Meshtastic Sensor Node Schematic

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  • Connected J1:VBUS_A, J1:VBUS_B, U7:VCC, C17:P1, C18:P1, C22:P1, C23:P1 to ^SOLAR_IN
  • Connected U7:MPPT, R8:P1, R9:P2 to ^MPPT_SET
  • Connected R8:P2, J1:VBUS_A, J1:VBUS_B, U7:VCC, C17:P1, C18:P1, C22:P1, C23:P1 to ^Net 1
  • Connected R9:P1, C26:P2, C25:P2 to ^GND
  • Connected U7:COM, R7:P1 to ^CHG_COMP
  • Connected R7:P2, C26:P1 to ^Net 2
  • Connected U7:BAT, R10:P1 to ^BAT_CHG
  • Connected U7:CSP, R10:P2, SW1:1, J2:1, C24:P1, C25:P1 to ^BAT
  • Connected SW1:2, U6:VIN, C19:P1 to ^VSYS
  • Disconnected U7:BAT, SW1:1, J2:1, C24:P1
nets { net 3V3 = R15:P1, C20:P1, C7:P1, R2:P1, C5:P1, C3:P1, C4:P1, C13:P1, U6:CE, R4:P1, R3:P1, R12:P1, C14:P1, U2:VBAT_IO, U2:VBAT, U1:VDD_SPI, U1:VDDA2, U1:VDDA1, U1:VDD3P3_RTC, U1:VDD3P3_CPU, U1:3, U1:2, U2:VDD_IN, C11:P1, C6:P1, R11:P1, R16:P1, U6:VOUT, C8:P1, C2:P1, C12:P1, R1:P1; net GND = X2:2, X1 GND - X1 GND:GND, R9 P1 - C26 P2:GND, C25:P2, C26:P2, R9:P1, U4 GND - U5 GND:GND, C3:P2, R13 P2 - R14 P2:GND, C17:P2, C15:P2, U7:GND, C1:P2, C2:P2, J1:GND_A, C6:P2, D1:A, C14:P2, R13:P2, GND:GND, U2:GND_1, U2:GND_2, C4:P2, U2 GND_5 - U3 GND:GND, R14:P2, C9:P2, Q1:S, C13:P2, U2:GND_5, U2:GND_4, X1:2, C18:P2, X1:4, C12:P2, Q2:S, U2 GND_2 - U2 GND_3:GND, J2:2, LED2:K, R5:P2, C19:P2, U5:GND, U3 GND - U4 GND:GND, C20:P2, J1:GND_B, U2:GND_3, C21:P2, C7:P2, C11:P2, X2:4, R6:P2, C10:P2, C24:P2, U1:GND, C5:P2, U6:GND, C16:P2, LED1:K; net USB_CC2 = J1:CC2, R14:P1; net VBUS_5V = U5:VCC, D1:2, D1:1, R8:P2, C23:P1, C22:P1, C18:P1, C17:P1, U7:VCC, J1:VBUS_B, J1:VBUS_A; net DONE = R12:P2, U7:~DONE; net USB_CC1 = J1:CC1, R13:P1; net CHRG = U7:~CHRG, R11:P2; net MPPT_SET = U7:MPPT, R9:P2, R8:P1; net CHG_COMP = U7:COM, R7:P1; net Net 2 = R7:P2, C26:P1; net BAT_CHG = U7:BAT, R10:P1; net BAT = U7:CSP, C25:P1, C24:P1, J2:1, SW1:1, R10:P2; net VSYS = SW1:2, C19:P1, U6:VIN; }

flux

Work done
  • Audited the existing U7 charger block against datasheet guidance and identified the missing support elements: input bypassing, COM compensation, MPPT divider, and BAT-path current sense/filtering.
  • Added new support parts around U7: C22, C23, C25, C26, R7, R8, R9, and R10.
  • Wired the new network so the solar/input side is bypassed at U7VCC, U7MPPT has a divider, U7COM has the required RC compensation, and the BAT path now includes a current-sense element between U7BAT and the project BAT rail.
Success criteria review
  • ✅ The missing passive support network was substantially added around U7.
  • ✅ BAT, VSYS, and the charger-related nets now have explicit connectivity reflecting the intended power path.
  • ❌ I could not finish verification and documentation because execution is blocked in this session before I can perform the final schematic review pass and update the project document.
  • ❌ One net naming cleanup is still needed: the input rail write reused the existing VBUS_5V net instead of creating a distinct solar-specific label, so I could not complete the requested net-label cleanup/documentation step.
Next steps The charger support components are now in place, but the project still needs one cleanup pass to rename the input rail appropriately, run a targeted review on the U7 section, and update Project Specification. Once execution is available again, I can finish those remaining steps.
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U1
Manufacturer Part Number
ESP32-S3FN8
U7
Project Specification
Overview
A Meshtastic-compatible solar-powered sensor node built around an ESP32-S3FN8 MCU and SX1262 LoRa transceiver. The design includes LiPo battery support, solar charging, 3.3 V regulation, USB-UART flashing with auto-reset, external sensor inputs, status LEDs, and an RF path to an SMA antenna connector.
Architecture
Diagram



  
    
  
  
    
  































USB-C node_5V Input
LiPo Charger
Solar Input
LiPo Battery
Battery Switch
3.3V LDO
ESP32-S3 MCU
SX1262 LoRa Radio
Sensor Interfaces
USB-UART Bridge
Auto Reset MOSFETs
RF Matching Network
SMA Antenna
Status LEDs
Functional Blocks
  • ESP32-S3FN8 MCU with external 40 MHz crystal, boot/reset support, and decoupling.
  • USB-UART programming interface with automatic boot and reset control.
  • SX1262 LoRa transceiver with crystal, RF matching/filter network, and SMA connector.
  • Analog sensor inputs for MQ-2 smoke sensing and rain sensing with ADC-safe scaling.
  • Solar/LiPo charging subsystem and battery-powered 3.3 V rail.
  • Status indication LEDs for power and MCU activity.
Design Decisions
  • Use USB-UART instead of native USB so the flashing interface remains explicit and compatible with standard ESP32 auto-reset behavior.
  • Use a simple LiPo charger plus solar input path to satisfy the requested solar charging requirement.
  • Use an LDO for 3.3 V generation because the node is battery powered from a single-cell LiPo and low noise is preferred for RF and ADC sections.
  • Keep external sensor inputs on headers so MQ-2 and rain sensor modules can be attached without forcing a specific transducer footprint.
Intended Nets
  • Power: 3V3, GND, VBUS_5V, BAT, VSYS, SOLAR_IN
  • ESP32 programming/control: U0TXD, U0RXD, EN, BOOT, DTR, RTS
  • LoRa: LORA_SCK, LORA_MOSI, LORA_MISO, LORA_NSS, LORA_BUSY, LORA_DIO1, LORA_NRST
  • Sensors: MQ2_AO, MQ2_DO, RAIN_AO
  • Status: LED_PWR, LED_STATUS
Notes
This specification records the intended architecture before schematic completion. Exact GPIO assignments and part substitutions may be refined during implementation based on library availability and pin compatibility.

  • Overview

  • Architecture

  • Functional Blocks

  • Design Decisions

  • Intended Nets

  • Notes