STM32-pio-libs is a collection of reusable libraries for STM32Cube HAL and PlatformIO based STM32 projects. Packages are published on registry.platformio.org and can be installed with pio pkg.

This organization exists to provide clean, reusable, and well-documented STM32 libraries that can be dropped into application code without unnecessary friction.

The goals are:

• keep public APIs small and practical
• move drivers toward hardware-agnostic callback-based designs where it makes sense
• provide examples that show the intended integration pattern
• improve package-level documentation and repository consistency

Rather than treating each driver as a one-off code dump, the work here is to gradually move the libraries toward a more consistent and maintainable structure.

• W25Q64-flash Hardware-agnostic driver for the W25Q64 8 MB SPI NOR flash chip. Callback-based SPI transport with no HAL dependency in the library itself. Covers read, write (with automatic page splitting), sector/block/chip erase, and deep power-down.

• W25Q64-lfs LittleFS block device adapter for W25Q64-flash. Single-call setup via W25Q_LFS_BuildConfig, static working buffers, no heap allocation. Pass the resulting lfs_config directly to lfs_mount.

• littlefs Upstream LittleFS v2.11.3 repackaged as a PlatformIO library. Pulled in automatically as a transitive dependency of W25Q64-lfs.

• SSD1306 Driver for SSD1306 OLED displays over I2C or SPI. Callback-based transport, full-screen and partial-region bitmap updates, and display control APIs (contrast, invert, power).

• gfx-mono Lightweight monochrome graphics library for 1 bpp framebuffers. Pixels, rectangles, bitmap drawing, nearest-neighbor bitmap scaling, and scalable A–Z / 0–9 glyphs. A flush callback decouples it from any specific display IC — pairs naturally with SSD1306.

• I2C-LCD Driver for HD44780-compatible character LCD modules connected through an I2C backpack (typically PCF8574). Callback-based I2C write and delay hooks. Cursor positioning, text output, custom CGRAM characters, backlight, and display controls.

• DS1302-RTC Driver for the DS1302 real-time clock IC using GPIO bit-bang over CE/IO/SCLK. Individual and burst time/date accessors, 12/24-hour mode switching, and 31-byte battery-backed RAM read/write.

• NEO-6M TinyGPS-style NMEA parser and interrupt-driven UART receive helper for the u-blox NEO-6M GPS module. Decodes RMC and GGA sentences: location, UTC date/time, speed, course, altitude, satellite count, HDOP, and fix quality.

• stm32-Delay Microsecond and millisecond delay functions for STM32Cube HAL projects.

• stm32f411-blackpill-base Minimal PlatformIO project template for the STM32F411CE BlackPill board. Clock configured at 100 MHz over HSE with PLL, UART1 printf/scanf via syscall stubs. Use as a starting point for new BlackPill projects.

• F411-W25Q64-lfs-cli Interactive filesystem shell for the STM32F411CE BlackPill backed by a W25Q64 flash chip running LittleFS. Shell commands: ls, lsr, cat, touch, mkdir, rm, cd, pwd, info. Includes pcfstool, a Linux companion tool for transferring files to and from the board over UART.

These libraries are intended for developers working on:

• STM32Cube HAL projects
• PlatformIO-based STM32 firmware
• small and medium embedded applications that need straightforward reusable components

This is a practical, code-first organization. Bug reports, cleanup patches, example improvements, portability fixes, and documentation updates are all useful contributions.