How does a microcontroller detect a high level?-EEWORLD

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The problem of IO port detection high point level has troubled me for a long time.

I have been working on a project these days and I feel a little dizzy. I have checked a lot of information and made a summary to share with you:

1. To detect the high and low levels of the I/O port of the 51 single-chip microcomputer, it is necessary to first set the port to 1. Only then is the pin set to input.

2. If it is an AVR microcontroller, you can set the input and output by setting the value of DDRx (see the data sheet for details~~)

3. Do not set the detection port of the microcontroller as input, otherwise it may affect the voltage of the port of the detected module (such as: being pulled down to 0v, or being pulled up)

4. Note that the microcontroller is generally in TTL level mode, so the lowest high level should be 2V, and the highest low level should be 0.8V. (It is safer to refer to the data sheet for details)

Keywords：MCU Reference address：How does a microcontroller detect a high level?

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