Dual MCU Design Explanation

why their are two MCU ?

Thought for 1 min 12 sec

Short answer: we split duties between two MCUs to keep the EEG acquisition deterministic and quiet, while offloading wireless and app features.

U3: real-time host for the dual ADS1299s, clocked SPI/DMA capture, precise timing, and local tasks like storage. This keeps jitter low and digital noise away from the sensitive analog front end.
U8: handles wireless/connectivity and higher-level tasks so the acquisition MCU doesn’t get interrupted by networking stacks.

Benefits:

Deterministic sampling and lower coupling into the analog front end (prioritize ground separation over supply separation to reduce noise return-path coupling).
Cleaner isolation boundary: the noisy RF/stack side is kept off the patient-side analog domain.
Robustness: connectivity issues don’t stall or jitter the data-acquisition loop.

If you’d prefer a single-MCU approach, we can discuss the trade-offs (more jitter/interrupt load near the AFE, tighter noise controls, and isolation constraints).

Prefer single MCU

Clarify MCU connection

Noise isolation guidance

Sampling requirements

Power/EMI concern

U5 -Vout - C24 P2

U5 +Vin - C24 P1

U6 IN - C26 P1

C26

Capacitance

10 uF

U6 OUT - C27 P1

U5 +Vout - C25 P1

C24

Capacitance

10 uF

C25

Capacitance

10 uF

C27

Capacitance

10 uF

Reviews

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Project Name

Description

Battery-isolated 16-channel medical-grade EEG front end using dual ADS1299 analog front-ends and an STM32F405 host with integrated WiFi and microSD (SDIO), featuring corrected isolation, and robust low-jitter clock distribution for dual ADS1299 #WiFi #microSD #Isolation #Clocking #ADS1299 #STM32

Properties

Project Title

Domain

J3 Pin Mapping

System Architecture

Diagram

CH Nets Review

Capacito…C Status

Pricing & Availability

Distributor	Qty 1
Arrow	$100.45–$190.86
Digi-Key	$120.93–$122.68
LCSC	$81.79–$101.52
Mouser	$194.58
TME	$23.96
Verical	$93.28–$200.73

Controls

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