VHDL:信号和端口在“箭头"的哪一侧?=> [英] VHDL: signals and ports on which side of the "arrow" =>

问题描述

非常基本的问题:

我怎么知道端口/信号/值应该放在箭头的哪一边?我注意到通过切换 port_a =>x 到 x< = port_a 似乎很相等，我得到了一个错误.另外， x =>port_a 不起作用

How do I know where the port/signal/value should be placed on which side of the arrows? I noticed that by switching port_a => x to x <= port_a which seems very equal, I got an error. Also, x => port_a dont work

我什至不知道箭头应该指向哪个方向.

I even do not know which way the arrows should point.

非常感谢您的答复！

推荐答案

< = 是一种分配-尤其是信号分配，从其他地方驱动带有值的信号.从物理上讲，右手边的东西将值驱动到左手边.

<= is an assignment - specifically a signal assignment, driving a signal with a value from somewhere else. For a physical analogy, the thing on the right hand side drives a value onto the left hand side.

=> 是从引脚到信号的端口映射.这不是一项任务-物理上的类比可能是将引脚焊接到电线上.

=> is a port mapping from a pin to a signal. This is not an assignment - the physical analogy might be soldering a pin to a wire.

您只能对实例进行焊接"，因此 => 映射仅发生在 port map 内部.在那里，大头针"总是 放在左侧(因为这是语言规则所说的)，这就是为什么您不能在键盘上执行 x< = port_a 的原因港口地图.

You can only do "soldering" to instantiations, so => mapping only happens inside a port map. And there, "pins" always go on the left (because that's what the language rules say), which is why you can't do x <= port_a in a port map.

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