CAN Transceiver Connections Explained

flux

1:43

Evaluating user's PCB inquiry.

Identifying intents.

Gathering layout information.

Providing guidance on antenna keepout.

Accessing knowledge base.

Looking for "antenna keep-out area keepout pcb layout guidelines no copper under antenna" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Looking for "recommended clearance distance around the onboard antenna minimum distance to ground plane or copper" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Looking for "ESP32-S3-WROOM-1 hardware design guidelines antenna area multilayer copper restrictions vias components under antenna" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Looking for "package land pattern antenna area dimensions mechanical drawing antenna end length and width" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Looking for "statement about do not place copper traces or ground under antenna and suggested 15 mm clearance" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Searching web for: "ESP32-S3-WROOM-1 hardware design guidelines antenna keepout no copper under antenna datasheet PDF"

Found 1 results.

Analyzing the PCB layout.

Proceeding with queries for U4.

Short answer: Yes—any copper or parts on any layer under the ESP32 module’s antenna will degrade RF. That includes bottom-layer CAN traces and the CAN transceiver placed under the antenna projection.
What the docs require (ESP32-S3 HW Design Guidelines / module datasheet):
  • Keep at least 15 mm clearance around the antenna area.
  • No copper, no traces, no vias, no components in that area on any layer.
  • Prefer a board cutout under the antenna if possible.
Your PCB right now:
  • U4 is at the origin with the antenna end defined in the footprint; I see 57cfc4e2-133e-4f3e-bc11-a59269bbb67b/d9f9a055-e850-4ab5-ac5e-f936252b3a99 routed on the Bottom in the 9.7–13.4 mm X region near U4, which falls under the module’s footprint area and is very likely within the antenna projection.
  • U2 is placed at about 9.05 mm, -3.94 mm, i.e., underneath/adjacent to the module; that also risks being under the antenna zone.
Recommendations (pick one or combine):
  • Move U2 and reroute CAN so no copper exists under the antenna projection of U4.
  • Add an all-layer keepout matching the antenna projection plus a 15 mm margin; forbid polygons, traces, and vias inside it.
  • If space is truly constrained, add a board cutout under the antenna region; even then, keep parts away from the 15 mm zone.
  • If you must violate this for an early proto, expect reduced range/detuning; verify with RSSI/range testing.
If you want, I can mark the antenna projection zone in the layout for you and list any nets crossing it so you can reroute around it.
123 days
iblamematthew

iblamematthew

ok and can the antenna be sticking off the pcb? like pads on pcb and antenna no?
123 days

flux

1:23

Interpreting antenna placement.

Gathering design guidelines.

Querying for antenna guidelines.

Accessing knowledge base.

Looking for "antenna keepout area no copper traces components recommendation" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Looking for "placement recommendations module antenna near board edge overhang allowed" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Looking for "minimum clearance distance around antenna mm" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Looking for "mechanical drawing antenna area outline land pattern notes" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Looking for "hardware design guidelines antenna PCB cutout under antenna" in esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf

Searching web for: "ESP32-S3-WROOM-1 antenna keepout board edge placement overhang hardware design guidelines"

Found 1 results.

Setting formatting guidelines.

