In the process of using 48-pin stm32 microcontroller, in order to improve the accuracy and stability of AD acquisition. The VDDA pin needs to be powered independently (the 48-pin microcontroller does not have an independent REF pin, which is connected to the VDDA pin internally). As shown below.
The program runs normally when the stm32 MCU is used in this program, but after the GD32 is replaced, the AD acquisition value is always 0; after searching the GD32 user manual, it is found that the VDDA power supply voltage of the GD32 has special instructions, as shown in the figure below
Therefore, when designing, if the VDDA and VDD of the STM32 share the same power supply, the two MCUs can be PIN to PIN compatible. If they are powered independently, please pay attention to the independent power supply voltage.