This is one of the simplest FM transmitters that can be built. It does not require any tuning, and transmit frequency is crystal locked to 90MHz. It eliminates frequency drift common to LC-based FM transmitters. This design is best suited for broadcasting voice or music up to a distance of fifty metres depending on the antenna used.

NEO-M9N GPS Breakout with on-board chip antenna is a high quality GPS board with equally impressive configuration options. The NEO-M9N module is a 92-channel u-blox M9 engine GNSS receiver, meaning it can receive signals from the GPS, GLONASS, Galileo, and BeiDou constellations witn ~1.5 meter accuracy. This breakout supports concurrent reception of four GNSS. This maximizes position accuracy in challenging conditions, increasing precision and decreases lock time; and thanks to the onboard rechargeable battery, you'll have backup power enabling the GPS to get a hot lock within seconds! Additionally, this u-blox receiver supports I2C (u-blox calls this Display Data Channel) which made it perfect for the Qwiic compatibility so we don't have to use up our precious UART ports. Utilizing our handy Qwiic system, no soldering is required to connect it to the rest of your system. However, we still have broken out 0.1"-spaced pins in case you prefer to use a breadboard.

SPECIFICATIONS: • Gain: 10dBi @ 2.4/5.8GHz • Impedance: 50Ω • VSWR: <1.5:1 • Connector: SMA Male • PCB: FR-4, 1.6mm • Type: Yagi-Uda • Polarization: Vertical

Ruggedized battery-powered PeakNode 1 LoRa PWAN node with SX1262 LoRa mesh over SPI, LTE Cat-M1/NB-IoT modem, GNSS, LPCNet-capable audio path, USB-C charging and LiFePO4 power management. Targets a 4-layer 90 mm x 60 mm IPC Class 2 layout with 3.3 V main and 1.8 V I/O rails, dual SMA antennas, two RGB status LEDs, three tactile buttons, low-leakage power architecture for sub-10 uA sleep, and defined RF keep-out zones under the LoRa and LTE antenna regions.

High-level recreation of the ThirstIQ Cap wiring diagram using an ESP32-WROOM-32 with AMS1117-3.3 regulated battery input, inline ON/OFF switch, four touch input headers on IO32/IO33/IO25/IO26, shared I2C OLED and RTC on IO21/IO22, UART debug/programming header on TXD0/RXD0, BOOT and RESET pushbuttons on IO0 and EN, buzzer on IO4, common 3V3/GND distribution, and PCB preparation for a 160 mm x 100 mm 4-layer layout. Layout intent includes clean 3.3 V power distribution, local decoupling for regulator and ESP32, accessible external headers/buttons, short clean BOOT/EN traces, shared I2C routing, touch-signal separation from noisy power and buzzer traces, and ESP32 antenna keepout.

Bluetooth RC car controller using ESP32-WROOM-32E, TB6612FNG dual H-bridge, XL4015 5V buck module, DC barrel battery input, dual 2-pin motor screw terminals, 1000uF VM bulk capacitor, 100nF decoupling, 10k EN pull-up, 30 mil power traces, 10 mil signal traces, and ESP32 antenna edge keep-out.

Waterproof ESP32-C6 BLE MTB GPS Computer with NEO-M9N, LiPo Power Management, USB-C, and External SMA Antenna

This is a compact, high-performance RFID antenna solution built on a printed circuit board configurations. It has miniature RF connector (also known as a U.FL or IPX connector) that allows easy connection to an external antenna. It’s especially useful when you want better signal performance or need to position the antenna away from the main board (e.g., in an enclosure or plastic housing).

A PCB for automotive testing, featuring a 24 GHz radar system with an MCU for processing I&Q values. It connects to a frequency analyzer and uses CW and FMCW modes to detect bicyclists in blind spots of parked cars.

Welcome to your new project. Imagine what you can build here.

Welcome to your new project. Imagine what you can build here.

This is an ESP32-C3 reference design based on the manufacturer's recommendations with a uFL SMD antenna and USB C on board #WiFi #ESP32-C3 #IoT #referenceDesign #simple-embedded #espressif #template #reference-design

ESP8684H4 based thermostat module which will control the heater. The module will have 18650 Li-Ion battery cell with 3.7V nominal voltage. The module also has a switch-mode buck NVDC power path which can simultaneously charge the battery and provide power to the system. The system voltage is 3.3V. Input voltage is 5V from USB-C. The system also contains a temperature, humidity and pressure sensor. The Wi-Fi and Bluetooth antenna implemented by PCB tracks.

This is one of the simplest FM transmitters that can be built. It does not require any tuning, and transmit frequency is crystal locked to 90MHz. It eliminates frequency drift common to LC-based FM transmitters. This design is best suited for broadcasting voice or music up to a distance of fifty metres depending on the antenna used.

This is an ESP32-C3 reference design based on the manufacturer's recommendations with a uFL SMD antenna and USB C on board #WiFi #ESP32-C3 #IoT #referenceDesign #simple-embedded #espressif #template #reference-design

RF Module, ESP32-D0WD SoC, Wi-Fi 802.11b/g/n, Bluetooth, BLE, 32-bit, 2.7-3.6V, onboard antenna, SMD

This is an ESP32-C3 reference design based on the manufacturer's recommendations with a uFL SMD antenna and USB C on board #WiFi #ESP32-C3 #IoT #referenceDesign #simple-embedded #espressif #template #reference-design

An automatic satellite/planet tracker. It can precisely point an antenna or telescope to a moving spacecraft or tracking a planetary object.

Wearable EMG acquisition PCB with 8 differential biopotential channels, BLE/USB MCU, USB-C LiPo charging, 3.3V buck regulation, and 2.4GHz chip antenna path.

