STM32 ADC sampling voltage fluctuates greatly, please help

stm32f103vct6

STM32 ADC sampling voltage fluctuates greatly, please help [Copy link]

The system power supply is: 24V switching power supply-->DC-DC12v-->7805-->AMS117-3.3 Oscilloscope test AMS1117 ripple peak-to-peak: 180MV A certain pin performs ADC sampling of external voltage, ADC sampling value: (2 types of sampling interrupts and dual ADC) It is found that the sampled data will have a maximum error of 0.1v. What is the cause of this problem and how to solve it? Thank you.

shipeng

Putting aside the fluctuation problem you mentioned, if 24V drops directly to 5V, your 7805 will heat up very much, and the ripple of your 3.3V is close to 0.1V, so what else can I say?

shipeng

What signal does your AD sample? The signal source is very important and you can optimize it accordingly.

stm32f103vct6

shipeng posted on 2018-4-23 12:00 Putting aside the fluctuation problem you mentioned, if 24V is directly reduced to 5V, your 7805 will heat up very much, and in addition, isn't the ripple of your 3.3V close to 0.1V? How can there be more...

I was wrong, there is a DC-DC from 24V to 12V, and then to 7805, the topic has been corrected, thank you

908508455a

1. Separate the analog circuit and digital circuit on the PCB and connect them with copper beads or 0 ohm resistors. 2. Determine whether the signal source has interference by checking the properties of the signal source and add a filter circuit. 3. Optimize the software and add some filter codes.

aptx4860

Obviously, the voltage obtained by the ADC peripheral is not pure. Either optimize the power supply or add a reference source.