w25Q256的micropython驱动程序

由于w25Q256芯片是SPI闪存，需要使用micropython的SPI模块进行驱动。

以下是一个简单的驱动程序示例：

import machine
import time

# 定义SPI总线
spi = machine.SPI(1, baudrate=20000000, polarity=0, phase=0)

# 定义w25Q256的命令字
CMD_WRITE_ENABLE = 0x06
CMD_WRITE_DISABLE = 0x04
CMD_READ_STATUS_REG = 0x05
CMD_WRITE_STATUS_REG = 0x01
CMD_READ_DATA = 0x03
CMD_PAGE_PROGRAM = 0x02
CMD_ERASE_SECTOR = 0x20
CMD_ERASE_BLOCK = 0xD8
CMD_ERASE_CHIP = 0xC7

# 读取状态寄存器
def read_status_reg():
    spi.write(bytes([CMD_READ_STATUS_REG]))
    return spi.read(1)[0]

# 写入状态寄存器
def write_status_reg(value):
    spi.write(bytes([CMD_WRITE_STATUS_REG, value]))

# 写使能
def write_enable():
    spi.write(bytes([CMD_WRITE_ENABLE]))

# 写禁止
def write_disable():
    spi.write(bytes([CMD_WRITE_DISABLE]))

# 擦除扇区
def erase_sector(addr):
    write_enable()
    spi.write(bytes([CMD_ERASE_SECTOR, addr >> 16, addr >> 8, addr]))
    while read_status_reg() & 0x01:
        time.sleep_ms(1)

# 擦除整个芯片
def erase_chip():
    write_enable()
    spi.write(bytes([CMD_ERASE_CHIP]))
    while read_status_reg() & 0x01:
        time.sleep_ms(1)

# 读取数据
def read_data(addr, length):
    spi.write(bytes([CMD_READ_DATA, addr >> 16, addr >> 8, addr]))
    return spi.read(length)

# 写入数据
def write_data(addr, data):
    write_enable()
    spi.write(bytes([CMD_PAGE_PROGRAM, addr >> 16, addr >> 8, addr]))
    spi.write(data)
    write_disable()

# 测试代码
spi_cs = machine.Pin(0, machine.Pin.OUT)
spi_cs.value(1)

# 擦除整个芯片
erase_chip()

# 写入数据
data_to_write = b'hello world'
write_data(0, data_to_write)

# 读取数据
data_read = read_data(0, len(data_to_write))
print('Data read:', data_read)

需要根据具体的硬件连接方式和芯片数据手册的要求进行相应的修改。