Select 来自 16 位宽寄存器的一个引脚，python

Question

[输入]:

地址：0x001c，16 位宽。

重置：0x0

这是 PIN 16..31 的位域寄存器。

[问题]: 我怎么能 select PIN 17?

[我的解决方案]：这样做正确吗：

def select_pin(pin):
    lowstate = 0x0000
    highstate = 0x001c
    pin_hex = int(str(pin), 16)
    responsive = highstate-pin_hex
    inverted = hex(responsive ^ 0xFFFF)
    print(inverted)

select_pin(17)

老实说，我在这方面存在理论上的差距，我什至不确定如何表达我的问题以在 Google 中找到有关它的一些信息，任何帮助将不胜感激。

Answer 1

位掩码只是 2**pin 整数表示法。

如果您有

的 "register" 二进制文件

# alternating increasing amounts of 0/1
reg = int("10110011100011110000111110000010",2)  # 4294967295

def get_pin(value, pin):
    return 1 if (value & 2**pin) > 0 else 0 

for p in range(33):
    print(f"{2**p:>10} is {get_pin(reg,p)}")

         1 is 0
         2 is 1
         4 is 0
         8 is 0
        16 is 0
        32 is 0
        64 is 0
       128 is 1
       256 is 1
       512 is 1
      1024 is 1
      2048 is 1
      4096 is 0
      8192 is 0
     16384 is 0
     32768 is 0
     65536 is 1
    131072 is 1
    262144 is 1
    524288 is 1
   1048576 is 0
   2097152 is 0
   4194304 is 0
   8388608 is 1
  16777216 is 1
  33554432 is 1
  67108864 is 0
 134217728 is 0
 268435456 is 1
 536870912 is 1
1073741824 is 0
2147483648 is 1

Answer 2

假设（寄存器）值位代表引脚值，其中每个引脚号代表位来自 LSB 的索引 -> MSB（从右到左），你所要做的就是一个简单的位和之间：

价值
掩码只有一个位设置（在所需引脚的位置），而所有其他都被重置

提取您感兴趣的 bit (pin) 值：

>>> reg = 0x001C0000  # Hi Word, Lo Word
>>>
>>> reg_bin_repr = "{0:032b}".format(0x001C0000)  # For visualization purposes only
>>> reg_bin_repr
'00000000000111000000000000000000'
>>>
>>> for idx, val in enumerate(reversed(reg_bin_repr)):  # Each bit with its value (right -> left)
...     print("Bit (pin) {0:02d}: {1:s}".format(idx, val))
...
Bit (pin) 00: 0
Bit (pin) 01: 0
Bit (pin) 02: 0
Bit (pin) 03: 0
Bit (pin) 04: 0
Bit (pin) 05: 0
Bit (pin) 06: 0
Bit (pin) 07: 0
Bit (pin) 08: 0
Bit (pin) 09: 0
Bit (pin) 10: 0
Bit (pin) 11: 0
Bit (pin) 12: 0
Bit (pin) 13: 0
Bit (pin) 14: 0
Bit (pin) 15: 0
Bit (pin) 16: 0
Bit (pin) 17: 0
Bit (pin) 18: 1
Bit (pin) 19: 1
Bit (pin) 20: 1
Bit (pin) 21: 0
Bit (pin) 22: 0
Bit (pin) 23: 0
Bit (pin) 24: 0
Bit (pin) 25: 0
Bit (pin) 26: 0
Bit (pin) 27: 0
Bit (pin) 28: 0
Bit (pin) 29: 0
Bit (pin) 30: 0
Bit (pin) 31: 0
>>>
>>> # And the function
>>> def pin_value(register_value, pin_number):
...     return 1 if register_value & (1 << pin_number) else 0
...
>>>
>>> pin_value(reg, 17)
0
>>> pin_value(reg, 18)
1

附带说明一下，在处理数字时，您不必将它们转换为相同的基数，将其转换为不同的基数时值不会改变，只有它的表示形式会：

>>> i0 = 1
>>> i1 = 0x19
>>>
>>> i0 + i1
26
>>> i1
25
>>> hex(i1)
'0x19'
>>> int(hex(i1), 16)
25

Select 来自 16 位宽寄存器的一个引脚，python

Select one pin from 16 bits wide register, python

python

hex

bit

python-3.x