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deckhard
deckhard
Associate III
October 1, 2020
Question

STM32H743 ADC Conversion/Sampling time

  • October 1, 2020
  • 5 replies
  • 1163 views

Hi,

I wonder if the STM32H743 can sample and convert 1 ADC sample in 10 nanoseconds?

According to the specs the ADC speed (sample + convert) at 14bit resolution with 50MHz ADC clock , one sample will take 200 nanoseconds.

I have no problem lowering the resolution to 8bit.

How much time will it take, considering the same ADC clock speed?

This topic has been closed for replies.

5 replies

TDK
TDK
October 1, 2020

10ns corresponds to a frequency of 100 MHz. The ADC clock is 50MHz max. So no, it can't sample and convert in under one ADC clock.

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deckhard
deckhardAuthor
Associate III
October 1, 2020

Do you know of any other ST device that could achieve that?

BTW how do you work out the math?

Thanks!

TDK
TDK
October 1, 2020

> Do you know of any other ST device that could achieve that?

100 Msps is incredibly fast. You're going to need a specialized ADC chip and an FPGA to handle the data. It's not something you're going to find in a microcontroller.

> BTW how do you work out the math?

1 / (10 ns) = 100MHz

Not sure how else to explain that.

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deckhard
deckhardAuthor
Associate III
October 5, 2020

Is it possible to use the STM32H7 gpio pins as parallel bit bus for this propose?

For example is I connect 8 gpio pins (+clock) (for 8 bit resolution) to an external A2D, would it be possible to reach the time of 10 nanoseconds per sample?

deckhard
deckhardAuthor
Associate III
October 2, 2020

Right so 50Mhz would correspond to 20 nanoseconds. So why does the specification indicates it takes 200 nanoseconds? Because each sample takes 10 clock cycles?

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