Yes—this is actually the preferred placement. For the ESP32-S3 module U4, Espressif recommends putting the antenna portion outside the main PCB outline (overhanging the board edge). That minimizes detuning from the baseboard.
Key rules to follow
  • Overhang OK (recommended): Keep the castellated pads fully on the PCB, and let only the antenna end project past the edge.
  • All-layer keepout: No copper, traces, vias, or components under the antenna area on any layer. If the antenna cannot overhang, maintain at least 15 mm clearance around the antenna region on all layers.
  • Enclosure clearance: Keep metal (shields, screws, battery cans, cables) out of that antenna zone. Test range in the final enclosure.
  • Assembly/mechanical: Ensure the module is well supported during reflow (panel rails or nearby board material) so the overhanging antenna isn’t stressed. Do not route board-edge fiducials or breakaways through the antenna keepout.
If you want, I can mark the antenna keepout in your layout around U4 and flag any traces/vias that cross it so you can reroute.
Confirm overhang distance
Ask about board cutout
Enclosure constraint
Keepout setup
Check current placement
123 days
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LED1
GND
C9 P1 - R14 P2
JTAG1 Pin_9 - GND GND
JTAG1 Pin_9 - GND GND
U2 CANH - R14 P1
5V
JTAG1 Pin_9 - GND GND
3V3
JTAG1 Pin_9 - GND GND
5V
3V3
3V3
U2 CANL - R15 P2
JTAG1 Pin_9 - GND GND
5V
C9 P1 - R14 P2
C5
Capacitance
22uF
LED1
R14
Resistance
500 Ω
R15
Resistance
500 Ω
C12
Capacitance
Capacitance
U1
C4
Capacitance
22uF
C10
Capacitance
Capacitance
C11
Capacitance
Capacitance
C9
Capacitance
Capacitance
  • Ground
    Ground
    A common return path for electric current. Commonly known as ground.
    jharwinbarrozo
    20.5M
  • Net Portal
    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
    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
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  • Generic Resistor
    Generic Resistor
    A generic fixed resistor ideal for rapid circuit topology development. Its footprint automatically adapts based on the selected package case code—supporting 0402, 0603, 0805, 1203, and many other standard SMD packages, as well as axial horizontal and vertical configurations. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0 ohm, 10 ohm, 100 ohm, 1.0k ohm, 10k ohm, 100k ohm, 1.0M ohm 1.1 ohm, 11 ohm, 110 ohm, 1.1k ohm, 11k ohm, 110k ohm, 1.1M ohm 1.2 ohm, 12 ohm, 120 ohm, 1.2k ohm, 12k ohm, 120k ohm, 1.2M ohm 1.3 ohm, 13 ohm, 130 ohm, 1.3k ohm, 13k ohm, 130k ohm, 1.3M ohm 1.5 ohm, 15 ohm, 150 ohm, 1.5k ohm, 15k ohm, 150k ohm, 1.5M ohm 1.6 ohm, 16 ohm, 160 ohm, 1.6k ohm, 16k ohm, 160k ohm, 1.6M ohm 1.8 ohm, 18 ohm, 180 ohm, 1.8K ohm, 18k ohm, 180k ohm, 1.8M ohm 2.0 ohm, 20 ohm, 200 ohm, 2.0k ohm, 20k ohm, 200k ohm, 2.0M ohm 2.2 ohm, 22 ohm, 220 ohm, 2.2k ohm, 22k ohm, 220k ohm, 2.2M ohm 2.4 ohm, 24 ohm, 240 ohm, 2.4k ohm, 24k ohm, 240k ohm, 2.4M ohm 2.7 ohm, 27 ohm, 270 ohm, 2.7k ohm, 27k ohm, 270k ohm, 2.7M ohm 3.0 ohm, 30 ohm, 300 ohm, 3.0K ohm, 30K ohm, 300K ohm, 3.0M ohm 3.3 ohm, 33 ohm, 330 ohm, 3.3k ohm, 33k ohm, 330k ohm, 3.3M ohm 3.6 ohm, 36 ohm, 360 ohm, 3.6k ohm, 36k ohm, 360k ohm, 3.6M ohm 3.9 ohm, 39 ohm, 390 ohm, 3.9k ohm, 39k ohm, 390k ohm, 3.9M ohm 4.3 ohm, 43 ohm, 430 ohm, 4.3k ohm, 43K ohm, 430K ohm, 4.3M ohm 4.7 ohm, 47 ohm, 470 ohm, 4.7k ohm, 47k ohm, 470k ohm, 4.7M ohm 5.1 ohm, 51 ohm, 510 ohm, 5.1k ohm, 51k ohm, 510k ohm, 5.1M ohm 5.6 ohm, 56 ohm, 560 ohm, 5.6k ohm, 56k ohm, 560k ohm, 5.6M ohm 6.2 ohm, 62 ohm, 620 ohm, 6.2k ohm, 62K ohm, 620K ohm, 6.2M ohm 6.8 ohm, 68 ohm, 680 ohm, 6.8k ohm, 68k ohm, 680k ohm, 6.8M ohm 7.5 ohm, 75 ohm, 750 ohm, 7.5k ohm, 75k ohm, 750k ohm, 7.5M ohm 8.2 ohm, 82 ohm, 820 ohm, 8.2k ohm, 82k ohm, 820k ohm, 8.2M ohm 9.1 ohm, 91 ohm, 910 ohm, 9.1k ohm, 91k ohm, 910k ohm, 9.1M ohm #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Capacitor
    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, 10000uF 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, 220pF, 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
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  • Generic Inductor
    Generic Inductor
    A generic fixed inductor suitable for rapid circuit topology development. The footprint automatically adapts based on the selected package, supporting standard SMD sizes (e.g., 0402, 0603, 0805) as well as well-known inductor packages such as SDR1806, PA4320, SRN6028, and SRR1260. Standard inductor values: 1.0 nH, 10 nH, 100 nH, 1.0 µH, 10 µH, 100 µH, 1.0 mH 1.2 nH, 12 nH, 120 nH, 1.2 µH, 12 µH, 120 µH, 1.2 mH 1.5 nH, 15 nH, 150 nH, 1.5 µH, 15 µH, 150 µH, 1.5 mH 1.8 nH, 18 nH, 180 nH, 1.8 µH, 18 µH, 180 µH, 1.8 mH 2.2 nH, 22 nH, 220 nH, 2.2 µH, 22 µH, 220 µH, 2.2 mH 2.7 nH, 27 nH, 270 nH, 2.7 µH, 27 µH, 270 µH, 2.7 mH 3.3 nH, 33 nH, 330 nH, 3.3 µH, 33 µH, 330 µH, 3.3 mH 3.9 nH, 39 nH, 390 nH, 3.9 µH, 39 µH, 390 µH, 3.9 mH 4.7 nH, 47 nH, 470 nH, 4.7 µH, 47 µH, 470 µH, 4.7 mH 5.6 nH, 56 nH, 560 nH, 5.6 µH, 56 µH, 560 µH, 5.6 mH 6.8 nH, 68 nH, 680 nH, 6.8 µH, 68 µH, 680 µH, 6.8 mH 8.2 nH, 82 nH, 820 nH, 8.2 µH, 82 µH, 820 µH, 8.2 mH #generics #CommonPartsLibrary
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    15.8k
  • Terminal
    Terminal
    An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
    natarius
  • RMCF0805JT47K0
    RMCF0805JT47K0
    General Purpose Thick Film Standard Power and High-Power Chip Resistor 47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film Features: - RMCF – standard power ratings - RMCP – high power ratings - Nickel barrier terminations standard - Power derating from 100% at 70ºC to zero at +155ºC - RoHS compliant, REACH compliant, and halogen free - AEC-Q200 compliant
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  • 875105359001
    875105359001
    10 µF 16 V Aluminum - Polymer Capacitors Radial, Can - SMD 30mOhm 2000 Hrs @ 105°C #commonpartslibrary #capacitor #aluminumpolymer #radialcan
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  • CTL1206FYW1T
    CTL1206FYW1T
    Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric)
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theRevLinkBVR00009 thumbnail
R11:P2 Connected to nRESET Net for Persistent Pull-Up on Reset Line

Properties

Diagram



  
    
  
  
    
  




K

A



VBAT
AEC-Q101 TVS Diode
GND

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