Pigweed Live Notes: 2023-10-20

[Pigweed]

Hello! Here are the notes from the Pigweed Live that just ended.

Community discussion

• Jack (working with David Palchak) working on I3C initiator API.

  • I3C has additional complexity in initiator compared to I2C. Requires global view of all devices on bus and needs that info in advance.

  • I2C just needs address of device it's talking to. Been a lot of discussion on how to provide global info to I3C initiator.

  • Comes down to philosophical argument about centralizing hardware info. What's best way to accomplish that in Pigweed so that you're not coupling all hardware that might use I3C?

  • In Linux it's easy via Devicetree. I3C is first subsystem API that requires global view of otherwise unrelated pieces of hardware.

  • Possible to use product glue code to hand-carry info that API needs to product (e.g. board.c)? Wasn't scalable for Linux but could work for Pigweed.

    • General debate is whether each board would needs its own subclass.

  • Pigweed's HAL layer needs some reconsideration once async stuff lands. Should also consider whether Pigweed wants something like Devicetree.

  • I3C initiator has 2 roles: accepting registrations and then being the object to communicate with bus devices. David's leaning towards 2 classes for the 2 different roles.

  • Erik: A model that might work well for async future is to keep every device stateful and they get events when the bus is ready.

  • Logistics: we need someone to drive this through upstream Pigweed. 

Recently landed highlights (full changelog)

• pw_emu, a new module for emulator frontends

• UniquePtr (and broader discussion of upcoming allocator work?)

  • Looking for feedback on other allocation use cases. Leave comments through the SEED.

  • ETA for landing the SEED? Last call this week, wrapped up next week.

• SEEDS

  • 0105: Add nested tokens and tokenized args to pw_tokenizer and pw_log

  • 0109: Communication Buffers

  • 0111: Make Bazel Pigweed’s Primary Build System

  • 0112: Async Poll Model

• Kudzu, electronic badge that Pigweed team made for Maker Faire 2023

  • Source code is an example of complex Pigweed usage

  • Brought hardware to Maker Faire in wearable form factor

• New docs: Get started with Bazel guide, Facades and backends explainer, landing page for getting started docs

Active SEEDs

• 0103: pw_protobuf Object Model

• 0106: Project Template

• 0110: Memory Allocation Interfaces

• 0113: Modular Bazel C/C++ Toolchain API

  • Hoping to enter last call at start of next week

• 0114: Channels

  • Polishing up, will be ready for review later this week

• 0115: Sensors