Temperature and Humidity Sensor Node Design
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4/7 Add all schematic components with correct values and role metadata
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Read schematic.
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5/7 Wire power path, MCU, BMP280 I2C, OLED SPI/FPC, encoders, LED, reset, ADC divider, and decoupling
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Read schematic.
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No results for MCP23017 SOIC I2C GPIO expander.
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Completed design checks — found 163 issues.
Read schematic.
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6/7 Create firmware starter document grounded in schematic pin mapping
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- Renamed/described the project.
- Added project specification, power budget, and firmware starter files.
- Selected and added the ESP32-C3 SuperMini, BMP280, SH1107 OLED FPC connector, MT3608 boost module, MP1584EN buck module, reverse-polarity P-FET, controls, headers, LED, passives, and mounting holes.
- Wired the major power, I²C, SPI OLED, encoder, LED, ADC divider, and decoupling networks.
- Ran an ERC review pass; no matching ERROR/WARNING items were returned at that point.
- Created firmware starter code for PlatformIO/Arduino with BMP280, SH1107 display, battery ADC, encoders, Wi-Fi reconnect, and low-battery handling.
- Exact mini‑Tamiya footprint was not found; the schematic uses a 2-pin battery connector placeholder that should be replaced with the correct mini‑Tamiya part/footprint.
- The ESP32-C3 SuperMini library symbol used here does not expose EN/RST, so the tactile reset is implemented as a firmware reset request on GPIO9 rather than a true hardware reset.
- GPIOs are tight; encoder 2 switch shares the reset-request/OLED-reset net, which should be reviewed if separate reset and encoder-button behavior is mandatory.
- Before layout, a fresh review pass should be run again, any remaining pin/net naming issues cleaned up, and the exact battery connector/reset strategy finalized.
- PCB: rectangular, <= 60 mm x 40 mm, four M2.5 mounting holes in corners.
- Environment: -20 C to +50 C, vibration/field-handling tolerant, conformal-coating friendly.
- MCU: ESP32-C3 SuperMini preassembled module, socketed via 2 x 8 female 2.54 mm headers.
- Wireless: 2.4 GHz Wi-Fi 802.11 b/g/n and BLE 5.0 for phone configuration.
- Display: external Surenoo SOG128128A_T112 transparent 1.12 in PMOLED, SH1107, 128 x 128 px, 4-wire SPI via 12-pin 0.5 mm FPC at board edge.
- Sensor: BMP280 on 3.3 V I2C, address configurable 0x76/0x77.
- Controls: two KY-040 rotary encoders with integrated push buttons via 5-pin 2.54 mm headers, spaced about 25 mm apart on top/user side.
- Indicators: one 0805 status LED and tactile MCU reset button.
- Source: 2S LiPo 6.4-8.4 V via mini Tamiya connector.
- Input protection: P-channel MOSFET reverse-polarity protection, SPDT slide switch power on/off.
- 13.5 V rail: MT3608 boost daughter-board on 2.54 mm headers for OLED VPP.
- 5 V rail: MP1584EN buck daughter-board on 2.54 mm headers feeding ESP32-C3 SuperMini USB-in pin.
- 3.3 V logic rail: generated by ESP32-C3 SuperMini onboard regulator and exported to BMP280, display logic, pull-ups, and controls.
- Caps: 100 uF electrolytic at battery input; 10 uF + 100 nF at BAT_SW, 5V, 13V5, and 3V3 rails.
- OLED IREF to GND: 1 MOhm 0603.
- OLED VCOMH to GND: 4.7 uF ceramic.
- SPI signals from ESP32-C3 to FPC: SCLK, MOSI, CS, D/C, RST.
- VDD/logic at 3.3 V, VPP at 13.5 V, common GND.
- Battery ADC divider sized for <= 3.3 V at 8.4 V input.
- Firmware-side low-voltage cutoff threshold: 6.4 V battery.
- Arduino/PlatformIO starter firmware will include BMP280 reads, OLED update path, encoder inputs, ADC battery monitor, Wi-Fi/BLE placeholders, and status LED.
- ESP32 antenna must face board edge with copper keepout.
- OLED FPC and battery connector on opposing edges.
- Encoder headers on top/user-facing surface with about 25 mm spacing.
- DC-DC module trimmers must remain accessible after assembly.
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