Schematic for Fun Turquoise Holodeck: Battery-isolated 16-channel...

Dual MCU Design Explanation

bunny5161

why their are two MCU ?

7 days

flux

1:12

General

Project

Knowledge Base

Verifying MCU roles.

Ensuring accuracy in component details.

Explaining the MCU roles.

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Using Knowledge Base Tool.

Issuing knowledge queries.

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

7 days

Ready.

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

Electrical Rule Checks

Duplicate Designators

Reports components with identical designators.

No-Connect Violation

Reports no-connect pins that are connected.

Missing Power • 5

	Component
	STM32F405RGT6 U3
	ISO1I811TXUMA1 U4
	ADS1299IPAGR U1
	SW6124 U7
	ADS1299IPAGR U2

Single Pin Nets

Reports nets that have only one pin connected.

Missing Designator

Reports components without a designator.

Design Rule Checks

Overlapping Copper • 49

Des	Net	Des	Net
R6:P1	AS212-986_A	U2:NC_2	None
R6:P1	AS212-986_A	U2:VCAP1	None
R8:P1	AS212-988_A	U2:VCAP2	None
R9:P1	AS212-989_A	U2:AVDD_3	GND
R9:P1	AS212-989_A	C24:P2	ISOLATED_GND
R9:P1	AS212-989_A	U2:VREFP	None
X1:out	CLK	C49:P2	GND
X1:out	CLK	C49:P1	None
C7:P1	GND	C10:P2	None
C11:P1	GND	U2:NC_2	None
C11:P1	GND	U2:VCAP2	None
C14:P1	GND	C38:P1	R10_C38
C14:P1	GND	C38:P2	U2_IN7P
C24:P1	GND	C10:P2	None
U2:IN1N	IN1N_U2	J5:～RESET～	None
U2:IN1N	IN1N_U2	J5:GNDDetect	None
U2:IN2N	IN2N_U2	J5:～RESET～	None
U2:IN3N	IN3N_U2	J5:NC	None
U2:IN3N	IN3N_U2	J5:NC/TDI	None
C24:P2	ISOLATED_GND	U2:AVDD_2	GND
C24:P2	ISOLATED_GND	U2:AVDD_3	GND
C24:P2	ISOLATED_GND	U2:AVSS_2	None
C24:P2	ISOLATED_GND	U2:NC_1	None
C24:P2	ISOLATED_GND	U2:VCAP4	None
C24:P2	ISOLATED_GND	U2:VREFN	None
C24:P2	ISOLATED_GND	U2:VREFP	None
R6:P2	R6_C34	R8:P1	AS212-988_A
R6:P2	R6_C34	U2:RESV1	None
R6:P2	R6_C34	U2:VCAP2	None
R8:P2	R8_C36	U2:AVSS_3	None
R9:P2	R9_C37	C24:P2	ISOLATED_GND
R9:P2	R9_C37	U2:VCAP4	None
R9:P2	R9_C37	U2:VREFN	None
C44:P1	R16_C44	R19:P2	None
U2:IN1P	U2_IN7P	J5:～RESET～	None
U2:IN1P	U2_IN7P	J5:GNDDetect	None
U2:IN2P	U2_IN7P	J5:～RESET～	None
U2:IN2P	U2_IN7P	J5:GNDDetect	None
U2:IN4P	U2_IN7P	J5:NC	None
U2:IN4P	U2_IN7P	J5:NC/TDI	None
U2:IN5P	U2_IN7P	J5:NC	None
U2:IN5P	U2_IN7P	J5:NC/TDI	None
U2:IN6P	U2_IN7P	J5:SWO/TDO	None
U2:IN7P	U2_IN7P	J5:GND	None
U2:IN7P	U2_IN7P	J5:SWO/TDO	None
C7:P2	None	C24:P1	GND
C14:P2	None	C36:P1	R8_C36
C14:P2	None	C36:P2	U2_IN7P
C48:P1	None	U2:DVDD_2	GND

Invalid Layer

Reports nodes that are assigned to a layer that doesn't exist in the layout stackup.

