Dear support team,
I use the ADC0 of the S32K144 to measure voltage (0 to 36V).
The ADC channel is configured to measure continuously at a sample rate of 5µs. DMA transfer are triggered to transfer 32 ADC measurement into the buffer. Then, filtering and conversions are performed.
I have two problems:
- The raw values into the buffer vary a lot (constant noise of ~ 15 digits)
- The final voltage measured (filtered) is not accurate enough:
This picture shows the absolute error in function of the input voltage. Each point on the graph is a mean of 10 measurements (on these 10 measurement, the noise on measured values never exceed 5mV). As you can see, the error is very random (e.g. +40mV at 25.0V, -30mV at 26.0V).
I tried to enable the ADC self calibration, and the results are even worse.
Do you have any idea on how to improve my measurement accuracy ? (measurement rate ? reference voltage ? analog input capacitor ?)
I hope you can help,
Thank you very much.