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M
mohandas98
Associate
April 24, 2025
Question

Interfacing a M7 series STM with a 12-bit parallel ADC for radar application

  • April 24, 2025
  • 2 replies
  • 873 views

I want to use an parallel 12-bit or 14-bit ADC with STM 32 bit MCU. I am guessing the best way is to use DCIM to interface with the ADC. The sampling clock need not be very high (< 2 MHz). But i need continuous samples with no interruptions. Can someone suggest a reference design for this? Is using GPIOs better and using DCIM?

2 replies

MasterT
MasterT
Lead II
April 24, 2025

GPIO on F7 can read about 10 MHz at max, having uCPU 100% load. Can't tell regarding DCIM, unlikely it can operate with 10 psec jitter, those interfaces do "gaps" in data stream for useconds.

 I'd suggest 595 shift registers and feed data to SPI

M
mohandas98Author
Associate
April 25, 2025

Thanks. Can I get more electrical details on the internal ADC such as SNR, SFDR etc. Also, I am assuming in continuous sampling mode, the same channel can be sampled in a loop?

MasterT
MasterT
Lead II
April 25, 2025

You can find adc specification data in the data sheet for specific part number. Here is an example for F767

Yes, one channel sampling is supported, using timer to trigger adc "start conversion" and  dma to transfer results to memory, precision in timing - low jitter is guaranteed w/o uCPU interruption.

Screenshot From 2025-04-25 09-31-50.png

 

LCE
LCE
Principal II
April 29, 2025

Better choose a n ADC with SPI / serial interface.

That will save you a lot of trouble concerning PCB layout and firmware.

Okay, EMI might get worse due to higher clock rates, but you'll probably screw it also with that many parallel data lines anyway...

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