Component Overrides

Reports components that have been modified using the "!important" flag.

Airwires

Reports missing routed traces between pads in a net.

Layers with Multiple Fills

Reports layers that have multiple copper fills of different nets. Make sure the Connected Layers rule value of nets with fills is valid.

Floating Copper

Detect any via, trace or copper fill island that is not connected to any net.

Protected Intrusions

Reports intrusions from objects of other nets into polygons or fills that have the Protected layout rule applied.

Missing Footprints

Reports components that need a footprint but don't have one.

Manufacturing

Manufacturer Part Number • 74

	Designator	MPN
	C1	None
	C2	None
	C3	None
	C4	None
	C5	None
	C6	None
	C7	None
	C8	None
	C9	None
	C10	None
	C11	None
	C12	None
	C13	None
	C14	None
	C15	None
	C16	None
	C17	None
	C18	None
	C19	None
	C20	None
	C21	None
	C22	None
	C23	None
	C24	None
	C25	None
	C26	None
	C27	None
	C28	None
	C29	None
	C30	None
	C31	None
	C32	None
	C33	None
	C34	None
	C35	None
	C36	None
	C37	None
	C38	None
	C39	None
	C40	None
	C41	None
	C42	None
	C43	None
	C44	None
	C45	None
	C46	None
	C47	None
	C48	None
	C49	None
	J1	None
	J2	None
	J3	None
	J5	None
	R1	None
	R2	None
	R3	None
	R4	None
	R5	None
	R6	None
	R7	None
	R8	None
	R9	None
	R10	None
	R11	None
	R12	None
	R13	None
	R14	None
	R15	None
	R16	None
	R17	None
	R18	None
	R19	None
	R20	None
	R21	None

Parts Available

Beta

Checks that all components are available from distributors.

System Checks

Auto-Layout

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Reports issues with Auto-Layout if Flux cannot route something or must ignore a configuration.

Passive Components

Resistor Power Rating

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Checks that the power traveling across a given resistor is under its rating with 50% headroom.

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Pull Up/Pull Down Presence

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Checks that IC pins that require pull up or pull down resistors have them.

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Capacitor Voltage Rating

Beta

Checks that capacitors have appropriate voltage ratings to prevent overheating and ensure reliable circuit operation.