## PROJECT OVERVIEW Design a compact, battery-powered, IoT-connected plant monitoring PCB sensor node. The board combines WiFi/BLE connectivity, multi-sensor I2C acquisition, LiPo battery management with USB-C charging, and partially weatherproof design for outdoor/planter use. The physical form factor is a FORK (forcina) shape: a wider rectangular head section (~32×30mm) housing all the electronics, and two narrow prongs (~10×45mm each, 8mm gap between them) extending downward to form the capacitive soil moisture electrodes. Reference: the shape resembles a plant stake that is pushed into soil. I trust Flux AI's routing and placement judgment. Please apply your full expertise. The guidance below defines constraints — treat them as requirements, not suggestions. --- ## BOARD SPECIFICATIONS - Layers: 2 (Top + Bottom copper) - Dimensions: Head 32×30mm + two prongs 10×45mm (total board ~32×75mm) - PCB thickness: 1.6mm FR4 - Surface finish: ENIG (Electroless Nickel Immersion Gold) — MANDATORY Reason: the soil prong traces must be gold-plated for corrosion resistance - Min trace width: 0.15mm signal, 0.5mm power - Min clearance: 0.15mm - Soldermask: GREEN on both sides Exception: NO soldermask on the interdigital soil electrode traces on the prongs (the copper must be fully exposed to contact the soil) - Via: min hole 0.3mm, pad 0.6mm - 4× M2.5 mounting holes (2.7mm drill, 5mm annular copper ring) at corners of head section - Conformal coating keep-out zones: SHT40-AD1F-R2 (U8), VEML7700 (U2), soil electrode traces on prongs, USB-C connector J1 --- ## COMPLETE BILL OF MATERIALS ### Active ICs **U1 — ESP32-C3-MINI-1** (Espressif, LCSC C2838502) - Main microcontroller: RISC-V 32-bit 160MHz, 4MB flash, 400KB RAM - WiFi 802.11b/g/n 2.4GHz + BLE 5.0 - Package: SMD module 13.2×16.6×2.4mm, castellated edges - Operating voltage: 3.0–3.6V from VCC rail - I2C: SDA=GPIO8, SCL=GPIO9 - USB: D+=IO19, D-=IO18 - Status outputs: CHG_STATUS=IO2, PG_STATUS=IO3, LOAD_EN=IO4 - CRITICAL placement: antenna area (rightmost ~3mm of module) must hang over board edge OR have copper keepout zone (no copper top or bottom under antenna area). This is mandatory for RF performance. - Add 100nF + 10µF decoupling on 3V3 pin, placed within 1mm of pin **U2 — VEML7700-TT** (Vishay, LCSC C78606) - Ambient light sensor, 0.0036–120,000 lux, I2C address 0x10 - Package: ODFN-6, 2.0×2.0×0.5mm - Operating voltage: 2.5–3.6V - Current: 90µA active, 0.2µA power-down - CRITICAL placement: position at TOP EDGE of head section, centered horizontally. The sensor photodiode window (top of package) must face upward toward the case lid. A transparent PMMA optical window (Ø10mm) in the case will be positioned directly above this IC. Leave 0mm clearance to board edge on that side if possible. The VEML7700 has ±45° field of view, so alignment does not need to be perfect, but centering under the window opening is preferred. - Add 100nF decoupling on VDD, placed within 1mm **U3 — SHT40-AD1B** (Sensirion, LCSC C1550099) — INTERNAL sensor - Temperature + relative humidity sensor, I2C address 0x44 - Package: DFN-4, 1.5×1.5×0.5mm — extremely small, requires careful pad design - Operating voltage: 1.8–3.6V - Current: 3.2µA per measurement (1ms active), 0.1µA sleep - PURPOSE: measures temperature and humidity INSIDE the case (ambient reference) - CRITICAL placement: position in CENTER of head section PCB, far from all heat sources. Minimum 8mm distance from BQ24090 (U6) and ME6211 (LDO1). The SHT40 chip surface IS the sensor — the hygroscopic polymer capacitor is on the top face of the IC. It must NOT be covered by conformal coating. However, for the internal sensor (U3), it can be in a slightly ventilated cavity inside the case to measure internal temperature drift compensation. - Add 100nF decoupling on VDD within 1mm **U8 — SHT40-AD1F-R2** (Sensirion, LCSC C5155469) — EXTERNAL sensor - Same electrical specs as U3 (SHT40 family), I2C address 0x44 - Package: DFN-4 with integrated PTFE filter cap for dust/water protection The filter cap allows vapor to reach the sensor while blocking liquid water - PURPOSE: measures EXTERNAL ambient temperature and humidity (outside the case) - CRITICAL placement: position on the SIDE or BOTTOM EDGE of head section. This sensor must be accessible from outside the case through a ventilated chamber (labyrinth vent structure in case design). It must NOT be covered by conformal coating. The sensor's filter cap must face the vent opening direction. Minimum 10mm distance from BQ24090 and LDO thermal zone. - Connected via TCA9548A channel 1 (see below) — NOT directly on main I2C bus **U4 — FDC1004DGST** (Texas Instruments, LCSC C266239) - 4-channel capacitance-to-digital converter, I2C address 0x50 - Package: WSON-8, 2.0×2.0×0.8mm - Operating voltage: 3.3V - Current: 750µA active, 300nA shutdown - PURPOSE: reads capacitance of interdigital PCB traces immersed in soil. The IC itself is NOT the soil sensor — it measures the capacitance of external electrodes. CIN1 and CIN2 connect to the interdigital copper traces on the prong section. - CRITICAL placement: position at