RUST编写CH347命令行工具

这几天在学习rust，就想着用rust写一个命令行工具，用来操作CH347芯片。之前已经用python实现了ch347的spi、iic通信接口，相比之下，rust链接c库的方式更加简单，所以就用rust来实现这个工具。

之前的文章：

1. python封装动态库实例
2. 调试利器CH347
3. CH347连接MPU6050
4. CH347读写SPI Flash
5. CH347读取MPU6050数据和显示

Rust编写的命令行还没有完全实现，今天记录一个小功能。仓库地址👉 https://github.com/pengwon/ch347-rs

在python版中，没有将gpio和jtag功能封装，这次用rust实现时优先搞了这两个功能。然后用rust实现了一个pwm。

gpio在驱动库中的函数很简单，主要就两个：

/***************GPIO********************/
// Get the GPIO direction and pin level of CH347
BOOL WINAPI CH347GPIO_Get(ULONG iIndex,
                          UCHAR *iDir,   // Pin direction: GPIO0-7 corresponding bit0-7, 0: input; 1: output
                          UCHAR *iData); // GPIO0 level: GPIO0-7 corresponding bit0-7, 0: low level; 1: high level

// Set the GPIO direction and pin level of CH347
BOOL WINAPI CH347GPIO_Set(ULONG iIndex,		  // Specify device serial number
                          UCHAR iEnable,      // Data valid flag: corresponding bit0-7, correspond to GPIO0-7.
                          UCHAR iSetDirOut,   // Sets I/O direction, A bit is 0 means corresponding pin is input, a bit is 1 means corresponding pin is output. GPIO0-7 corresponds to bit0-7.
                          UCHAR iSetDataOut); // Output data. If I/O direction is output, then a pin outputs low level when a bit cleared to 0, a pin outputs high level when a bit set to 1

在rust中绑定如下：

use libc::{c_int, c_uchar, c_ulong};

#[link(name = "ch347")]
extern "C" {
    fn CH347GPIO_Get(fd: c_ulong, iDir: *mut c_uchar, iData: *mut c_uchar) -> c_int;
    fn CH347GPIO_Set(
        fd: c_ulong,
        iEnable: c_uchar,
        iSetDirOut: c_uchar,
        iSetDataOut: c_uchar,
    ) -> c_int;
}

pub fn gpio_get(fd: u32, dir: &mut u8, data: &mut u8) -> bool {
    unsafe {
        CH347GPIO_Get(
            fd,
            dir as *mut u8 as *mut c_uchar,
            data as *mut u8 as *mut c_uchar,
        ) != 0
    }
}

pub fn gpio_set(fd: u32, enable: u8, set_dir_out: u8, set_data_out: u8) -> bool {
    unsafe {
        CH347GPIO_Set(
            fd,
            enable as c_uchar,
            set_dir_out as c_uchar,
            set_data_out as c_uchar,
        ) != 0
    }
}

PWM功能是这样实现的：

pub fn cmd_gpio_pwm(matches: &ArgMatches) {
    let fd = *matches.get_one::<u32>("fd").unwrap();
    let channel = *matches.get_one::<u8>("channel").unwrap();
    let frequency = *matches.get_one::<u32>("frequency").unwrap();
    let duty_cycle = *matches.get_one::<u8>("duty_cycle").unwrap();
    let pulse_count = *matches.get_one::<u32>("pulse_count").unwrap();

    // 调用设置 PWM 的函数（假设存在）
    open_device(fd);
    if !set_pwm(fd, channel, frequency, duty_cycle, pulse_count) {
        eprintln!("Failed to set PWM");
    }
}

fn set_pwm(fd: u32, channel: u8, frequency: u32, duty_cycle: u8, pulse_count: u32) -> bool {
    let enable = 1 << channel; // 启用 GPIO
    let dir_out = 1 << channel; // 设置为输出
    let data_out = 1 << channel;

    let period = 1_000_000 / frequency; // 周期时间（微秒）
    let high_time = period * duty_cycle as u32 / 100; // 高电平时间（微秒）
    let low_time = period - high_time; // 低电平时间（微秒）

    for _ in 0..pulse_count {
        // 设置高电平
        if !gpio_set(fd, enable, dir_out, data_out) {
            return false;
        }
        thread::sleep(Duration::from_micros(high_time as u64));

        // 设置低电平
        if !gpio_set(fd, enable, dir_out, !data_out) {
            return false;
        }
        thread::sleep(Duration::from_micros(low_time as u64));
    }

    // 如果脉冲数为 0，则连续输出
    if pulse_count == 0 {
        loop {
            // 设置高电平
            if !gpio_set(fd, enable, dir_out, data_out) {
                return false;
            }
            thread::sleep(Duration::from_micros(high_time as u64));

            // 设置低电平
            if !gpio_set(fd, enable, dir_out, !data_out) {
                return false;
            }
            thread::sleep(Duration::from_micros(low_time as u64));
        }
    }

    true
}

这个版本只实现了单一通道进行测试，在Windows10上，频率到1kHz，频率波动就很大了，实测在600Hz到750Hz之间，占空比相对来说误差还不算大。目前还没在Linux上测试。

在终端中输入以下命令进行测试：

cargo run --bin ch347-cli --  gpio pwm --channel 3 --frequency 1000 --duty-cycle 40 --pulse-count 10

输出波形：

测试下来，准确肯定是谈不上了，可以临时应个急。