Project Specification
Project Overview
Beginner-friendly prototype carrier for an original ESP32-WROOM-32 DevKitC-style board and ready-made sensor modules. Status: Schematic Review.
Intended Use
Bench prototype powered from a dedicated 5 V / 3 A USB-C adapter while a laptop may simultaneously connect to the ESP32 development board's own USB programming port.
What the Device Should Do
- Power all modules safely without backfeeding either USB source.
- Read two independent radar UART streams, I2S audio, MQ-2 analog level, and DHT11 data.
- Provide an optional future XIAO software-UART link.
Main Features
USB-C sink CC resistors, 3 A resettable fuse, 5 V TVS, bulk/local bypass, power LED, series Schottky isolation, dedicated 3 A/2.2 MHz radar buck regulator, through-hole module headers.
System Architecture
See the Block Diagram project file.
Hardware Subsystems
- USB-C power and protection
- ESP32 DevKit carrier interface
- 3.3 V radar power
- Dual radar UART headers
- INMP441 I2S header
- MQ-2 protected ADC input
- DHT11 and optional XIAO headers
Interfaces and Connections
See Design Notes for the final GPIO and connector maps.
Power and Runtime Expectations
No battery. Use a USB-C source that explicitly supports 5 V / 3 A. The design does not implement USB-PD or electronically inspect advertised Type-C current.
Power Tree and Power Budget
Worst-case protected-5 V allocation is 1.81 A. The two radars dominate at 1.2 A on 3.3 V. See Design Notes for calculations.
Manufacturing and Assembly Expectations
Prototype intent. Headers and most passives are chosen for beginner handling; the TPS62823 regulator is a fine-pitch QFN and should be assembled by a PCB assembler or replaced in a future revision by a verified 3.3 V/3 A module if fully hand-soldered assembly is mandatory.
Firmware-Relevant Hardware Requirements
Arduino/PlatformIO starter is provided. UART examples are raw pass-through/basic reads and do not invent proprietary radar protocols.
Physical Design Expectations
Accessible edge connectors; final dimensions deferred to layout. Confirm exact ESP32 board mechanics before placement.
Important Design Decisions
- Dedicated buck powers the radars because the DevKit 3.3 V regulator budget is undocumented and inadequate to assume for 1.2 A load.
- UART0 stays reserved; hardware UART1/2 serve radars.
- MQ-2 uses GPIO34 ADC1 through a 2:3 divider.
- DHT11 and INMP441 use the lightly loaded DevKit 3.3 V rail.
Assumptions
38-pin ESP32-DevKitC-32UE-compatible board; module cables adapt to labeled 2.54 mm headers.
Change Notes
Completed schematic architecture, sourced electrical limits, power budget, GPIO mapping, and firmware starter documentation.