BOTTOM of head section, closest to prong entry point. This minimizes trace length to CIN1/CIN2, reducing parasitic capacitance pickup. Keep CIN1 and CIN2 traces short, wide (0.3mm+), shielded by GND guard rings on both sides of each trace. Route CIN1/CIN2 on the SAME layer (Bottom preferred) as the interdigital electrodes to avoid via parasitic capacitance. - SHLD1 and SHLD2 pins connect to GND (guard shield) - Add 100nF decoupling on VDD within 1mm **U5 — TCA9548A** (Texas Instruments, LCSC C130026) — NEW COMPONENT vs previous schema - 8-channel I2C multiplexer, I2C address 0x70 - Package: SOIC-24 or TSSOP-24, select smallest available footprint - Operating voltage: 1.65–5.5V - PURPOSE: MANDATORY to resolve I2C address conflict between U3 and U8, both of which have fixed address 0x44. Without this IC the two SHT40 sensors will collide on the bus and produce corrupt readings. Channel 0: connects to U3 (SHT40 internal) Channel 1: connects to U8 (SHT40 external) Main I2C bus (from ESP32): connects to TCA9548A upstream SDA/SCL - Add 100nF decoupling on VCC within 1mm - Reset pin (active low): connect to VCC via 10kΩ (always enabled) OR connect to a GPIO for software reset capability **U6 — BQ24090DGQT** (Texas Instruments, LCSC C179663) - Single-cell LiPo/Li-ion battery charger, input 4.5–6.5V, charge voltage 4.2V - Package: DSBGA-9 (wafer-level), extremely small ~1.6×1.6mm - CRITICAL THERMAL: this IC dissipates up to 0.5W during charging. Place a copper thermal pad area ≥1cm² on BOTH layers under the IC. Add minimum 4 thermal vias (0.3mm hole, 0.6mm pad) under thermal exposed pad. Keep this IC at MAXIMUM distance from both SHT40 sensors. Thermal isolation: route at least 10mm of thin trace (~0.2mm) between BQ24090 thermal zone and any temperature-sensitive component. - ISET pin: connect to R3 (1.8kΩ) to set Icharge ≈ 494mA (C/4 for 2000mAh) - PRETERM pin: connect to R2 (5.1kΩ — keep existing value, sets termination threshold) - ISET2 pin: connect per datasheet recommendation (typically VSYS or VBAT) - TS pin: connect to R4 (10kΩ NTC thermistor or static resistor to GND) If using static resistor: 10kΩ to GND disables thermal protection RECOMMENDATION: add NTC 10kΩ B=3950 near battery for thermal protection - CHG# (open drain): connect to LED_RED via 330Ω to VCC, and to U1 IO2 via 10kΩ - PG# (open drain): connect to LED_GREEN via 330Ω to VCC, and to U1 IO3 via 10kΩ - OUT pin: VBAT rail (to battery positive and to LDO input) **LDO1 — ME6211C33M5G-N** (Nanjing Micro One, LCSC C82942) - LDO regulator, Vin 2.0–6.0V → Vout 3.3V fixed - Package: SOT-23-5, 2.9×1.6mm - Quiescent current: 55µA (higher than MCP1700, but adequate) - Dropout: 300mV @ 100mA - CE pin: connect to VCC (always enabled) or to ESP32 GPIO for power gating - THERMAL NOTE: at full system load (~100mA), dissipation = (Vbat-3.3)×0.1 ≈ 40–90mW. Low risk, but keep minimum 5mm from SHT40 sensors. - Vin decoupling: C2 1µF + C1 100nF - Vout decoupling: C3 10µF (electrolytic or ceramic) + additional 100nF ceramic **O1 — SI2301CDS** (Vishay, LCSC C10487) - P-channel MOSFET, Vds=-20V, Id=-3A, Vgs(th)=-0.4V typ - Package: SOT-23, 2.9×1.6mm - PURPOSE: load switch between VBAT and LDO1 input, controlled by ESP32 This allows the ESP32 to cut power to all sensors during deep sleep for maximum battery life (if desired — optional feature) - Gate connection: 10kΩ pull-up resistor from Gate to VBAT (MOSFET OFF by default) + GPIO IO4 from ESP32 drives Gate to GND through 1kΩ series resistor to turn ON IMPORTANT: this was missing from previous schema — gate must NOT float. Series 1kΩ on gate limits gate charge current and protects GPIO. Pull-up 10kΩ to VBAT ensures MOSFET stays OFF during ESP32 boot/reset. - Source: VBAT (battery positive) - Drain: LDO1 VIN ### Connectors and Passive Components **J1 — USBC_C165948** (USB Type-C SMD receptacle, LCSC C165948) - USB-C connector for 5V power input and ESP32 programming - Position: TOP EDGE of head section (accessible when device is in soil) - VBUS pins → BQ24090 IN (via R_protection 1Ω/1A fuse resistor optional) - D+ → ESP32 IO19, D- → ESP32 IO18 - GND → GND plane - All CC pins → GND via 5.1kΩ resistors (CC1: R_CC1 5.1kΩ, CC2: R_CC2 5.1kΩ) These are MANDATORY for USB-C to deliver 5V (tells charger it is a sink device) WITHOUT these resistors the USB-C port will NOT receive power from modern chargers. **U_BAT — LiPo 2000mAh connector** - Use JST PH 2.0mm 2-pin connector (standard LiPo connector) - Position: head section, easily accessible for battery replacement - Polarity protection: the SI2301 load switch also provides polarity protection if wired with Source=Drain correctly (P-FET body diode blocks reverse current) **R1 — 4.7kΩ ±1% 0402** (CHANGED from 5.1kΩ in previous schema) - I2C SDA pull-up: connects VCC to SDA bus - Reason for change: 4.7kΩ is the standard I2C pull-up value per NXP I2C spec. 5.1kΩ causes slower rise times at 400kHz fast-mode, risking data errors. **R2 — 4.7kΩ ±1% 0402** (CHANGED from 5.1kΩ in previous schema) - I2C SCL pull-up: connects VCC to SCL bus **R3 — 1.8kΩ ±1% 0402** - BQ24090 ISET: sets charge current to ~494mA (Ichg = 890/R3) **R4 — 10kΩ 0402** - BQ24090 TS pin bias or NTC resistor (see BQ24090 notes above) **R5, R6 — 5.1kΩ 0402** (NEW — not in previous schema) - USB-C CC1 and CC2 pull-down resistors (MANDATORY for USB-C power delivery) **R7 — 10kΩ 0402** (NEW) - SI2301 Gate pull-up to VBAT **R8 — 1kΩ 0402** (NEW) - SI2301 Gate series resistor from ESP32 GPIO IO4 **R9, R10 — 330Ω 0402** (NEW) - Current limiting for LED_RED and LED_GREEN (status LEDs) **C1 — 100nF 0402 X5R** — LDO Vin decoupling **C2 — 1µF 0402 X5R** — LDO Vin bulk **C3 — 10µF 0805 X5R** — LDO Vout bulk **C4 — 100nF 0402** — ESP32 VCC decoupling **C5–C9 — 100nF 0402** — Per-IC VCC decoupling (one per U2/U3/U4/U5/U8) **C10 — 4.7µF 0402** — BQ24090 IN bypass **C11 — 4.7µF 0402** — BQ24090 OUT bypass **LED1 — Green 0402** — USB power good / charging complete indicator **LED2 — Red 0402** — Charging in progress indicator **BTN1 — 3×3mm SMD tactile switch** (optional, recommended) - Connected between ESP32 EN pin and GND, with 100nF debounce cap - Allows manual reset without USB for field use --- ## ELECTRICAL NETS SUMMARY | Net Name | Description | Connected to | |----------|-------------|--------------| | VBUS_5V | USB-C 5V input | J1 VBUS, BQ24090 IN | | VBAT | Battery voltage 3.2–4.2V | U_BAT+, BQ24090 OUT, O1 Source | | VCC | Regulated 3.3V | LDO1 OUT, all IC VDD/VCC pins | | GND | Common ground | All GND pins, copper pour both layers | | SDA | I2C data (main bus) | ESP32 IO8, TCA9548A SDA_A, VEML7700 SDA, FDC1004 SDA, R1 pull-up | | SCL | I2C clock (main bus) | ESP32 IO9, TCA9548A SCL_A, VEML7700 SCL, FDC1004 SCL, R2 pull-up | | SDA_CH0 | I2C mux channel 0 | TCA9548A SD0, SHT40-internal SDA | | SCL_CH0 | I2C mux channel 0 | TCA9548A SC0, SHT40-internal SCL | | SDA_CH1 | I2C mux channel 1 | TCA9548A SD1, SHT40-external SDA | | SCL_CH1 | I2C mux channel 1 | TCA9548A SC1, SHT40-external SCL | | SOIL_A | Soil electrode set A | FDC1004 CIN1, interdigital traces prong (even fingers) | | SOIL_B | Soil electrode set B | FDC1004 CIN2, interdigital traces prong (odd fingers) | | USB_DP | USB D+ | J1 D+, ESP32 IO19 | | USB_DM | USB D- | J1 D-, ESP32 IO18 | | CHG_STATUS | Charger status | BQ24090 CHG#, LED_RED, ESP32 IO2 | | PG_STATUS | Power good | BQ24090 PG#, LED_GREEN, ESP32 IO3 | | LOAD_EN | Load switch control | ESP32 IO4 via R8, SI2301 Gate | --- ## PARASITIC AND SIGNAL INTEGRITY CONSTRAINTS Please consider the following parasitic effects when placing components and routing: **I2C bus parasitics:** The I2C specification allows maximum 400pF total bus capacitance. With 4 devices on the main bus (ESP32, VEML7700, FDC1004, TCA9548A) plus the multiplexed sub-buses, keep total SDA/SCL trace length under 50mm. Route SDA and SCL as a parallel differential pair with 0.15mm clearance between them. Do not route I2C traces near switching power lines or under the antenna keep-out zone. **FDC1004 CIN1/CIN2 parasitic capacitance — CRITICAL:** Any stray capacitance on CIN1/CIN2 traces directly offsets the soil measurement. Each picofarad of parasitic capacitance reduces measurement range. Requirements: - Keep CIN1/CIN2 trace length under 15mm from FDC1004 pins to prong entry point - Route on Bottom layer only, no layer changes (vias add ~0.5pF each) - Add copper guard ring (connected to SHLD1/SHLD2=GND) completely surrounding each CIN trace on the same layer — this shields the trace from external fields - Maintain 0.5mm spacing between CIN1 trace and CIN2 trace (and their guard rings) - The interdigital soil electrodes on the prongs: finger width 0.8mm, gap 0.8mm, finger length 25mm, approximately 15–20 alternating fingers per electrode These traces have NO soldermask (fully exposed copper, ENIG finish) **BQ24090 switching node:** The BQ24090 is a linear charger, NOT a switching regulator, so there is no switching noise. However, it dissipates power as heat. The primary constraint is thermal, not EMI. Keep input/output bypass capacitors (C10, C11) within 2mm. **ESP32-C3 antenna zone:** Mandatory keepout: no copper, no traces, no vias, no components in the area directly beneath and 3mm around the ESP32 module antenna. The antenna is on the left side of the module. Orient the module so the antenna faces toward the top or side edge of the board. **Power supply decoupling placement:** All 100nF decoupling capacitors MUST be placed within 1mm of their associated VCC/VDD pin. The parasitic inductance of a longer connection nullifies the effect. Place decoupling on the same layer as the IC where possible. The 10µF bulk cap (C3) can be up to 5mm from the LDO output. **Thermal gradients and temperature sensor placement:** The two SHT40 sensors measure temperature via an on-chip bandgap reference. Self-heating of nearby components creates a thermal offset error. Known heat sources on this board and their typical power dissipation: - BQ24090: up to 500mW during USB charging - ME6211 LDO: 40–90mW at typical load - ESP32-C3: 15–25mW in active mode (WiFi), 0.02mW in deep sleep Required minimum distances from any SHT40: - From BQ24090: ≥12mm (critical) - From ME6211 LDO: ≥8mm - From ESP32-C3: ≥5mm (less