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Project Specification
Project Overview
Compact ESP32-C3 Super Mini carrier for battery-powered audio, sensing, touch, and PWM LED control. Status: Draft implementation.
Intended Use
Prototype controller powered from USB-C or a protected 1S Li-ion cell, with external peripherals attached by soldered wires.
What the Device Should Do
  • Charge a 1S Li-ion battery at up to at least 2 A with power-path/load sharing.
  • Generate a regulated 5 V system rail from the battery.
  • Run an ESP32-C3 Super Mini development board from 5 V.
  • Drive a 4 ohm speaker using a MAX98357A I2S amplifier.
  • Interface to an external INMP441 I2S microphone module.
  • Read a capacitive touch electrode and external LDR.
  • PWM-switch an external 1.5 W LED.
Main Features
  • USB-C 5 V input with CC resistors and protection.
  • Protected 1S Li-ion connection.
  • 5 V high-current rail and 3.3 V peripheral rail.
  • I2S speaker amplifier and external digital microphone pads.
  • TTP223 touch input.
  • LDR ADC divider and MOSFET LED output.
  • Spare GPIO solder pads.
System Architecture
Diagram



  
    
  
  
    
  


























USB-C node_5V
2A Charger and Power Path
1S Protected Li-ion
5V Boost
ESP32-C3 Super Mini
MAX98357A
External 1.5W LED
3.3V LDO
TTP223
External INMP441
External LDR Divider
Hardware Subsystems
  • Power: USB-C sink, input protection, 2 A charger with power path, battery protection interface, 5 V boost, 3.3 V LDO.
  • Compute: user-supplied 22.5 mm x 18 mm generic ESP32-C3 Super Mini solder-on carrier.
  • Audio: MAX98357A mono amplifier to 4 ohm speaker pads; external INMP441 module pads.
  • Inputs: TTP223 external electrode and LDR ADC divider.
  • Output: external 1.5 W LED pads with low-side logic MOSFET PWM.
Interfaces and Connections
All external wire pads are located along one PCB edge: battery, speaker, INMP441, LED, LDR, touch electrode, and spare GPIO.
Power and Runtime Expectations
Battery capacity and runtime are not specified. Design for high transient current from audio, Wi-Fi, LED, and the 5 V boost converter.
Power Tree and Power Budget

Table

RailLoadPeak assumption
5 VESP32-C3 Super Mini0.50 A
5 VMAX98357A / 4 ohm speaker0.80 A
5 VExternal 1.5 W LED0.30 A
5 VMargin and 3.3 V conversion0.20 A
5 V total1.80 A
At a 3.0 V depleted-cell condition and 85% boost efficiency, estimated battery current is about 3.53 A. The battery, protection path, inductor, switching converter, and copper must tolerate at least 4 A peak with margin. USB-C source current must be detected/limited appropriately; a Type-C receptacle does not guarantee 2 A from every source.
Manufacturing and Assembly Expectations
Compact 2-layer PCB, SMD assembly, minimum practical component count, JLCPCB-available parts preferred, no headers/connectors/screw terminals except the USB-C receptacle and solder pads.
Firmware-Relevant Hardware Requirements
Avoid ESP32-C3 GPIO8 and GPIO9 boot-strap conflicts and GPIO18/GPIO19 native USB functions. Assign I2S, touch, PWM, ADC, and spare GPIOs to pins physically available on the selected Super Mini carrier.
Physical Design Expectations
  • ESP32 carrier dimensions: 22.5 mm x 18 mm.
  • Carrier antenna end must face a board edge with copper/component keepout beneath and ahead of the antenna.
  • Ground plane except antenna keepout.
  • Separate switching-current loops from audio and microphone wiring.
  • Wide battery and 5 V copper.
Important Design Decisions
  • External LED is represented by two solder pads; current limiting is on the carrier board.
  • INMP441 is an external module connected by solder pads.
  • Speaker impedance is 4 ohms.
  • The ESP32-C3 is a complete user-supplied development board, not a bare IC/module.
Assumptions
  • Common 16-pin ESP32-C3 Super Mini pin arrangement will be used only if a matching verified footprint/pinout is available; otherwise implementation must stop rather than inventing geometry.
  • External Li-ion cell must support the calculated discharge current.
  • LED current target is approximately 300 mA for a nominal 1.5 W load from 5 V; final resistor value depends on actual LED forward voltage.
Change Notes
  • Added measured ESP32 carrier size, 4 ohm speaker, external INMP441 module, and two-pad external LED requirements.

  • Project Overview

  • Intended Use

  • What the Device Should Do

  • Main Features

  • System Architecture

  • Hardware Subsystems

  • Interfaces and Connections

  • Power and Runtime Expectations

  • Power Tree and Power Budget

  • Manufacturing and Assembly Expectations

  • Firmware-Relevant Hardware Requirements

  • Physical Design Expectations

  • Important Design Decisions

  • Assumptions

  • Change Notes