Sipeed NanoCluster集群风扇调速：猫头鹰风扇+PWM脚本优化

原装的风扇是5V，转起来有声音，买了猫头鹰4cm 5V PWM，用AI改了下fan_control.py；

用原来的fan_control.py脚本，猫头鹰风扇不会转，只有100%的时候才会转；用AI只是改了脚本；

Sipeed NanoCluster风扇降噪：PWM调速教程

Sipeed NanoCluster集群板风扇默认满速噪音大，可通过修改config.txt添加dtoverlay=pwm-2chan配置，重启后使用PWM sysfs接口调速（设置周期与占空比控制转速），并提供Python温控脚本实现基于温度（46°C启动，44°C停止，含迟滞与最小运行时间）的自动调速。

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fan_control.py 脚本代码

#!/usr/bin/env python3
"""
fan_control.py - 5V 风扇 PWM 调速控制
迟滞 + 最小运行时间，每 3 秒打印温度

- 温度 >= 46°C -> 风扇启动（20% 起步，按温度曲线调速）
- 温度 < 44°C -> 风扇停转（需满足最小运行时间）
- 44~46°C 之间保持当前状态
- 每 3 秒打印温度到 journal
"""

import time
import os

PWM_CHIP = '/sys/class/pwm/pwmchip0'
PWM_PATH = f'{PWM_CHIP}/pwm1'
PERIOD = 40000

TEMP_CURVE = [(46, 45), (50, 55), (55, 70), (60, 85), (65, 100)]

FAN_ON_TEMP = 46
FAN_OFF_TEMP = 44
MIN_RUN_SECONDS = 600

def setup_pwm():
    if os.path.exists(PWM_PATH):
        try:
            with open(f'{PWM_CHIP}/unexport', 'w') as f:
                f.write('1')
            time.sleep(0.1)
        except Exception as e:
            print(f'unexport warn: {e}')
    try:
        with open(f'{PWM_CHIP}/export', 'w') as f:
            f.write('1')
        time.sleep(0.3)
    except Exception as e:
        print(f'export err: {e}')
        return False
    for _ in range(20):
        if os.path.exists(f'{PWM_PATH}/period'):
            break
        time.sleep(0.1)
    if not os.path.exists(f'{PWM_PATH}/period'):
        print('PWM init failed')
        return False
    try:
        with open(f'{PWM_PATH}/period', 'w') as f:
            f.write(str(PERIOD))
        with open(f'{PWM_PATH}/enable', 'w') as f:
            f.write('1')
        return True
    except Exception as e:
        print(f'PWM cfg err: {e}')
        return False

def get_temp():
    try:
        with open('/sys/class/thermal/thermal_zone0/temp') as f:
            return float(f.read().strip()) / 1000.0
    except:
        return 50

def set_duty(pct):
    try:
        with open(f'{PWM_PATH}/duty_cycle', 'w') as f:
            f.write(str(int(PERIOD * pct / 100)))
    except Exception as e:
        print(f'duty err: {e}')

if not setup_pwm():
    time.sleep(3)
    if not setup_pwm():
        print('FATAL: PWM init failed')
        import sys; sys.exit(1)

fan_on = False
fan_start_time = 0
cur_duty = -1
print('fan-control started 5V PWM on>=46C off<44C min_run=600s')
while True:
    t = get_temp()

    if not fan_on and t >= FAN_ON_TEMP:
        fan_on = True
        fan_start_time = time.time()
        print(f'{t:.1f}C -> Fan ON (started, min run {MIN_RUN_SECONDS}s)')
    elif fan_on and t < FAN_OFF_TEMP:
        elapsed = time.time() - fan_start_time
        if elapsed >= MIN_RUN_SECONDS:
            fan_on = False
            print(f'{t:.1f}C -> Fan OFF (ran {elapsed:.0f}s)')

    if fan_on:
        d = 45
        for tt, dd in TEMP_CURVE:
            if t >= tt:
                d = dd
    else:
        d = 0

    if d != cur_duty:
        set_duty(d)
        cur_duty = d
        print(f'{t:.1f}C -> Fan {d}% [{"ON" if fan_on else "OFF"}]')

    state = 'ON' if fan_on else 'OFF'
    elapsed = time.time() - fan_start_time if fan_on else 0
    print(f'{t:.1f}C Fan={state}' + (f' run={elapsed:.0f}s' if fan_on else ''))
    time.sleep(3)