Dependencies between libraries

DEPENDS · TRANSITIVE · LDF · HIDDEN CODE

A library you pull in may need libraries of its own. PlatformIO arranges that without reporting it: code appears in the build that is named in no platformio.ini at all. This chapter makes that layer visible — six libraries that are declared nowhere and are compiled in regardless, and a handful of dependencies requested not by a library's driver but by its example sketches.

[!NOTE] Source. This page is the only one in the repo that does not rest solely on the MeshCore source code. The dependencies come from the library.properties and library.json files of the upstream repositories, fetched from raw.githubusercontent.com on 28 July 2026 with tools/library-overview.py. The declarations themselves were verified against MeshCore v1.16.0, commit 03b6ef4, 28 July 2026 — platformio.ini and the seventy-nine variants/*/platformio.ini.

How PlatformIO finds dependencies

Two mechanisms work side by side.

The first is the library's own metadata. An Arduino library has a library.properties with a depends= line, a PlatformIO library a library.json with a "dependencies" key. Whatever is there is fetched as if it had been written in lib_deps.

The second is the Library Dependency Finder. The LDF scans the source for #include lines and looks for matching libraries, even when nobody declared them. In its default chain mode it looks at the files that are actually compiled. The result is that a build can contain more than what you wrote down, and that you see nothing of it as long as everything compiles.

The six libraries declared nowhere

These six appear in none of the eighty platformio.ini files and still end up in the build:

Library	Arrives via	Scope
bblanchon/ArduinoJson	electroniccats/CayenneLPP	all 507 builds
Adafruit Unified Sensor	BME280, BMP280, BMP085, BME680, AHTX0, SHTC3, LIS3DH, SHT4x	sensor builds
Sensirion Core	Sensirion I2C SHT4x	sensor builds
ESP32Async/AsyncTCP	ESPAsyncWebServer	ESP32 with WiFi OTA
Adafruit seesaw Library	Adafruit ST7735 and ST7789	six TFT variants
SD	Adafruit ST7735 and ST7789	six TFT variants

The first row is the most striking. CayenneLPP sits in [arduino_base] and therefore applies to all 507 build targets; its library.json names bblanchon/ArduinoJson as a dependency. That puts a JSON parser in every MeshCore build, including that of a repeater that never sees any JSON.

Adafruit Unified Sensor is Adafruit's shared sensor abstraction; eight of the fifteen sensor libraries in [sensor_base] ask for it. SD and Adafruit seesaw Library arrive with the ST7735/ST7789 driver, including on boards without a card reader.

The full depends= table

Per declared library, whatever its own metadata states. Generated with tools/library-overview.py; an empty cell means the library declares no dependencies.

Generated with tools/library-overview.py against commit 03b6ef4.

Library	Depends on	Source
Adafruit AHTX0	Adafruit Unified Sensor, Adafruit BusIO, Adafruit SH110X	library.properties
Adafruit BME280 Library	Adafruit Unified Sensor, Adafruit BusIO	library.properties
Adafruit BME680 Library	Adafruit Unified Sensor, Adafruit GFX Library, Adafruit SSD1306, Adafruit BusIO	library.properties
Adafruit BMP085 Library	Adafruit Unified Sensor, Adafruit BusIO	library.properties
Adafruit BMP280 Library	Adafruit Unified Sensor, Adafruit BusIO	library.properties
Adafruit BusIO	—	library.properties
Adafruit EPD	Adafruit GFX Library	library.properties
Adafruit GFX Library	Adafruit BusIO	library.properties
Adafruit INA219	Adafruit NeoPixel, Adafruit GFX Library, Adafruit SSD1306, Adafruit BusIO	library.properties
Adafruit INA260 Library	Adafruit BusIO, Adafruit NeoPixel	library.properties
Adafruit INA3221 Library	Adafruit BusIO	library.properties
Adafruit LIS3DH	Adafruit Unified Sensor, Adafruit BusIO	library.properties
Adafruit MLX90614 Library	Adafruit BusIO	library.properties
Adafruit NeoPixel	—	library.properties
Adafruit SH110X	Adafruit GFX Library, Adafruit BusIO	library.properties
Adafruit SHT4x Library	Adafruit BusIO, Adafruit Unified Sensor, Adafruit SH110X, Adafruit SSD1306	library.properties
Adafruit SHTC3 Library	Adafruit BusIO, Adafruit Unified Sensor	library.properties
Adafruit SSD1306	Adafruit GFX Library	library.properties
Adafruit ST7735 and ST7789 Library	Adafruit GFX Library, Adafruit seesaw Library, SD	library.properties
Adafruit_VL53L0X	Adafruit SSD1306, Adafruit GFX Library	library.properties
Arduino_LPS22HB	—	library.properties
base64	—	library.properties
BME280	—	library.properties
BSEC	BME68x Sensor library	library.properties
CayenneLPP	bblanchon/ArduinoJson	library.json
CRC32	—	library.properties
Crypto	—	library.json
ESPAsyncWebServer	AsyncTCP, ESPAsyncTCP, Hash, RPAsyncTCP	library.json
googletest	not retrieved — no Arduino metadata; the registry package carries no library.json	—
GxEPD2	Adafruit GFX Library	library.properties
INA226	—	library.properties
LovyanGFX	—	library.properties
Melopero RV3028	not retrieved — repository not found under the expected name on GitHub	—
MicroNMEA	—	library.properties
NonBlockingRTTTL	—	library.properties
PCA9557-arduino	—	library.properties
RadioLib	—	library.properties
RTClib	Adafruit BusIO	library.properties
Sensirion I2C SHT4x	Sensirion Core	library.properties
SparkFun u-blox GNSS Arduino Library	—	library.properties
SPI	not retrieved — framework library, ships with the platform package	—
SubGhz	not retrieved — framework library, ships with framework-arduinoststm32	—
U8g2	—	library.properties
Wire	not retrieved — framework library, ships with the platform package	—
XPowersLib	—	library.properties

