STM32H743 ADC3 Acquisition voltage accuracy

[hanqingze]

Now I want to use ADC3 to collect the voltage of single-ended signals. I used IN1 channel to collect the reference voltage source of 1.5V and the internal channel to collect the internal reference voltage source of the chip respectively. The test results are as follows。The code value returned and the corresponding voltage size are shown in the figure below。

 

It can be found that the error of code is relatively large, because the bits of ADC can not reach 16 bits or what other reasons? Please advise

[TDK]

Increase the sampling time to max for the best accuracy, and average many readings for even better accuracy for DC signals.

Is this a custom board? If so post the schematic.

General tips for improving ADC accuracy around found within here:

cd00211314-how-to-get-the-best-adc-accuracy-in-stm32-microcontrollers-stmicroelectronics.pdf

 

[hanqingze]

原理图就是一块很简单的开发板

[TDK]

Small and branching ground traces are not ideal. The VDDA pin should have a larger capacitor near it to prevent voltage drops. The datasheet says 1 uF in addition to the 0.1 uF. That will certainly help, as would using a ferrite bead before the VDDA/VREF+ supply.

 

Lots of other tips in that application note.

You will never get the full 16 bits of precision with no noise, but you can get 12-14 or so, depending on settings.

[hanqingze]

我需要至少0.1s返回一个平均值数据，我尝试在0.1s多让DAC转换几次取平均值，但是我对此抱有悲观态度，因为上面的误差如此之大感觉很难用取均值方法改善，后续阅读完PDF我再与您交流