critical — low dissipation) --- ## THERMAL MANAGEMENT REQUIREMENTS The device will be used outdoors in ambient temperatures from -10°C to +50°C. The case is a sealed or semi-sealed plastic enclosure approximately 35×35×80mm. Internal temperature rise above ambient must be kept below +8°C during USB charging. **BQ24090 thermal design:** - Thermal pad (exposed pad on DSBGA package): connect to copper area on both layers - Top layer: copper fill area ≥ 1cm² directly under and around IC - Bottom layer: mirrored copper fill area ≥ 1cm² connected via thermal vias - Minimum 4 thermal vias under pad: 0.3mm drill, 0.6mm pad, evenly distributed - These thermal vias conduct heat to bottom layer copper which acts as a heatsink - In the case design (outside scope of PCB): a thermally conductive pad between the PCB bottom copper and the plastic case back wall improves heat transfer **ME6211 LDO thermal design:** - Low dissipation at typical 50–80mA load: (4.0V - 3.3V) × 0.075A ≈ 52mW - This is well within SOT-23 package limits (max ~300mW at 25°C ambient) - Standard copper pour around package is sufficient - No additional thermal vias required unless load consistently exceeds 150mA **Fire safety note:** At no point should any trace carry more than its rated current. Power traces (VBAT, VCC) should be minimum 0.5mm for up to 500mA. The USB VBUS trace from J1 to BQ24090 carries up to 500mA — use 0.8mm trace. Add a polyfuse (PTC resettable fuse) 500mA on VBUS line between J1 and BQ24090 for short-circuit protection (LCSC C178886, 0805 package). --- ## WEATHERPROOFING DESIGN GUIDANCE (for PCB layout decisions) The board will be coated with conformal coating after assembly, EXCEPT: 1. SHT40-AD1F-R2 (U8 external sensor) — the PTFE filter cap must remain uncoated 2. VEML7700 (U2) — photodiode window must remain uncoated and unobstructed 3. Interdigital soil traces on prongs — must remain bare copper (ENIG) for soil contact 4. USB-C connector J1 — coating would block the port 5. Battery JST connector — coating would block connector mating For the PCB layout, implement the following to support weatherproofing: - Place U8 (SHT40 external) and U2 (VEML7700) in designated "coating exclusion zones" clearly marked on the silkscreen layer with dashed boundary lines - Add silkscreen labels: "NO COAT" next to U8 and U2 - Add silkscreen label: "EXPOSED — SOIL ELECTRODES" on the prong traces - The board outline on the prong section must have no sharp corners — use R1mm rounded corners where prongs meet the head section to prevent cracking when the device is pushed into soil --- ## INTERDIGITAL SOIL ELECTRODE SPECIFICATION (prong section) The bottom two prongs of the board ARE the soil moisture sensor. Trace parameters for the interdigital (comb/fork) capacitive electrodes: - Layer: Bottom copper - Trace width: 0.8mm - Gap between adjacent fingers: 0.8mm - Number of fingers per electrode: 16 (8 connected to CIN1, 8 to CIN2, alternating) - Finger length: 25mm - Connection point: at the top of the prongs where they join the head section - Guard ring: GND copper guard ring around the entire interdigital pattern on Bottom layer - NO soldermask over any part of the interdigital pattern - The two electrodes (SOIL_A and SOIL_B) must be symmetrically distributed so that a uniform electric field forms between them when immersed in soil - Add stitching GND vias around the prong perimeter every 8mm --- ## SILKSCREEN AND REFERENCE DESIGNATORS All components must have visible reference designators on the silkscreen layer. Minimum text size 0.6mm height. Add the following board information: - Top left: "SmartPlant v1.0" - Top right: "riccardo.schiavo.1" - Date code placeholder: "DATE: ______" - Near J1: PIN 1 marker and "USB-C POWER + FLASH" - Near U8: "EXTERNAL SENSOR — NO COAT" - Near prong junction: "SOIL ELECTRODES — NO MASK — ENIG" - Near ESP32 antenna area: keepout boundary marker --- ## I2C DEVICE MAP (for firmware reference) | Address | Device | Bus | Notes | |---------|--------|-----|-------| | 0x10 | VEML7700 (U2) | Main I2C | Direct connection | | 0x50 | FDC1004 (U4) | Main I2C | Direct connection | | 0x70 | TCA9548A (U5) | Main I2C | I2C multiplexer | | 0x44 ch.0 | SHT40 internal (U3) | TCA9548A channel 0 | Via mux | | 0x44 ch.1 | SHT40 external (U8) | TCA9548A channel 1 | Via mux | --- ## FINAL NOTES FOR FLUX AI I trust Flux AI's judgment on: - Exact component placement optimization within the constraints above - Via placement and layer assignments for non-critical signals - Polygon fill strategy and via stitching density - Any minor trace re-routing needed to clear DRC errors - Silkscreen label exact positioning to avoid overlap with pads Please prioritize in this order: 1. Electrical correctness (no DRC errors, no antenna violations) 2. Thermal management (BQ24090 copper, SHT40 distance from heat) 3. Signal integrity (FDC1004 CIN guard rings, I2C trace length) 4. Manufacturability (SMT assembly friendly, no isolated pads, no acute angles) 5. Physical compactness within the fork shape outline Generate a complete 2-layer PCB ready for Gerber export to PCBWay.

