Analog value in once channel causing other channels to change

[NNada.1]

Hello All,

  I have STM32F401RE Nucleo board, I have connected the controller as below.

However when I hit one Piezo all adc channels are getting triggered.

I am continously polling every channels to get the ADC values.

1. Is this an hardware issue in STM Controller?

2. Please find my code attached.

 

[TDK]

Piezos will stimulate each other. Are these nearby each other? Your signals are very weakly tied to ground, but I would expect to see some response. Based on the curve you show, it appears these channels are being overstimulated--with a voltage above VREF+, which is not good. Possibly below VREF-/VSS as well.

> sConfig.SamplingTime = ADC_SAMPLETIME_3CYCLES;

Use a larger sampling time. Other things you can do to improve accuracy are included here:

How to optimize the ADC accuracy in the STM32 MCUs - Application note

[NNada.1]

Hii,

 Thanks for the response.

1.However, could you please elaborate on peizo stimulate each other?

2.I have shorted all the ground of peizo and connected to the Nucleo board ground. Is there anything else I should do?

3.Peizo are being overstimulated, even if the peizo values are below 3.3 All the remaing cha nels follow a similar trend.

 

Thank you