Mastodawn

One of my favorite features of the Baochip-1x is the BIO. It's an I/O coprocessor that is based on the PicoRV32, with custom register extensions to allow direct access to GPIOs from the ISA.

Read more about the BIO at this blog post: https://www.bunniestudios.com/blog/2026/bio-the-bao-i-o-coprocessor/ I go in-depth into the architecture and its trade-offs relative to the PIO, and conclude by working through a couple of coding examples.

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Brian Swetland

@bunnie I really like using the top half of the register file for block-specific functionality, which ends up being doubly clever due to RV32E already defining a standardized ABI using only the bottom half (if you're going to re-use existing higher level tool chains, etc). Nice design.