from machine import I2C, Pin

# 硬件 I2C
i2c = I2C(0, sda=Pin(20), scl=Pin(21), freq=400000)

# 软件 I2C (SoftI2C)
from machine import SoftI2C
i2c_soft = SoftI2C(sda=Pin(20), scl=Pin(21), freq=100000)

'''
实验：扫描 I2C 总线
'''
devices = i2c.scan()

print(f"发现 {len(devices)} 个设备:")
for addr in devices:
    print(f"  地址: 0x{addr:02X} ({addr})")

# 写入数据
i2c.writeto(addr, bytes([data]))

# 写入寄存器
i2c.writeto_mem(addr, reg, bytes([data]))

# 读取数据
data = i2c.readfrom(addr, num_bytes)

# 读取寄存器
data = i2c.readfrom_mem(addr, reg, num_bytes)

# ADXL345 寄存器
ADXL345_ADDR = 0x53
REG_DEVID = 0x00
REG_POWER_CTL = 0x2D
REG_DATA_FORMAT = 0x31
REG_DATAX0 = 0x32  # X 轴低字节
REG_DATAX1 = 0x33  # X 轴高字节
# Y, Z 依次递增

'''
实验：ADXL345 I2C 通信
'''
from machine import I2C, Pin
import time

i2c = I2C(0, sda=Pin(20), scl=Pin(21), freq=400000)

ADXL345_ADDR = 0x53

def write_reg(reg, value):
    i2c.writeto_mem(ADXL345_ADDR, reg, bytes([value]))

def read_reg(reg, length=1):
    return i2c.readfrom_mem(ADXL345_ADDR, reg, length)

def init_adxl345():
    """初始化 ADXL345"""
    # 检查设备 ID
    dev_id = read_reg(0x00, 1)[0]
    if dev_id != 0xE5:
        print(f"设备 ID 错误: 0x{dev_id:02X}")
        return False
    
    # 设置数据格式: ±2g, 全分辨率
    write_reg(0x31, 0x08)
    
    # 启用测量模式
    write_reg(0x2D, 0x08)
    
    return True

def read_xyz():
    """读取三轴加速度"""
    data = read_reg(0x32, 6)
    
    # 解析数据（小端序，有符号）
    x = int.from_bytes(data[0:2], 'little', True)
    y = int.from_bytes(data[2:4], 'little', True)
    z = int.from_bytes(data[4:6], 'little', True)
    
    # 转换为 g (±2g 范围，灵敏度 3.9mg/LSB)
    return x * 0.0039, y * 0.0039, z * 0.0039

# 初始化
if init_adxl345():
    print("ADXL345 初始化成功")
    
    while True:
        x, y, z = read_xyz()
        print(f"X: {x:+.2f}g  Y: {y:+.2f}g  Z: {z:+.2f}g")
        time.sleep(0.2)

def decode_twos_complement(data, bits=16):
    """
    二进制补码解码
    data: 原始字节数组 [低字节, 高字节]
    """
    value = data[0] | (data[1] << 8)
    
    # 如果最高位为 1，则为负数
    if value & (1 << (bits - 1)):
        value -= (1 << bits)
    
    return value

# 示例
raw = [0x5E, 0xFF]  # -162 的补码
value = decode_twos_complement(raw)
print(f"解码值: {value}")  # -162

def bcd_to_dec(bcd):
    """BCD 转十进制"""
    return (bcd >> 4) * 10 + (bcd & 0x0F)

def dec_to_bcd(dec):
    """十进制转 BCD"""
    return ((dec // 10) << 4) | (dec % 10)

'''
实验：DS1307 实时时钟
'''
from machine import I2C, Pin
import time

i2c = I2C(0, sda=Pin(20), scl=Pin(21))
DS1307_ADDR = 0x68

def bcd_to_dec(bcd):
    return (bcd >> 4) * 10 + (bcd & 0x0F)

def dec_to_bcd(dec):
    return ((dec // 10) << 4) | (dec % 10)

def read_time():
    """读取当前时间"""
    data = i2c.readfrom_mem(DS1307_ADDR, 0x00, 7)
    
    sec = bcd_to_dec(data[0] & 0x7F)
    min = bcd_to_dec(data[1])
    hour = bcd_to_dec(data[2] & 0x3F)
    day = bcd_to_dec(data[4])
    month = bcd_to_dec(data[5])
    year = bcd_to_dec(data[6]) + 2000
    
    return (year, month, day, hour, min, sec)

def set_time(year, month, day, hour, min, sec):
    """设置时间"""
    data = bytes([
        dec_to_bcd(sec),
        dec_to_bcd(min),
        dec_to_bcd(hour),
        1,  # 星期
        dec_to_bcd(day),
        dec_to_bcd(month),
        dec_to_bcd(year - 2000)
    ])
    i2c.writeto_mem(DS1307_ADDR, 0x00, data)

# 设置时间（首次使用）
# set_time(2026, 4, 10, 23, 30, 0)

while True:
    t = read_time()
    print(f"{t[0]}-{t[1]:02d}-{t[2]:02d} {t[3]:02d}:{t[4]:02d}:{t[5]:02d}")
    time.sleep(1)

'''
检测 I2C 地址冲突
'''
def check_address_conflict():
    devices = i2c.scan()
    
    # 已知设备地址
    known_devices = {
        0x53: 'ADXL345',
        0x68: 'DS1307',
        0x3C: 'SSD1306 OLED',
        0x3F: 'LCD1602 (PCF8574)',
        0x27: 'LCD1602 (PCF8574A)',
    }
    
    for addr in devices:
        name = known_devices.get(addr, '未知设备')
        print(f"0x{addr:02X}: {name}")

'''
同时使用多个 I2C 设备
'''
class I2CDeviceManager:
    def __init__(self, i2c):
        self.i2c = i2c
        self.devices = {}
    
    def register_device(self, name, addr):
        if addr in self.i2c.scan():
            self.devices[name] = addr
            print(f"注册设备: {name} @ 0x{addr:02X}")
        else:
            print(f"设备未找到: {name} @ 0x{addr:02X}")
    
    def write(self, name, reg, data):
        if name in self.devices:
            self.i2c.writeto_mem(self.devices[name], reg, bytes([data]))
    
    def read(self, name, reg, length):
        if name in self.devices:
            return self.i2c.readfrom_mem(self.devices[name], reg, length)
        return None

# 使用
manager = I2CDeviceManager(i2c)
manager.register_device('accel', 0x53)
manager.register_device('rtc', 0x68)

# 检查清单:
# 1. 接线是否正确 (SDA/SCL 是否接反)
# 2. 上拉电阻是否存在 (通常模块自带)
# 3. 供电电压是否正确
# 4. I2C 地址是否正确

# 尝试更低频率
i2c = I2C(0, sda=Pin(20), scl=Pin(21), freq=100000)

# 增加超时时间
try:
    data = i2c.readfrom_mem(addr, reg, length)
except OSError as e:
    print(f"I2C 错误: {e}")
    # 尝试重新初始化
    i2c.init()