STM32F373 SDADC Analog input range

[Nandish Jasani]

Hi,

I have 50Hz sinewave with 660mVp-pk, should i connect this to SDADC analog input? It can measure negative cycle of the sinewave? i.e. If i configure SDADC as single ended zero reference mode then it can measure negative cycle of the sinewave?

Nandish

[waclawek.jan]

> If i configure SDADC as single ended zero reference mode then it can measure negative cycle of the sinewave?

No. You have to observe the voltage limits given in datasheet.

JW

[Ozone]

JW is correct, you cannot measure negative voltages with on-chip means.

You need a dual-supplied opamp to shift the voltage to 0...1320mV - which can amplify the signal by at least factor 2 to make better use of the ADC range.

[Uwe Bonnes]

You can bias the ADC input at VREF/2 and capacitive couple the AC input. However as a tip, reconsider the use of the F353 SDADC. Without calibrating each channel, gain is off about 1 % . Calbration must happen with a MUX providing 0.5 ... 0.95 VREF, as VREF will lead to overflow.