stm32f429-disc1

[harry123]

Hello

Using internal adc for sampling the Analog signal of voltage 300mV.

The output of ADC on plotting has noise. On increasing the voltage the the waveform gets clearer. What could be the reason and how to overcome it?

[STTwo-32]

Hello @harry123 

According to the errata 2.2.8 of the  ES0206, An internal noise generated on VDD supplies and propagated internally may impact the ADC accuracy. This noise is always present whatever the power mode of the MCU (Run or Sleep).

As a workaround, you should Use the following sequence to adapt the accuracy level to the application requirements:

• 1. Configure the flash memory ART with prefetch OFF and data + instruction cache ON.
• 2. Use averaging and filtering algorithms on ADC output codes.

For more details, I suggest you to use the AN4073 and AN2834 that help you on how to optimize the ADC accuracy.

Best Regards.

STTwo-32 

[harry123]

• 1. Configure the flash memory ART with prefetch OFF and data + instruction cache ON.can you please elaborate on how to do it?

[TDK · Accepted solution]

Those options are in the RCC tab in CubeMX.

Note that sampling time will have the largest effect on ADC accuracy and that some amount of noise at 12-bit resolution is unavoidable.

[harry123]

Thank you 

As the is more noise it is getting difficult for me to detect zero-crossing is there any way that I can do?