-style

Embedded C code style assistant, based on a code style analysis of 302 .c files and 66 .h files from "Hands-On Learning of 51 Microcontrollers".

Default naming style: snake_case

Use cases

Applicable situations

Creating new embedded C projects (51 microcontrollers, STM32, etc.)
Optimizing the naming and structure of existing embedded code
Generating hardware driver modules (timers, serial ports, LCD, buttons, etc.)
Standardizing project file organization and code style
Learning best practices for embedded C programming

Inapplicable situations

General-purpose non-embedded C/C++ projects
Projects that require an RTOS or a complex architecture
Pure algorithm implementations (no hardware interaction)

Usage

Default naming style: snake_case

If camelCase is needed, explicitly state "use camelCase" in the instruction.

Create project

# 基础示例 (默认蛇形命名)
/pw-embedded-c-style 创建一个 LED 闪烁的项目

# 带外设的项目
/pw-embedded-c-style 创建一个带 LCD1602 显示和按键输入的项目

# 指定芯片
/pw-embedded-c-style 为 STM32F103 创建一个串口通信项目

# 明确指定使用驼峰命名
/pw-embedded-c-style 使用驼峰命名创建一个定时器项目

Optimize code

# 优化代码风格 (默认蛇形命名)
/pw-embedded-c-style 帮我优化这段按键扫描代码

# 重构模块
/pw-embedded-c-style 将这段代码重构为独立的驱动模块

# 添加注释
/pw-embedded-c-style 为这段定时器配置代码添加规范注释

# 使用驼峰命名优化
/pw-embedded-c-style 使用驼峰命名优化这段代码

Generate driver template

# 生成特定外设驱动
/pw-embedded-c-style 生成 DS1302 实时时钟驱动模板

# 生成通信协议
/pw-embedded-c-style 生成串口通信的收发缓冲区实现

Core conventions

Naming conventions

Default style: snake_case

// 函数: 蛇形命名
void config_timer0(unsigned int ms);
void lcd_write_cmd(unsigned char cmd);
void init_ds1302(void);

// 变量: 蛇形命名
unsigned char flag_500ms = 0;
unsigned char cnt_rxd = 0;

// 宏/常量: 全大写下划线
#define SYS_MCLK    (11059200/12)
#define LCD1602_RS  P1^0

// sbit: 全大写或蛇形
sbit LED = P0^0;
sbit EN_LED = P1^4;

Alternative style: camelCase/PascalCase

Use this style when the user explicitly requests it:

// 函数: 大驼峰
void ConfigTimer0(unsigned int ms);
void LcdWriteCmd(unsigned char cmd);
void InitDS1302(void);

// 变量: 小驼峰
unsigned char flag500ms = 0;
unsigned char cntRxd = 0;

// 宏/常量: 全大写下划线 (相同)
#define SYS_MCLK    (11059200/12)
#define LCD1602_RS  P1^0

// sbit: 全大写或大驼峰
sbit LED = P0^0;
sbit ENLED = P1^4;

Code organization

Single-file project

#include <reg52.h>

// 宏定义
// sbit 定义
// 全局变量
// 函数声明

void main() { }
// 函数实现
// 中断函数

Multi-file project

config.h    - 全局配置 (类型定义、系统参数、IO 定义)
module.h    - 模块头文件 (结构体、extern 声明、函数声明)
module.c    - 模块实现 (#define _MODULE_C)
main.c      - 主程序

Common patterns

Timer configuration

void config_timer0(unsigned int ms)
{
    unsigned long tmp;
    tmp = 11059200 / 12;
    tmp = (tmp * ms) / 1000;
    tmp = 65536 - tmp;
    tmp = tmp + 12;
    T0RH = (unsigned char)(tmp>>8);
    T0RL = (unsigned char)tmp;
    TMOD &= 0xF0;
    TMOD |= 0x01;
    TH0 = T0RH;
    TL0 = T0RL;
    ET0 = 1;
    TR0 = 1;
}

Interrupt service routine

void interrupt_timer0() interrupt 1
{
    static unsigned char tmr_500ms = 0;
    TH0 = T0RH;
    TL0 = T0RL;
    if (++tmr_500ms >= 50)
    {
        tmr_500ms = 0;
        flag_500ms = 1;
    }
}

Flag-driven

bit flag_500ms = 0;

// 中断中设置
flag_500ms = 1;

// 主循环检测
while (1)
{
    if (flag_500ms)
    {
        flag_500ms = 0;
        // 执行任务
    }
}

