pw_hal#

Experimental

Pigweed HAL (pw_hal) is a unified Hardware Abstraction Layer providing clean, modern C++ interfaces and driver abstractions for microcontroller peripherals.

It builds upon the previous efforts in pw_i2c, pw_spi, etc., by unifying HAL design across peripherals, adding native support for pw_async2, and focusing on enabling agentic development of low-level drivers in order to speed up hardware bring-up and broaden support across many silicon vendors.

Dashboard#

The dashboard below tracks the current status of Pigweed HAL peripheral APIs and driver implementations across roadmap phases.

Peripheral Domain	Investigation	Prototype	API Definition	First Platform
GPIO: Pinmux
GPIO: Digital IO
UART: Buffered	✔	✔	✔	⛏
UART: Zero Copy	✔	⛏
I2C: Initiator	✔	✔	⛏	⏱
I2C: Responder	⏱
I3C: Controller
I3C: Target
SPI: Controller	⛏
SPI: Target
ADC
DAC
Timer
PWM

Note

✔ - Phase completed.
⛏ - Work is actively underway for this phase.
⏱ - Work is planned but not yet started.
(blank) - Not yet started or planned.

Roadmap phases#

Investigation: Researching requirements, hardware peripheral capabilities, and cross-platform abstraction patterns.
Prototype: Developing experimental interfaces, proof-of-concept drivers, and test harnesses.
API Definition: Standardizing and reviewing abstract driver and controller interfaces in Pigweed HAL.
First Platform: Implementing and validating a complete driver on an initial hardware target with automated testing.
Multiple Platforms: Extending verified driver implementations across multiple distinct silicon architectures and vendor SDKs.

Peripherals under consideration#

These peripherals require additional investigation before including them as part of the planned pw_hal interface.

Clock Tree
Power Tree
Flash / EEPROM / NVM
QSPI
xSPI / mSPI
DMA
Display
Graphics Acceleration
I2S
Watchdog Timer