Dependencies of example sketches

A depends= says nothing about which part of the library needs something. For five Adafruit libraries the declaration applies to the examples/ directory, not to the driver:

Library	Declares	Needed for
Adafruit INA219	NeoPixel, GFX, SSD1306, BusIO	example sketches
Adafruit INA260	BusIO, NeoPixel	example sketches
Adafruit_VL53L0X	SSD1306, GFX	example sketches
Adafruit BME680	Unified Sensor, GFX, SSD1306, BusIO	example sketches
Adafruit AHTX0	Unified Sensor, BusIO, SH110X	example sketches

The consequence is concrete: switch on [sensor_base] and a current meter pulls in two display libraries. The -w flag in [arduino_base] suppresses all compiler warnings, so no signal about that ever appears:

platformio.ini r.27

build_flags = -w -DNDEBUG -DRADIOLIB_STATIC_ONLY=1 -DRADIOLIB_GODMODE=1

Manually pinned transitive dependencies

adafruit/Adafruit GFX Library @ ^1.12.1 is declared explicitly in lib_deps in eight variants, while Adafruit SSD1306 already brings it in through its own depends=. adafruit/Adafruit BusIO @ ^1.17.2 is declared explicitly in one:

variants/sensecap_indicator-espnow/platformio.ini r.31-33

lib_deps=${esp32_base.lib_deps}
  adafruit/Adafruit BusIO @ ^1.17.2
  lovyan03/LovyanGFX @ ^1.2.7

That is not duplication. A transitive dependency has no version range of its own in the build; declaring it anyway pins the version of a library you never use directly.

Not verified

The dependencies of melopero/Melopero RV3028 could not be retrieved: the library.properties was not found and the repository is not on GitHub under the expected name. That row stays empty, with the reason stated. google/googletest has no Arduino metadata; the registry package carries no library.json. The three framework libraries SPI, Wire and SubGhz have no upstream metadata by definition.

Three declarations without a findable include

[!NOTE] Three libraries are declared but no #include of their headers can be found anywhere in src/, examples/, variants/ or arch/. They are adafruit/Adafruit EPD @ 4.6.1 (variants/mesh_pocket/platformio.ini r.30) and adafruit/Adafruit LIS3DH @ ^1.2.4 plus adafruit/Adafruit SHT4x Library @ ^1.0.4 (variants/wio_wm1110/platformio.ini r.36-37). The search ran on the header names Adafruit_EPD, Adafruit_LIS3DH and Adafruit_SHT4x across all files with extension .h, .hpp, .c, .cpp and .ino. The SHT4x sensor is driven in the firmware by SensirionI2cSht4x (src/helpers/sensors/EnvironmentSensorManager.cpp r.90-91), not by the Adafruit library. This is an observation; no conclusion is drawn from it here.

Sources

• platformio.ini
• variants/mesh_pocket/platformio.ini
• variants/wio_wm1110/platformio.ini
• variants/sensecap_indicator-espnow/platformio.ini
• src/helpers/sensors/EnvironmentSensorManager.cpp
• PlatformIO — Library Dependency Finder

Translated from Dutch by Anthropic Claude