# tinyboot-ch32-hal
Part of the [tinyboot](https://github.com/OpenServoCore/tinyboot) project — see the main README to get started.
Minimal hardware abstraction layer for tinyboot on CH32 microcontrollers. This is not a general-purpose HAL — it provides only what the bootloader needs, optimized for code size.
## Modules
| `flash` | Flash read/write/erase, option byte access |
| `gpio` | Pin configuration (input, output, alternate function) |
| `usart` | UART transmit/receive with embedded-io traits |
| `rcc` | Clock configuration and peripheral reset |
| `afio` | Alternate function I/O and pin remapping |
| `pfic` | Interrupt controller and system reset |
| `iwdg` | Independent watchdog timer feed |
| `boot_request` | RAM-based boot request signaling (user-flash only) |
## Code generation
`build.rs` reads chip metadata from `ch32-metapac` and generates:
- **`Pin` enum** — all GPIO pins with bit-packed discriminants for table-free port/pin extraction
- **`UsartMapping` enum** — all USART remap configurations with TX/RX pin and register accessors
This keeps the source chip-agnostic while producing zero-overhead accessors.
## Features
| `ch32v003f4p6` | CH32V003F4P6 chip variant (default) |
| `system-flash` | Bootloader runs from system flash (uses BOOT_MODE register for boot requests) |
## Notes
- `critical-section` is included but implemented as a no-op — the bootloader runs with interrupts disabled.
- All modules use PAC register access directly for minimal code size.