CONTROL_RF_PCB is a standalone 4-layer rigid FR4 control, RF, GNSS, sensor, local actuator, local battery-cell, and solar-pass-through PCB for an outdoor livestock collar. Target board size is 120 mm x 80 mm with production-prototype design intent and JLCPCB/LCSC-compatible assembly where practical.
Intended Use
Outdoor livestock collar electronics module exposed to rain, mud, snow, dust, vibration, and impact.
Temperature target: -40C to +50C.
Not a bench development board; design should include production-style protection, test access, isolation, and keepouts.
What the Device Should Do
Run main control firmware on ESP32-S3-WROOM-1-N16R8.
Communicate via 915 MHz LoRa using an SX1262 transceiver and external U.FL antenna.
Receive GNSS position data from a u-blox MAX-M10S module with external U.FL antenna.
Read motion from BMA400 accelerometer over I2C.
Read ambient/local temperature from TMP117 over I2C.
Capture audio using ICS-43434 I2S MEMS microphone.
Drive one off-board vibration motor and one off-board waterproof piezo buzzer through low-side MOSFET drivers.
Provide local 2 x 32700 LiFePO4 cell solder-tab/holder pads tied to the shared 1S pack bus.
Pass solar panel A input through to an external power board; this board does not charge the battery.
Carry an isolated high-voltage electrode pad from an external stimulation board; this board does not generate high voltage.
Main Features
ESP32-S3 MCU with EN/reset, IO0 boot/programming, UART debug/programming header, and test points.
SX1262 LoRa RF section with 915 MHz matching/pi tuning footprint, RF ESD, U.FL, and antenna keepout.
MAX-M10S GNSS section with filtered 3V3 supply, backup supply footprint if supported, RF ESD, U.FL, and antenna keepout.
I2C sensor bus with pull-ups and sensor interrupt nets.
I2S MEMS microphone with acoustic port keepout and port marker.
Local actuator drivers with gate resistors, pulldowns, transient protection, and test points.
Soldered flex-tail landing area with four physical zones: low-voltage signal, high-current battery, solar pass-through, and isolated HV electrode.
Extensive labeled test points.
System Architecture
Diagram
Hardware Subsystems
Power
Required nets: CELL_PACK_PLUS, PACK_GND, 3V3.
3V3 is received already regulated from external power board through soldered flex tail.
No charger, BMS, 3V3 regulator, or stimulation generator on this PCB.
Bulk capacitance near flex tail 3V3 input.
0.1uF decoupling near every IC.
10uF or larger near ESP32, SX1262, and GNSS.
Battery and solar voltage sense dividers to ESP32 ADC with protection/clamp as needed.
Compute and Debug
ESP32-S3-WROOM-1-N16R8 main MCU.
EN/reset RC circuit and reset access.
IO0 boot/programming circuit.
UART programming/debug header.
Test points: ESP_EN, ESP_IO0, UART_TX, UART_RX, 3V3, GND.
RF / GNSS
SX1262 LoRa on SPI with LoRa control pins.
915 MHz matching network and pi-network tuning footprint.
U.FL antenna connectors and ESD protection.
MAX-M10S GNSS on UART with clean filtered 3V3 supply and optional backup supply footprint if supported.
RF and GNSS sections near outside board edge with antenna keepouts and no copper under keepouts.
TMP117 I2C temperature sensor: I2C_SCL, I2C_SDA; place away from heat sources.
ICS-43434 I2S MEMS microphone: MIC_BCLK, MIC_WS, MIC_SD; place away from motor, buzzer, high-current pads, switching noise, and vibration sources.
Actuators
Vibration motor A on connector/pads J_VIB_A with N-channel low-side MOSFET, gate resistor, gate pulldown, flyback/transient protection, and test points VIB_A_PWM and VIB_A_OUT.
Waterproof piezo buzzer A on connector/pads J_BUZZ_A with N-channel low-side MOSFET, gate resistor, gate pulldown, transient protection if needed, and test points BUZZ_A_PWM and BUZZ_A_OUT.
Electrode Isolation
J_ELECTRODE_A isolated pad/connector on ELECTRODE_A_HV.
HV arrives from external stimulation board through soldered flex tail.
Keep ELECTRODE_A_HV isolated from RF, GNSS, microphone, 3V3, I2C, SPI, and UART.
Add copper keepout and silkscreen warning around electrode route.
Target assembly through JLCPCB/LCSC where practical.
Exposed soldered flex-tail landing area instead of FPC/ZIF connector.
Production prototype: include fiducials/alignment marks, test points, protection, keepouts, and silkscreen warnings.
Firmware-Relevant Hardware Requirements
ESP32-S3 pin assignment must support LoRa SPI, GNSS UART, I2C sensors, I2S microphone, PWM actuator outputs, ADC battery/solar sensing, and flex-tail external control/status nets.
Boot and reset access required through IO0 and EN.
UART programming/debug header required.
Firmware starter file will be generated after schematic pin assignments are finalized.
Physical Design Expectations
Board target size: 120 mm x 80 mm.
RF and GNSS near outside board edge.
Antennas clear of battery cells and flex tail.
Microphone away from vibration motor, buzzer, high-current pads, and switching noise.
TMP117 away from heat sources.
Electrode route isolated with copper keepout and HV warning.
No autorouting until placement is approved.
Important Design Decisions
Use module-based ESP32-S3 to avoid custom WiFi/BLE RF design.
Use external U.FL antennas for LoRa and GNSS.
Keep charging, BMS, 3V3 regulation, and stimulation generation off-board per user request.
Use a 4-layer stackup with solid L2 ground plane for RF return paths and signal integrity.
Assumptions
SMD assembly is preferred because this is a production-prototype board and JLCPCB/LCSC assembly is targeted.
External power board can supply sufficient 3V3 peak current for ESP32-S3 WiFi/BLE plus SX1262 transmit and GNSS operation.
Flex-tail pads and battery solder pads may require custom footprint/layout nodes if exact mechanical drawing is not available.
Exact RF matching values may need tuning with VNA measurements; schematic will include pi-network footprints and nominal reference values from datasheets/reference designs where available.
Change Notes
Initial specification created from the user request.