Ground
A common return path for electric current. Commonly known as ground.
jharwinbarrozo
20.5M
Net Portal
Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
jharwinbarrozo
43.0M
Power Net Portal
Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #power
jharwinbarrozo
11.4M
Generic Resistor
A generic fixed resistor for rapid developing circuit topology. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0Ω 10Ω 100Ω 1.0kΩ 10kΩ 100kΩ 1.0MΩ 1.1Ω 11Ω 110Ω 1.1kΩ 11kΩ 110kΩ 1.1MΩ 1.2Ω 12Ω 120Ω 1.2kΩ 12kΩ 120kΩ 1.2MΩ 1.3Ω 13Ω 130Ω 1.3kΩ 13kΩ 130kΩ 1.3MΩ 1.5Ω 15Ω 150Ω 1.5kΩ 15kΩ 150kΩ 1.5MΩ 1.6Ω 16Ω 160Ω 1.6kΩ 16kΩ 160kΩ 1.6MΩ 1.8Ω 18Ω 180Ω 1.8KΩ 18kΩ 180kΩ 1.8MΩ 2.0Ω 20Ω 200Ω 2.0kΩ 20kΩ 200kΩ 2.0MΩ 2.2Ω 22Ω 220Ω 2.2kΩ 22kΩ 220kΩ 2.2MΩ 2.4Ω 24Ω 240Ω 2.4kΩ 24kΩ 240kΩ 2.4MΩ 2.7Ω 27Ω 270Ω 2.7kΩ 27kΩ 270kΩ 2.7MΩ 3.0Ω 30Ω 300Ω 3.0KΩ 30KΩ 300KΩ 3.0MΩ 3.3Ω 33Ω 330Ω 3.3kΩ 33kΩ 330kΩ 3.3MΩ 3.6Ω 36Ω 360Ω 3.6kΩ 36kΩ 360kΩ 3.6MΩ 3.9Ω 39Ω 390Ω 3.9kΩ 39kΩ 390kΩ 3.9MΩ 4.3Ω 43Ω 430Ω 4.3kΩ 43KΩ 430KΩ 4.3MΩ 4.7Ω 47Ω 470Ω 4.7kΩ 47kΩ 470kΩ 4.7MΩ 5.1Ω 51Ω 510Ω 5.1kΩ 51kΩ 510kΩ 5.1MΩ 5.6Ω 56Ω 560Ω 5.6kΩ 56kΩ 560kΩ 5.6MΩ 6.2Ω 62Ω 620Ω 6.2kΩ 62KΩ 620KΩ 6.2MΩ 6.8Ω 68Ω 680Ω 6.8kΩ 68kΩ 680kΩ 6.8MΩ 7.5Ω 75Ω 750Ω 7.5kΩ 75kΩ 750kΩ 7.5MΩ 8.2Ω 82Ω 820Ω 8.2kΩ 82kΩ 820kΩ 8.2MΩ 9.1Ω 91Ω 910Ω 9.1kΩ 91kΩ 910kΩ 9.1MΩ #generics #CommonPartsLibrary
jharwinbarrozo
1.5M
Generic Capacitor
A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF 10pF 100pF 1000pF 0.01uF 0.1uF 1.0uF 10uF 100uF 1000uF 10,000uF 1.1pF 11pF 110pF 1100pF 1.2pF 12pF 120pF 1200pF 1.3pF 13pF 130pF 1300pF 1.5pF 15pF 150pF 1500pF 0.015uF 0.15uF 1.5uF 15uF 150uF 1500uF 1.6pF 16pF 160pF 1600pF 1.8pF 18pF 180pF 1800pF 2.0pF 20pF 200pF 2000pF 2.2pF 22pF 20pF 2200pF 0.022uF 0.22uF 2.2uF 22uF 220uF 2200uF 2.4pF 24pF 240pF 2400pF 2.7pF 27pF 270pF 2700pF 3.0pF 30pF 300pF 3000pF 3.3pF 33pF 330pF 3300pF 0.033uF 0.33uF 3.3uF 33uF 330uF 3300uF 3.6pF 36pF 360pF 3600pF 3.9pF 39pF 390pF 3900pF 4.3pF 43pF 430pF 4300pF 4.7pF 47pF 470pF 4700pF 0.047uF 0.47uF 4.7uF 47uF 470uF 4700uF 5.1pF 51pF 510pF 5100pF 5.6pF 56pF 560pF 5600pF 6.2pF 62pF 620pF 6200pF 6.8pF 68pF 680pF 6800pF 0.068uF 0.68uF 6.8uF 68uF 680uF 6800uF 7.5pF 75pF 750pF 7500pF 8.2pF 82pF 820pF 8200pF 9.1pF 91pF 910pF 9100pF #generics #CommonPartsLibrary
jharwinbarrozo
1.5M
Generic Inductor
A generic fixed inductor for rapid developing circuit topology. *You can now change the footprint and 3D model at the top level anytime you want. This is the power of #generics
jharwinbarrozo
15.2k
Terminal
An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
natarius
RMCF0805JT47K0
47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlink
jharwinbarrozo
1.2M
875105359001
10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
jharwinbarrozo
1.2M
CTL1206FYW1T
Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
jharwinbarrozo
1.1M

Inspect

Fun Turquoise Holodeck

Controls

Properties

Project Title

J3 Pin Mapping

System Architecture

CH Nets Review

Capacitor Voltage ERC Status

Availability & Pricing

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

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