'''
实验：霍尔传感器检测磁场
接线：S 端连接 GP5
'''
from machine import Pin
import time

hall = Pin(5, Pin.IN)

while True:
    if hall.value() == 0:
        print("检测到南极磁场!")
    else:
        print("无磁场或北极磁场")
    time.sleep(0.1)

'''
实验：霍尔编码器（测转速）
在旋转轴上安装多极磁铁
'''
from machine import Pin
import time

hall = Pin(5, Pin.IN)

POLES = 4  # 磁极数量
pulse_count = 0
last_state = 1

def count_pulses(duration_ms=1000):
    global pulse_count, last_state
    pulse_count = 0
    start = time.ticks_ms()
    
    while time.ticks_diff(time.ticks_ms(), start) < duration_ms:
        current = hall.value()
        if current == 0 and last_state == 1:
            pulse_count += 1
        last_state = current
    
    return pulse_count

while True:
    pulses = count_pulses(1000)
    rpm = (pulses / POLES) * 60
    print(f"脉冲数: {pulses}, 转速: {rpm:.1f} RPM")

'''
实验：干簧管磁场检测
接线：S 端连接 GP18
'''
from machine import Pin
import time

reed = Pin(18, Pin.IN)

while True:
    if reed.value() == 0:
        print("检测到磁场!")
    else:
        print("无磁场")
    time.sleep(0.1)

'''
实验：门窗磁性报警器
干簧管安装在门框，磁铁安装在门上
'''
from machine import Pin
import time

reed = Pin(18, Pin.IN)
buzzer = Pin(20, Pin.OUT)
led = Pin(0, Pin.OUT)

armed = True  # 布防状态

def alarm():
    """触发报警"""
    for _ in range(10):
        buzzer.value(1)
        led.value(1)
        time.sleep(0.2)
        buzzer.value(0)
        led.value(0)
        time.sleep(0.2)

while True:
    if armed:
        if reed.value() == 1:  # 磁铁离开（门打开）
            print("警报！门被打开！")
            alarm()
    time.sleep(0.1)

'''
实验：自行车码表
干簧管装在车架，磁铁装在车轮
'''
from machine import Pin
import time

reed = Pin(18, Pin.IN)

WHEEL_CIRCUMFERENCE = 2.1  # 轮周长（米）

pulse_count = 0
total_distance = 0
last_state = 1
last_pulse_time = 0

def calculate_speed():
    """计算即时速度（km/h）"""
    global last_pulse_time
    
    current_time = time.ticks_ms()
    interval = time.ticks_diff(current_time, last_pulse_time)
    
    if interval > 0:
        speed = (WHEEL_CIRCUMFERENCE / interval) * 3600  # m/ms → km/h
        last_pulse_time = current_time
        return speed
    return 0

while True:
    current = reed.value()
    
    if current == 0 and last_state == 1:
        pulse_count += 1
        total_distance += WHEEL_CIRCUMFERENCE / 1000  # 转换为公里
        speed = calculate_speed()
        print(f"速度: {speed:.1f} km/h | 里程: {total_distance:.2f} km")
    
    last_state = current
    time.sleep_ms(1)

'''
实验：三相无刷电机霍尔换相
'''
from machine import Pin
import time

# 三个霍尔传感器
hall_a = Pin(5, Pin.IN)
hall_b = Pin(6, Pin.IN)
hall_c = Pin(7, Pin.IN)

# 换相表
COMMUTATION_TABLE = {
    0b001: "相序 1",
    0b011: "相序 2",
    0b010: "相序 3",
    0b110: "相序 4",
    0b100: "相序 5",
    0b101: "相序 6",
}

def get_hall_state():
    """读取霍尔状态"""
    a = hall_a.value()
    b = hall_b.value()
    c = hall_c.value()
    return (a << 2) | (b << 1) | c

last_state = 0

while True:
    state = get_hall_state()
    
    if state != last_state:
        phase = COMMUTATION_TABLE.get(state, "无效状态")
        print(f"霍尔: {state:03b} → {phase}")
        last_state = state
    
    time.sleep_ms(1)

'''
实验：模拟霍尔传感器（如有）
输出电压与磁场强度成比例
'''
from machine import ADC
import time

hall_analog = ADC(26)

# 无磁场时的中点电压
ZERO_GAUSS_VOLTAGE = 1.65  # 通常为 VCC/2

def read_gauss():
    """读取磁场强度（高斯）"""
    raw = hall_analog.read_u16()
    voltage = raw * 3.3 / 65535
    
    # 典型灵敏度: 1.4 mV/Gs
    gauss = (voltage - ZERO_GAUSS_VOLTAGE) / 0.0014
    return gauss

while True:
    gauss = read_gauss()
    print(f"磁场强度: {gauss:.1f} Gs")
    time.sleep(0.2)

'''
软件滤波抗干扰
'''
from machine import Pin
import time

hall = Pin(5, Pin.IN)

def read_with_filter(samples=5, delay_ms=2):
    """多次采样滤波"""
    count = 0
    for _ in range(samples):
        count += hall.value()
        time.sleep_ms(delay_ms)
    
    # 多数表决
    return 1 if count > samples // 2 else 0

while True:
    filtered = read_with_filter()
    print(f"滤波后状态: {filtered}")
    time.sleep(0.1)