baihengrui/esp32c3_usb_meter

How baihengrui/esp32c3_usb_meter works

This firmware turns an ESP32-C3 USB meter into a live measurement instrument: it initializes the hardware, samples an INA226/INA228, updates threshold timing and graph data, and presents readings and system state on the LCD. Separate FreeRTOS tasks handle button interaction, host commands, UI rendering, and queued offline recording. The documented product branches include settings, waveforms, threshold-triggered sessions, LittleFS export, and USB CDC data transfer. Main task wiring and storage behavior are sampled; several HAL/UI details are supported by the README, not inspected source excerpts.

Main entry points: main.cpp FreeRTOS tasks · hal_storage.cpp Recording service · hal_uart.cpp UART commands · globals.cpp Shared meter state

Components 22

Runtime and HAL

FreeRTOS tasks src/main.cpp
HAL application src/hal/hal.cpp
Shared meter state src/hal/globals.cpp
Persistent settings src/hal/hal_nvs.cpp

Measurement

INA acquisition src/hal/hal_ina.cpp
Threshold timing src/hal/hal_timer.cpp
Graph sampling src/hal/hal.cpp

Interaction and display

Button events src/hal/hal_button.cpp
UART commands src/hal/hal_uart.cpp
Settings menu src/hal/lcd_menu.cpp
Meter UI src/ui/ui.cpp
LCD control src/hal/hal_lcd.cpp
USB protocol hook src/hal/hal_protocol.cpp

Offline records

Recording service src/hal/hal_storage.cpp
Record queue src/hal/hal_storage.cpp
Session files src/hal/hal_storage.cpp

Other components

Meter operator
Host computer
INA226/228 sensor
Physical buttons
TFT display
LittleFS

Connections 33

Meter operator → Physical buttons: presses
Physical buttons → Button events: generates events
FreeRTOS tasks → HAL application: initializes system
FreeRTOS tasks → INA acquisition: runs acquisition task
FreeRTOS tasks → Threshold timing: updates thresholds
FreeRTOS tasks → Recording service: runs storage task
FreeRTOS tasks → Button events: polls buttons
FreeRTOS tasks → UART commands: polls commands
FreeRTOS tasks → Graph sampling: updates graph data
FreeRTOS tasks → Meter UI: runs app rendering
INA acquisition → INA226/228 sensor: reads measurements
INA acquisition → Shared meter state: updates readings
Threshold timing → Shared meter state: updates timing state
Graph sampling → Shared meter state: updates graph buffer
Button events → Settings menu: controls settings
Button events → Shared meter state: changes app state
UART commands → Shared meter state: updates settings
UART commands → Persistent settings: persists settings
UART commands → Host computer: sends CDC data
Host computer → UART commands: sends commands
UART commands → Recording service: requests record actions
Recording service → Record queue: receives samples
INA acquisition → Recording service: samples for recording
Recording service → Session files: writes sessions
Recording service → LittleFS: reads and writes
Recording service → Host computer: streams exports
Meter UI → Shared meter state: reads meter state
Meter UI → TFT display: renders screens
HAL application → LCD control: initializes display
LCD control → TFT display: controls display
Settings menu → Persistent settings: reads and writes
Threshold timing → Recording service: triggers recording
UART commands → USB protocol hook: delegates USB protocol

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Drawn by GitDiagram on September 28, 2026 from the repository's file tree, README and source files. Read as Markdown ·