2-layer SELV ESP8266 smart relay logic board using an ESP-12F module, MCP1700-3302E 5V-to-3.3V LDO, exact 2x7 relay/control connector pinout, 4-pin UART programming header, GPIO0 flash test point, active-low GPIO2 status LED, power and GPIO test points, 55x45 mm board outline, top-side assembly, bottom solid ground pour, ESP-12F antenna keepout, 4 M3 mounting holes, and silkscreen connector labels for production use.

Integration baseline for an Espressif ESP32-S3-WROOM-1-N16R8 module with integrated PCB antenna, native USB, 16MB flash, and 8MB PSRAM. This project currently documents selection constraints, power and boot requirements, RF keepout expectations, and acceptance criteria for later schematic and PCB implementation.

4-layer marine GPS timing and communication device using nRF52840, u-blox ZED-F9P GNSS with external active antenna via u.FL, 915 MHz LoRa radio, Li-ion battery with USB-C charging, separate clean GNSS LDO and digital 3.3V rail, SPI memory LCD, RGB LEDs, buzzer, and 6-axis IMU. PCB target is a 70 mm circular layout with strict RF zoning, dedicated ground plane, 50 ohm RF traces, physical separation between GNSS and LoRa, and low-noise placement suitable for harsh marine environments.

Resonate Pendant golden reference design. Board is a 39 mm x 63 mm portrait rectangle with 5 mm corner radii, 2-layer FR4, 0.8 mm thickness, 1 oz copper on both layers, matte black top solder mask, no bottom solder mask, ENEPIG finish, and no silkscreen on either side. Allowed components only: U1 STM32L052C8T6, U2 CH340E, U3 BQ24210DQCT, C1 10uF, C2 4.7uF, C3-C7 100nF, R1 24k, R2 1k, R3 10k, D1 green 0402 LED, MAG1-MAG4 magnetic pads, J1 solar solder pads, J2 battery solder pads, TP1-TP4 test pads. Required top artwork: golden-ratio grid lines and gold circles on F.Cu with mask openings, decorative only, 0.8-1.0 mm width, at least 0.5 mm from active traces. Required bottom artwork: exposed ENEPIG bottom copper split into FREQ_OUT 61.8 percent and GND 38.2 percent with an exact 0.20 mm S-curve isolation gap, no vias through bottom except one PA4-to-FREQ_OUT via at the extreme edge. Functional requirements: MAG1 and J1 VIN feed U3 IN, U3 OUT feeds J2 battery pad and system VBAT, MAG2 to U2 UD+, MAG3 to U2 UD-, MAG4 to common ground, U2 TX to U1 PA10, U2 RX to U1 PA9, U1 PA4 to bottom FREQ_OUT, U1 PA5 to R2 then D1 to GND, U3 ISET to R1 to GND, U3 TS to R3 to GND, decoupling exactly as specified. Prohibited items: external crystal, JST connectors, wireless module, antenna, separate regulator IC, ESD protection IC, USB-C connector, through-hole parts, bottom solder mask, silkscreen, more than three ICs, or any unapproved substitutions.

FlowState Headband EVT1 — 4-Channel EEG Calibration Device Closed-loop EEG neurofeedback headband for theta/beta baseline calibration. 4-layer mixed-signal PCB, 40x30mm. Core ICs: - ADS1299-4PAG (TI) — 4-channel 24-bit EEG analog front end, SPI interface, 250 SPS - nRF5340 (Nordic) — Dual-core BLE 5.3 SoC, 128 MHz app core + 64 MHz network core Key requirements: - Separate analog and digital power domains (dual LDO: LP5907 for AVDD, AP2112 for DVDD) - Split analog/digital ground planes with single-point connection - 6 electrode inputs (4 active + 1 reference + 1 DRL) with individual TVS ESD protection on each - LIS2DH12 accelerometer (I2C) for motion artifact detection - MCP73831 USB-C battery charging (300-500 mAh LiPo) - 2.4 GHz chip antenna or PCB trace antenna at board edge with 10mm keepout - Conformal coating for sweat/moisture protection Reference designs: - Analog front-end: TI ADS1299 EVM (SBAS499) - Digital/BLE: Nordic nRF5340 DK reference schematic Critical constraint: Microvolt-level EEG signals — analog input routing and power supply filtering are the highest-priority layout concerns.

SCADA Sensor Node v2.1 using a Heltec WiFi LoRa 32 V4 module with separate +5V and board-generated +3V3 rails, ADS131M08 8-channel ADC front end, TCA9548A I2C multiplexer, TMP102-based fan control, ULN2003A relay and fan driver, CT/pressure/analog/One-Wire/vibration/humidity/Qwiic/flow/digital sensor interfaces, relay outputs, fan connector, brownout sensing, and a 200 mm x 140 mm 2-layer layout with Heltec keepout, antenna clearance, mounting holes, and DIN-rail slots.

Datasheet-driven MFRC522 RFID reader PCB intended to replicate RC522 module behavior at 13.56 MHz with a 3.3 V nominal supply, 2.5 V to 3.3 V operating range, and RC522-style 8-pin host header compatibility. The MFRC522 datasheet is the authoritative source for pin usage, power rail relationships, oscillator requirements, reset/IRQ handling, and antenna interface topology. AVDD, DVDD, and TVDD must be tied to the same 3.3 V rail; PVDD must be equal to or lower than DVDD; unused MFIN must be tied to SVDD or PVSS; SVDD must be tied to a valid supply if not used independently. The design must use a 27.12 MHz crystal meeting CL 10 pF and ESR <= 100 ohms, local 100 nF decoupling on each MFRC522 supply grouping plus bulk capacitance, and an RF front-end based on the MFRC522 application diagram and reference reader matching/tuning network. PCB priorities are short crystal and RF connections, compact placement of decoupling capacitors at supply pins, solid ground reference, and protected antenna region with minimal digital routing through the RF area.

