ADC Conversion time and Sampling time

Question

I have an stm32f407g.In the reference manual (in the ADC section) I found several terms I am afraid I have confused between them.I would like to explain my reasoning with an example and get your feedback if I said something wrong. -------------------------------------------------EXAMPLE (points are in order!)---------------------------------------------------------------Suppose I need to sample a signal and I need a Tsample = 166.6 usI need to tell the ADC to sample with that Tsample, however, I need to convert it to cycles:With some approximation I find 480 cycles --> Tsample = 192us (a little different from 166us but it's okay)EDIT: I have to take into account that the datasheet says that Tconv = Tsample + 12 cycles          so actually ADC takes Tconv = 480 + 12 cycles = 492 cycles = 196.8us .. not 192us                              1a) Are these calculations correct? How long does it take the ADC to convert each sample?It depends on the resolution, right?If I use 12 bits, the ADC will need 12 cycles + 3 cycles = 15 cycles ... which converted to seconds are:15 * 1 cycle duration = 15 * 1/(PCLK/Perscaler) = 15 * 1/(10MHz/4) = 5us.2a) Are these calculations correct?2b) Does this mean that every Tsample = 192us the ADC read a sample and takes 5us to convert it?---------------------------------------------------------------------------------------------------------------------------------------------------------- I hope I have been clear.

Tinnagit · Accepted Answer

may I got what you want about 166us sampling time.
Do you want to make ADC sampling 6Ksps?

if I have correct understanding, it's not about Tsampling and Tconvesion.
you just need ADC trigger every 166.6us so you just need set some timer to trigger ADC every 166.6us but your ADC need to have Tsampling+Tconversion less than 166.6us every much because it also need space time to process another thing while processing.

which ADC had support timer trigger already.

AScha.3 · Answer

steht wunderbar im rm :so with this example settings adc converts in 0,5us .this kind of adc are capacitive SAR converters , see:https://www.analog.com/en/technical-articles/successive-approximation-registers-sar-and-flash-adcs.htmlhttps://www.ti.com.cn/cn/lit/an/slyt176/slyt176.pdf   so: sampling time is first part of conversion, where the input cap C is connected with the input pin and charges to the voltage at this pin. then comes the fixed 12 cycles ...together this is the total conversion time. ok ? first question is : what conversion rate is needed?- at seldom time 1 x -> start adc by software- at very high rate : set adc to continuous mode and adjust speed by setting its clock and sampling time (here 2MHz rate)- at desired medium frequency , ie 10kHz rate : set a timer to generate this 10k and start adc by trigger from this timer.

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