smbus2.py 文件源码

def read_i2c_block_data(self, i2c_addr, register, length):
        # type: (int, int, int) -> list
        """
        Read a block of byte data from a given register
        :rtype: list
        :param i2c_addr: i2c address
        :param register: Start register
        :param length: Desired block length
        :return: List of bytes
        """
        if length > I2C_SMBUS_BLOCK_MAX:
            raise ValueError("Desired block length over %d bytes" % I2C_SMBUS_BLOCK_MAX)
        self._set_address(i2c_addr)
        msg = i2c_smbus_ioctl_data.create(
            read_write=I2C_SMBUS_READ, command=register, size=I2C_SMBUS_I2C_BLOCK_DATA
        )
        msg.data.contents.byte = length
        ioctl(self.fd, I2C_SMBUS, msg)
        return msg.data.contents.block[1:length+1]