Tying SPI inputs together to run several ADCs at once

Forum|Forum|1 year ago
June 11, 2024
1 reply
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Dear Community,

I'm working on STM32H743ZIT6 based project.

Here I want to set up 4 ADCs which have SPI interface.

On developer's forum is said "If all ADCs will be sampled at the same point in time with the same settings, then the SCLK, CS, and SDI can be tied together".

Also there mentioned: "Make sure the digital interface is able to drive all of the ADCs at once".

Is STM32H743ZIT6 able to drive all of the ADCs at once?

According to electrical characteristics:

Digital high input voltage logic level - 0.7V x DVDD (min) / DVDD + 0.3V (max);

Digital low input voltage logic level - -0.3 (min) / 0.2 x DVDD (max).

DVDD = 3.3V

Thanks!

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Best answer by Michal Dudka

You need to route:
SCK from first SPI master to all ADCs and all SPI slaves
MOSI from first SPI master to all ADCs SDI
SDO from ADC1 to MISO of SPI master
SDO from ADC2 to MOSI of first SPI slave
SDO from ADC3 to MOSI of second SPI slave
SDO from ADC4 to MOSI of third SPI slave
CS from STM32 to all ADCs