Button debouncing

void key_scan(void)
{
    static unsigned char keybuf[4] = {0xFF, 0xFF, 0xFF, 0xFF};
    keybuf[i] = (keybuf[i] << 1) | KEY_IN[i];
    if ((keybuf[i] & 0x0F) == 0x00)
        key_sta[i] = 0;  // 稳定按下
}

Lookup table method

unsigned char code led_char[] = {
    0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x82, 0xF8,
    0x80, 0x90, 0x88, 0x83, 0xC6, 0xA1, 0x86, 0x8E
};
P0 = led_char[num];

Comment style

/* 文件头注释 */
/*
*******************************************************************************
* 文件名称: main.c
* 描  述: 功能描述
* 版本号: v1.0.0
*******************************************************************************
*/

/* 函数注释 */
void lcd_show_str(unsigned char x, unsigned char y,
                  unsigned char *str, unsigned char len)

// 行内注释
EA = 1;                     // 使能总中断
config_timer0(10);          // 配置 T0 定时 10ms

Code style characteristics

Concise and direct, avoid over-abstraction
Directly manipulate hardware registers
Use sbit to define IO ports
Specify interrupt vector numbers directly (interrupt 1)
Storage area modifiers (code, pdata)
Flag-driven main loop
Use lookup tables to handle data mapping

Best practices

Naming style selection

Use snake_case by default:

Matches the style of the Linux kernel and most open-source embedded projects
Word separation is obvious, readability is good
Suitable for production projects and team collaboration

Scenarios for using camelCase/PascalCase:

Teaching projects or reference textbooks use camelCase
The team explicitly requires the use of camelCase
Needs to remain consistent with existing camelCase code

Important principle: the entire project must use a unified naming style

Project creation recommendations

Single-file project: suitable for simple functions (LED blinking, button detection, etc.)
Multi-file project: suitable for coordination of multiple peripherals (LCD + buttons + serial port, etc.)
Modular drivers: each peripheral is an independent .h/.c file pair

Code optimization recommendations

Naming conventions: use snake_case by default (functions/variables), and use all-uppercase underscores for macros
Interrupt minimization: interrupt functions only set flag bits, the main loop handles business logic
Hardware abstraction: use macro definitions to isolate hardware-related code, facilitating portability
Clear comments: key register configurations must have inline comments added

Common error handling

Problem 1: Inaccurate timer

// 错误: 未考虑指令周期补偿
tmp = 65536 - tmp;

// 正确: 加上补偿值
tmp = 65536 - tmp;
tmp = tmp + 12;  // 补偿中断响应延迟

Problem 2: Key debouncing

// 错误: 直接读取按键状态
if (KEY == 0) { /* 处理 */ }

// 正确: 使用移位寄存器消抖
keybuf = (keybuf << 1) | KEY;
if ((keybuf & 0x0F) == 0x00) { /* 稳定按下 */ }

Problem 3: Global variable conflicts

// 错误: 多个模块使用相同变量名
unsigned char flag;  // 在多个 .c 文件中定义

// 正确: 使用模块前缀或 static
static unsigned char uart_flag;  // 仅本文件可见
extern unsigned char g_system_flag;  // 全局共享

Precautions

Interrupt functions must return as soon as possible to avoid long occupation
When global variables are shared between interrupts and the main loop, use the volatile qualifier
Large arrays use the code modifier to be stored in ROM, saving RAM
Do not call delay functions in interrupts
Multi-file projects must use extern to correctly declare global variables

Technical parameter description

Supported chip platforms

51 series: AT89C51, STC89C52, STC15, etc.
STM32 series: F103, F407, etc. (register definitions need adjustment)
Other 8051-compatible chips

Source of code standards

Based on the actual teaching project of "Teach You 51 Microcontroller Step by Step":

302 .c source files
66 .h header files
Covers 20+ common peripheral drivers
Snake case is used by default, which better conforms to embedded C project standards

Output format

Single-file project: generate main.c
Multi-file project: generate config.h, module.h, module.c, main.c
Driver module: generate driver.h, driver.c

Example scenarios

Scenario 1: Rapid prototype verification

User requirement: "Create a program where an LED blinks once per second"

Assistant output:

A single main.c file
Includes timer configuration and interrupt function
Uses flag bits to drive LED toggling

Scenario 2: Modular project

User requirement: "Create a project with LCD1602 displaying temperature and key adjustment"