About STM32's GPIO port input/output data register

$OfftoSTM.\; 32ofGPthe\; IOterminalportinputinto/outputanumber\; ofdataregistersmemorydevice$

It used to be thought that the GPIO input data register and the output data register are completely separated and not related to each other, but today I discovered that they are connected somewhere. As follows: It

can be seen that if the output data register is set, it should have an impact on the input data register; and the connection state of the input data register is controlled by TTL Schmitt trigger.

Use the code written before to test the connection between the input data register and the outside, and get the value of GPIOx_IDR:

It is found that after setting the clock corresponding to GPIO, GPIOx_IDR has data, which means that GPIOx_IDR has been connected to the outside world at this moment.

When configured as input or output as follows:

emmm, I feel that this matter is purely personal curiosity, it doesn't seem to make much sense, used to pretend to be forced!