SmartDeskPet v1.0 Shield Stage 1 status: - Goal: 5V input -> dual AMS1117-3.3 rails (+3V3_MCU and +3V3_WIFI) with common GND. - Note: Keep power nets explicitly named (avoid unnamed nets) to keep ERC happy. Stage 1 completion checklist: - Mark J1 Pin_1 (+5V) as a Power Output pin to satisfy ERC power-driver checks. - Verify all GND symbols/returns are on the same GND net. - Keep +5V_SERVO isolated from the main +5V net (only share GND). Stage 2 preparation notes (MPN/LCSC + layout constraints): - MPN/LCSC targets to define before Stage 2 exit: - AMS1117-3.3 (SOT-223): set exact MPN and (optionally) LCSC PN for both U1 and U2. - 100nF capacitor (0603): set MPN/LCSC for all 0603 100nF decouplers. - 4.7k resistor (0603): set MPN/LCSC for I2C pull-ups R1 and R2. - 1000uF bulk capacitor (radial): set MPN/LCSC for C7 (CP_Radial_D10.0mm_P5.00mm). - DC005 power jack/regulator input: select exact DC005 footprint + MPN/LCSC (if used). - 2.54mm headers/sockets: set MPN/LCSC for H1, H2, J1, J3, J4, J5, P3, P4, P5, and J2. - ESP-01S antenna keepout: - Reserve a copper keepout under and in front of the ESP-01S onboard antenna. - No copper pours/traces/components in the antenna region (top and bottom) per module guidelines. - H1/H2 header spacing: - Maintain 1000 mil spacing between H1 and H2 header centerlines (shield mechanical requirement). - Silkscreen placeholders: - Add silkscreen labels for: 5V IN, GND, +3V3_MCU, +3V3_WIFI, SERVO1, SERVO2, I2C SDA/SCL, DHT11, ASRPRO UART2, ESP-01S UART3. - Add placeholder text for: MPN, LCSC, board revision, and date code. Stage 3 layout constraints (placement and routing guidance): - Connector placement strategy: - Place H1 and H2 first to lock the shield mechanical interface; enforce 1000 mil spacing. - Place J1 and any DC005 input at the board edge for easy access. - Designated power area planning: - Group U1, U2, and C7 near the 5V entry point; keep high-current 5V and regulator loops short. - Use wide copper for +5V and any servo supply; stitch GND around power section. - Antenna keepout boundaries: - Place J2 (ESP-01S socket) at a board edge with the antenna facing outward. - Enforce a top-and-bottom copper keepout in the antenna region; keep noisy power traces away.

Architectural Lavender Translation Collar – ESP32‑S3 Wi‑Fi + LoRa, USB‑C, Li‑ion, low‑power design Overview Experience a cutting-edge IoT solution with this low‑power board built around the ESP32‑S3‑MINI‑1‑N8. Designed for seamless Wi‑Fi (2.4 GHz), BLE, and LoRa (868 MHz) connectivity, this board integrates ENS161 and ENS210 sensors over I2C alongside an RFM95W‑868 LoRa radio on SPI. It is powered via a 3.7 V Li‑ion cell with USB‑C charging up to 500 mA, complete with full battery protection, a robust 3.3 V rail tailored for Wi‑Fi burst currents, and per‑peripheral power gating to enhance energy efficiency. Core Features • MCU: ESP32‑S3‑MINI‑1‑N8 equipped with an onboard PCB antenna for 2.4 GHz Wi‑Fi/BLE, ensuring optimal wireless performance. • Sensors: Integrated ENS161 and ENS210 sensors utilize a shared I2C bus with controllable 4.7 kΩ pull‑ups for streamlined communication. • LoRa Radio: The RFM95W‑868 module, connected via SPI, enables long‑range communication at 868 MHz. Power & USB‑C Connectivity • Battery: A reliable 3.7 V 1200 mAh Li‑ion battery connected via a right‑angle JST‑PH 2‑pin connector features built‑in battery protection. • Charging: The USB‑C receptacle, with CC resistors and TVS protection on D+/D− along with series resistors, supports fast, safe charging with a current limit of 500 mA. • Regulation: A dedicated 3.3 V regulator capable of handling Wi‑Fi burst currents coupled with bulk and high‑frequency decoupling ensures stable operation, supported by status LEDs indicating power and charge states. Low‑Power Control • Peripheral Management: Load switches allow selective power‑gating of the ENS161, ENS210, and RFM95W modules, controlled directly by ESP32‑S3 GPIOs. • Energy Efficiency: Controllable I2C pull‑ups minimize idle current, vital for prolonged battery life in IoT applications. RF and Antenna Integration • 2.4 GHz: Utilizes the integrated PCB antenna on the ESP32‑S3 with proper ground/metal keep‑out zones for optimal signal integrity. • 868 MHz: Features a controlled‑impedance feed from the RFM95W to a PI matching network (C‑L‑C pads) with flexible antenna options—selectable via SMA connector, chip antenna, or PCB trace—and includes RF ESD protection. Connectivity & Debug Features • USB‑C Interface: Provides secure data connectivity with integrated safeguards and proper terminations. • Debugging: A comprehensive programming/debug header exposes EN, BOOT, and UART lines, with test points on key rails and buses (3V3, VBAT, SCK, MOSI, MISO, SDA, SCL, RESET/EN, GND) to simplify development and troubleshooting. Design Verification • Rigorous ERC/DRC and decoupling checks ensure adherence to component ratings and optimal signal routing. • Maintain RF keep‑outs and impedance‑controlled traces for both 2.4 GHz and 868 MHz paths, securing reliable performance even during high‑intensity operations. #IoT #ESP32S3 #LoRa #LowPowerDesign #USB-C #WirelessConnectivity #BatteryPowered #RFDesign

Smart Glasses BLE Audio & RF PCB with Nordic nRF54L15 MCU and 3‑Pad RF Pi‑Match Network for Johanson 2450AT18B100E Chip Antenna (4‑Layer Microstrip, Antenna Keepout, Impedance‑Controlled RF Path)

Production-Ready 18×18 mm BLE Grip Sensor with nRF52832 RF Module, BMA456 IMU, CR2032 Power, and 2.4 GHz Antenna Keepout

Compact 4-Layer ESP32-S3-DevKitC-1 Nano-Style Carrier Board with I²S Audio, Class-D Amp, MicroSD, LiPo Power, WS2812B, and IR; featuring updated all-layer antenna keepout, additional decoupling capacitors on 5 V/3.3 V rails, four M3 mounting holes, finalized rounded-corner PCB outline and hand-friendly width, centered ESP32-S3-DevKitC-1 and symmetrically aligned MicroSD/I²S mic, centered bottom silkscreen title text, and zero-error ERC/DRC; layout is finalized and ready for routing #ESP32S3 #DevKitC1 #antennaKeepout #decoupling #M3MountingHoles #routingReady

