What does the AFEN bit of the APB register of GD32F103 mean? What does the IO port backup function mean?

Xuehs

What does the AFEN bit of the APB register of GD32F103 mean? What does the IO port backup function mean? [Copy link]

The above picture is a screenshot of the AFEN bit of the APB register of GD32F103 in the user manual. The literal meaning should be to turn on this clock when the IO port needs to be multiplexed, and not to turn it on when it is not needed. However, when I use the routine 03_EXTI_Key_Interrupt_mode of GD32103E-EVAL, neither IO port is multiplexed. Why do I need to enable this clock? If this clock is turned off, the routine cannot run normally. I don't understand the function of this bit, and I look forward to enthusiastic experts to teach me.

Also, does the "Alternate Function (AF) Configuration" in the user manual mean reuse?

lugl4313820

Multiplexing should mean multiplexing this IO into peripherals other than GPIO. You can take a look at the GPIO diagram to understand it better.

humancat01

I support domestic chips, and I hope everyone will support domestic chips

dryhq

Look at the internal structure and register definition

Xuehs

lugl4313820 posted on 2024-5-14 18:00 Multiplexing should be to reuse this IO as a peripheral other than GPIO. If you look at the GPIO diagram, you may understand it better.

My understanding is that when the IO port is occupied by a peripheral, it is set to multiplexing mode. However, when I look at his routines, the multiplexing clock needs to be enabled when the IO port is used as an external interrupt, but the IO port is not in multiplexing mode. When the IO port is used as UART communication, the IO port is set to multiplexing mode, but the multiplexing clock is not started.

lugl4313820

Xuehs posted on 2024-5-15 17:43 My understanding is that when it is occupied by peripherals, it is set to multiplexing mode, but when I look at his routine, the IO port needs to enable multiplexing clock when it is used as an external interrupt, but the IO ...

It seems that both the multiplexed clock and the GPIO clock need to be turned on. You'd better use a register to light a lamp, so that you will understand it more deeply and remember it.

damiaa

lugl4313820 posted on 2024-5-14 18:00 Multiplexing should be to reuse this IO as a peripheral other than GPIO. If you look at the GPIO diagram, you may understand it better.

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