24 bit adc resolution with dual mode

[Yandas]

Hello everyone,
I have a stm32h573. I want to get 24 bit resolution. There were those who said I could do it in dual mode. Can I get 24 bit adc resolution using dual mode? There is a 36 bit CDR register. But I really want to know if it will give 24 bit resolution. Can you help?

Thank you.

[AScha.3]

Hi,

the ADC has 12bit ; real effective resolution is about:

 

So you might get 12...14bit data with oversampling/averaging , but 24bit - never.

You could get a 24bit "number" by summing many conversions, but this is not a real 24bit resolution.

Read the AN5354  about ADC in your chip.

And with dual mode you just get two 12bit results - thats all.

 

[Yandas]

Hello @AScha.3 ,
I was going to correct it to 12, not 16, but you did. I was told that I could do 12 bit adc and dual regular simultaneous mode. So why does the Common Data Register carry a 36 bit value if we cannot get a 24 bit value? Why is this necessary?

[mƎALLEm]

Hello,

If there was a such feature it were described in the introduction or main feature sections of 26 Analog-to-digital converters (ADC1/2):

26.1 Introduction / 26.2 ADC main features

Nothing tells in these section that in Dual mode you can configure the two ADCs to get 24-bit resolution!

[Yandas]

Hi @mƎALLEm,
Thank you for your answers. We agreed that I can't get 24 bit resolution. I just don't understand why we need to store two adc data in a 32 bit data register in dual mode. Thanks for your help.

[mƎALLEm]

Because in dual mode (example: regular simultaneous mode) we want to get the converted values of the two ADCs at the same time and read them at once in a 32-bit value.

PS: ADC_CDR register is a 32-bit and not 36-bit

[Yandas]

Hi @mƎALLEm ,
I wrote the 36 bit part by mistake, I corrected it in my next answer. Thank you. I understand very well.