Temperature and Humidity Sensor Design

flux

0:00

Work completed:
  • Updated project description and system architecture
  • Removed BG96 (U5), HC-05 (U12), and redundant LDO (U3)
  • Added EC800M (U5) and connected its UART/USB/SIM pins to U6/J4
  • Added CC pull-down resistors and ESD diodes on J1 CC1/CC2, D+/D–
  • Routed J1 VBUS → U2 (eFuse) → U4 (ideal diode) → U10:VIN
  • Confirmed presence of U10 (TPS62177), U11 (TPS63070), and Q1 (DMP3013SFV) on the 3.3 V and 8.5 V rails
  • Added 100 nF decoupling capacitor at U10:VIN
Remaining tasks:
  • Add 100 nF decoupling capacitors at U7:3.3 V, U8:VD, M1:3V0, and U9:VDD_EXT
  • Add bulk capacitors, RC snubber (R5, C21), and TVS (D3) on the 8.5 V printer rail
  • Create PRINTER_8V test point
  • Route ESP32 UART0 (U7) to printer header with ESD protection
  • Lock SPI (CLK/MOSI/CS/DC/RESET/backlight) and I2S/audio paths; verify decoupling on EC800M/ESP32
  • Add test points on 5 V, 3.3 V, 8.5 V, and UART nets
  • Run ERC/DRC checks and resolve violations
  • Apply placement constraints (8 mm clearance for RF/audio/HC zones)
Success criteria status:
  • EC800M and SIM connections: ✅
  • Protected USB-C 5 V path: ✅
  • TPS62177 as sole 3.3 V source with partial decoupling: ⚠️ (additional caps needed)
  • TPS63070 + high-side FET producing 8.5 V/3 A rail: ⚠️ (protections and test point need completion)
  • ESP32 dedicated to Bluetooth printer: ⚠️ (UART routing pending)
  • Locked display/audio/radio paths and ERC/DRC: ⚠️ (pending)
Recommended next step: Add the remaining decoupling, bulk, and protection components; place test points; then run ERC/DRC to finalize schematic integrity.
100 days
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    Quick Moccasin Replicator thumbnail
    Voice-Controlled LTE Print-on-Demand Terminal (Quectel EC800M + ESP32-WROOM-32D BT Printer Interface, Protected USB-C 5 V Input, Unified 3.3 V Logic Rail, 8.5 V/3 A Printer Supply with High-Side FET & Protections, Locked Display/Audio/Radio I/O — Layout-Ready) #EC800M #USB-C-Protected #3V3Only #8.5V3A #LockedI/O

    Properties

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    V
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    V
    Diagram
    


  
    
  
  
    
  



















UART/USB

SPI

I2S

Differential Audio

UART

Bluetooth













"USB-C Port"
"5V eFuse (U2)"
"Ideal Diode ORing (U4)"
"3.3V Buck TPS62177 (U10)"
"8.5V Boost TPS63070 (U11)"
"EC800M Cellular Module (U9)"
"STM32L433 MCU (U6)"
"ESP32-WROOM-32D Printer BT (U7)"
"TFT node_240x320 Display (M1)"
"CS4272 Audio Codec (U8)"
"LM4861 Speaker Amp (U1)"
"Thermal Printer Head"
"Speaker"
    mm
    A
    A

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