Isolated Polyphase IIoT Energy Meter with ESP32-S3-WROOM-2-N32R16V & ADE9000 | UART Programming Pads | 100 nF Per-VDD Decoupling + 10 µF Bulk on 3.3 V Rail | Defined RF Antenna Keepout | USB-C UFP 5 V Input with eFuse | Maintained HV/LV Isolation

Smart Chair V1: ESP32-C3-based seat-occupancy and posture sensing hub with 4× FSR channels and IMU over I2C, featuring corrected USB-C power wiring with TVS protection, remapped I2C on IO4/IO5 with pull-ups, dedicated PROG_TX/PROG_RX/BOOT/EN test pads, and antenna keep-out zone #consumer-electronics #BLE #I2C #USB-C #IoT

This is an ESP32-C3 reference design based on the manufacturer's recommendations with a uFL SMD antenna and USB C on board #WiFi #ESP32-C3 #IoT #referenceDesign #simple-embedded #espressif #template #reference-design

This is an ESP32-C3 reference design based on the manufacturer's recommendations with a uFL SMD antenna and USB C on board #WiFi #ESP32-C3 #IoT #referenceDesign #simple-embedded #espressif #template #reference-design

Compact 2-Layer ESP32-WROOM-32E Ultrasonic Emitter Board with USB-C Auto-Programming, On-Board 12 V→3.3 V Buck, 3× Low-Side MOSFET Drivers, Optional U.FL Antenna, ESD/TVS Protection, RF/Power Partitioning, and Named Nets (PWR_12V_IN, 3V3, GND, DRV_CH1/2/3, LED_PWR/LED_NET/LED_EMIT) #ultrasonic #ESP32 #RFDesign #PowerDesign #PCBDesign

RF Module, ESP32-D0WD SoC, Wi-Fi 802.11b/g/n, Bluetooth, BLE, 32-bit, 2.7-3.6V, onboard antenna, SMD #RF #ESP32 #WiFi #BLE #commonpartslibrary

Welcome to the Radio Antenna/Micromodule Project – a cutting-edge design that fuses state-of-the-art radio antenna technology with a compact micromodule configuration to deliver robust wireless communication solutions. This innovative project emphasizes optimized component selection and circuit precision. For example, a standard current-limiting resistor (recommended 330Ω) has been considered to ensure efficient energy management when powering associated indicator LEDs. This design invites you to confirm your resistor value and further customize the electronics to meet dynamic signal and connectivity requirements, paving the way for exceptional performance in today's interconnected landscape. #RadioAntenna #Micromodule #ElectronicsDesign #WirelessCommunication #Innovation

Bluetooth, WiFi 802.11b/g/n, Bluetooth 4.2 Transceiver Module 2.412GHz ~ 2.484GHz Antenna Not Included, I-PEX Surface Mount #Module #RF #Transceiver #bluetooth #Wifi

An automatic satellite/planet tracker. It can precisely point an antenna or telescope to a moving spacecraft or tracking a planetary object.

An automatic satellite/planet tracker. It can precisely point an antenna or telescope to a moving spacecraft or tracking a planetary object.

An automatic satellite/planet tracker. It can precisely point an antenna or telescope to a moving spacecraft or tracking a planetary object.

The component under discussion is designed for advanced electronic systems, targeting applications that require reliable connectivity and precise data acquisition. Engineered by SEMTECH, a leader in high-performance analog and mixed-signal semiconductors and advanced algorithms, this module showcases its prowess in the realm of wireless technology. It incorporates the LR112x series chips, specifically mentioning the LR1120 and LR1121, which are notable for their low power consumption and robustness in communication capabilities. These chips cater to a variety of frequency bands, with explicit mentions of R915 and R868, indicating their suitability for a broad range of geographical regions and regulatory requirements. This module is particularly designed with an eye towards innovation in the domain of Internet of Things (IoT) applications, offering features that ensure seamless integration into existing technology with an emphasis on ease of deployment and operational efficiency. Key features highlighted include multiple onboard antennae options such as ANT_GNSS and ANT_WIFI, ensuring comprehensive connectivity solutions for different environmental and application requirements. Also notable is the mention of a VOD_RADIO and the inclusion of interfaces like SPI and BUSY signaling, underscoring the component's flexibility in system integration and communication protocol support. Furthermore, SEMTECH references specific considerations for design and regulatory compliance, indicating the component's targeted use in professional grade equipment and scenarios. The datasheet also hints at an evaluation-focused approach, with designations like "For evaluation only" and remarks on FCC approval status, suggesting that this component is positioned for development and testing in cutting-edge wireless applications. This focus on flexibility, regulatory compliance, and advanced connectivity options positions SEMTECH's component as a crucial asset for designers and engineers looking to innovate in the IoT and wireless communication sectors.

Conservative first-revision TIMI prototype built around ESP32-S3-WROOM-1-N16R8 with USB-C 5V input, native USB, 3.3V regulation, onboard MAX98357A audio out, external INMP441 header, status LEDs, buttons, UART debug header, required test points, and 4-layer antenna-conscious PCB constraints.

Production-defensible Rev B ear tag tracker using nRF9151 with separate LTE and GNSS antennas, solar-assisted LiPo charging, battery protection, SPI NOR flash, NFC, eSIM, I2C sensors, Tag-Connect SWD, grouped EVT test points, and RF/power zoning on a 40 mm x 24 mm 4-layer PCB.

Project Description: The Sweet Tomato Heat-Ray project focuses on the development of an advanced PCB design for the PawPulse Smart Collar – a dual-SoC device that integrates both BLE and cellular connectivity. The design features a compact 49mm x 35mm, 6-layer FR-4 board with optimized RF performance, robust power supply management, and critical layout considerations including precise keepout zones for antennas and optical paths. All mechanical and assembly aspects, including rounded corners and optimized signal routing using 0201, 0402, and 0603 components, have been meticulously documented. Note: Please be aware that the battery and its supporting components are not yet included. It is essential to add these components in future revisions to ensure full functionality and compliance with power requirements. #SmartCollar #PCBDesign #BatteryIntegration #ElectronicsDevelopment #RFDesign #InnovativeTech