Precise ADC for STM32F4

[ameer]

Posted on September 08, 2015 at 19:42

Hi,

I want to have precise ADC readings on stm32f4 for my project work but it always give me about 1% of error. For example if i take 0 V reading by grounding 12bit ADC it gives readings in between 0-15 (out of 4095 steps).Also attached is the wave generated from DAC and i take its reading from ADC and ploted in QT through Virtual Com Port. as you can see there are some fluctuation in values even when voltage is constant.Is there any way to precise the adc values just like in STM32F3 we have ADC calibration but it is absent in STM32F4. Or is there any channel which is more accurate than others in F4.Many Thanks.Hamza. #adc #stm32f4

[waclawek.jan]

Posted on September 08, 2015 at 20:53

Yes, the STM32F4 ADC is disappointingly noisy. You might want to review AN4073, but don't expect miracles. Analog circuitry madufactured on digital-optimized process has its limitations, especially if integrated with a relatively large digital circuit onto a single piece of silicon. You might want to consider an external ADC if you desire better accuracy and/or lower noise.

JW

[ameer]

Posted on September 08, 2015 at 21:27

Thanks for your reply. Its really disappointing to hear this. May be i will try some software filter because i can not afford to ship external ADC chip as it takes more than a month to reach a product in my country and i have got to submit my project. Or do you have any other better solution ?

[waclawek.jan]

Posted on September 10, 2015 at 14:17

I have nothing better. You can also try to decouple the analog supply from digital using RLC filters, and you can try to reduce digital noise by reducing/stopping core and avoiding switching external loads during the conversion. None of this will have dramatic effect, probably, but maybe together might yield the desired result.

JW