"Jumps" in ADC output of stm32G474RET6 using DMA

[Mshakiba]

I am running the ADC using a timer trigger and DMA to sample a sinusoidal signal.
The captured samples are transmitted to a PC via UART.
However, as shown in the attached image, the ADC output appears to be step-like and does not capture smoothly changing values, even though the input signal is a clean sine wave.
I have checked the external reference voltage, interrupts, and the microcontroller power supply, but the issue still persist

[TDK]

Are you calibrating the ADC on startup? This is mandatory.

Are there appropriate decoupling caps next to the VREF+ pin?

Consider sharing the schematic if you can.

[KnarfB]

The error may be in your DMA code?

Try ADC sampling by polling first for checking analog input signal integrity.

hth

KnarfB

[Andrew Neil]

welcome to the forum.

Please give some more details about your setup;  in particular, your code & schematic - see:

How to write your question to maximize your chances to find a solution

 

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@Mshakiba wrote:

as shown in the attached image, the ADC output appears to be step-like and does not capture smoothly changing values,

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The images show that it does correctly capture the smoothly changing values most of the time - there is just a regular "glich" at a certain point in the waveform.

Does that glitch correspond to where your DMA completes?

Or where your UART transmission occurs?

Or something else that happens regularly in your system?

 

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@Mshakiba wrote:

I am running the ADC using a timer trigger and DMA to sample a sinusoidal signal.

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As @KnarfB said, have you tried it without DMA ?

Have you tried it with steady voltages - to see if it's something to do with that particular voltage range (rather than time-related) ?

 

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@Mshakiba wrote:

I have checked the external reference voltage, interrupts, and the microcontroller power supply,

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Have you checked the  actual input voltage at the STM32 pin ?