MUSB

Musbmhdrc IP Registers and embassy-usb-driver Implementation.

This crate contains register information because some manufacturers modify register offsets or mask certain registers, making it challenging for peripheral access crates (PACs) to handle these uniformly.

Therefore, this crate includes built-in profiles. While standard, complete MUSB chip profiles exist, other chips are recommended to be supported by adding custom profiles.

How to Identify a MUSB IP?

• Registers start with POWER, FADDR (though not always at the beginning)
• Most registers are 8-bit (some manufacturers group them into 32-bit, but it's usually clear they're composed of 8-bit registers)
• Interrupt control and status registers are INTRRX(INTR_OUT), INTRTX(INTR_IN), INTRUSB
• An INDEX register exists, requiring setting before endpoint operations. EP0 registers are separate, other endpoints use TXCSRH, TXCSRL, RXCSRH, RXCSRL (or IN_CSR1, IN_CSR2, OUT_CSR1, OUT_CSR2)
• Compare with block-peri-std to confirm register similarity

Chips with musb IP:

Vendor		Chips (not fully listed)	IP
Texas Instruments		am335x,am1802, F2837xD, LM3S6911	musb**
allwinner	全志	F1C100S, F133	musb phy ip
SiFli	思澈	SF32LB52x	musb std*
beken	北科微 or 小博通	beken725x	musb std*
essemi	东软载波微	ES32F027x	musb std*
STC	姚永平	stc8, stc32, ai8051u	musb mini*
Puya	普冉	py32f071, py32f403	musb mini*

*: Not sure about the IP name

**: Further identification is needed

Usage

dependencies

When you don't use prebuild feature, you need to install:

cargo install --git https://github.com/embedded-drivers/yaml2pac --rev 0b96c69a30557214ceb16bd7429ab9ca1c52fc7e --locked

# On the Stable toolchain
rustup component add rustfmt
# On the Nightly toolchain
rustup component add rustfmt --toolchain nightly

Available Built-in Profiles

These built-in profiles are used via Cargo features (see below), with only one selectable:

builtin-py32f07x (contains base_address) builtin-py32f403 (contains base_address) builtin-std-full

These profiles include register descriptions, number of endpoints, etc. Base address is optional. If left blank, it reads from the MUSB_BASE_ADDRESS environment variable. If this value is in hexadecimal, it must start with 0x.

Prebuild

Pre-generated Rust register code is available in src/prebuild, eliminating the need to rerun build scripts generating these contents.

Integrate this crate into a HAL crate

Example: py32-hal/src/usb.rs · py32-rs/py32-hal

Profiles & Registers

Each manufacturer's SVD or manual exhibits significant register name variations, despite functional consistency. This crate uses standard MUSB register names.

The crate describes registers using YAML, with these register description files manually maintained. It then leverages chiptool and yaml2pac to generate register operation functions. These operations can be found in the build.rs file.

Available Replacements

These replacements are automatically generated from profile contents and can be used in register description YAML files.

ENDPOINT_COUNT

profile.endpoint_count

FIFO_REG_BIT_SIZE

profile.reg_bit_size.fifo

Note: This does not change the offset.

INTR_REG_BIT_SIZE

profile.reg_bit_size.intr

Note: This does not change the offset.

Contribute

If you have any questions or uncertainties, feel free to create an Issue or start a Discussion.

TODOs:

• Support SiFli SF32BL52
• Other Chips
• better support for standard musb
• host mode