pyRPiRTC.py 文件源码

def _r_byte(self):
        """
        Read byte from the chip.

        :return: byte value
        :rtype: int
        """
        # data pin is now input (pull-down resistor embedded in chip)
        GPIO.setup(self._data_pin, GPIO.IN)
        # clock the byte from chip
        byte = 0
        for i in range(8):
            # make a high pulse on CLK pin
            GPIO.output(self._clk_pin, GPIO.HIGH)
            time.sleep(self.CLK_DELAY)
            GPIO.output(self._clk_pin, GPIO.LOW)
            time.sleep(self.CLK_DELAY)
            # chip out data on clk falling edge: store current bit into byte
            bit = GPIO.input(self._data_pin)
            byte |= ((2 ** i) * bit)
        # return byte value
        return byte