v0.7.2

Changed

• Firmware: frames to the host are queued, not written in place. firmware/common/tx.c encodes each
  frame into one of two rings (one for the USB side, one for the receive side) and feeds the UART
  from them; hal_uart_write is replaced by hal_uart_tx_start, hal_uart_tx_busy and
  hal_uart_tx_wait_done. On the RP2040 and RP2350 the UART output is a DMA channel and the
  critical section around every write is gone: before, an EP_OUT frame, an event or a control data
  stage written by the USB core spun on the UART byte by byte with interrupts off on that core, so the
  target's IN transfers waited for it. The other ports send from the CPU inside hal_uart_tx_start as
  before. Each port's mimusb_limits.h states MIMUSB_TX_RING_BYTES and MIMUSB_TX_RX_RING_BYTES
  (the build stops when they are missing; tests missing_*_limit). The ring replaces the 2 KiB
  long-frame buffer of the USB side.
• Firmware: an ASK rule on a host-to-device request with a data stage no longer stops the USB side while
  the host decides. The vendor callback of the data stage returns at once and the board keeps the
  status stage the stack asks for until the verdict is in (mimusb_control_hold_status); reports on
  the other endpoints go out meanwhile. mimusb_control_set_single_context is gone, since nothing
  waits any more. The wire protocol is unchanged.
• Firmware: the queue's lock is released with an atomic exchange, not a store. On the RP2040 (Cortex-M0+) the
  exchange runs under a hardware spinlock and a plain store does not, so a release landing inside the other
  core's exchange was overwritten and the lock stayed taken (the board stopped answering).

Added

• firmware/tests/test_tx.c: the frame queue against a UART that stays busy (ring wrap, frames of every
  length, two producers in order, a full ring, the rate change after the queue, a producer that does not
  wait for the line).
• Tests of the held status stage in firmware/tests/test_core.c: refused, accepted, no verdict in time,
  and voided by a new setup packet.

---

Firmware Binary Third-Party Notices

The host library (libmimusb) is licensed under the MIT License and has no third-party runtime library dependencies.

Prebuilt microcontroller firmware images (mimusb_firmware-*) incorporate third-party SDK and USB stack components under permissive licenses:

Firmware asset	Third-party components & licenses
mimusb_firmware-rp2040-*, mimusb_firmware-rp2350-*	TinyUSB 0.18.0 (MIT), Raspberry Pi Pico SDK 2.2.0 (BSD-3-Clause, Copyright (c) 2020 Raspberry Pi (Trading) Ltd.), Arm CMSIS Core (Apache-2.0), Newlib C runtime
mimusb_firmware-nrf52840-*	TinyUSB 0.18.0 (MIT), Nordic Semiconductor nrfx (BSD-3-Clause, Copyright (c) 2017-2024 Nordic Semiconductor ASA), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-stm32f4-*	TinyUSB 0.18.0 (MIT), STMicroelectronics cmsis_device_f4 & stm32f4xx_hal_driver (BSD-3-Clause / Apache-2.0, Copyright (c) 2016-2019 STMicroelectronics), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-esp32s3-*	TinyUSB 0.18.0 (MIT), Espressif ESP-IDF v5.4.2 (Apache-2.0, Copyright 2015-2025 Espressif Systems), Amazon FreeRTOS Kernel (MIT), Newlib C runtime

Complete copyright notices, license texts, and warranty disclaimers for all firmware binaries are provided in the release asset mimusb_firmware-THIRD_PARTY_NOTICES-0.7.2.txt and in THIRD_PARTY_NOTICES.md / NOTICE.

v0.7.1

The API has one shape for every kind of function: a factory makes a Spec, mimusb_node_open opens any
Spec at a placement, and control rules are the one way a class talks on endpoint 0, for HID and for
any class that comes after it. The wire protocol and the firmware are unchanged apart from the version
they report (a board must run firmware of the same minor version, 0.7).

Added

• mimusb_spec_create_cdc_acm and mimusb_cdc_acm_options: a CDC-ACM function as a Spec. The library
  writes the two interfaces, the class descriptors, the Interface Association descriptor and the
  three rules (SET_LINE_CODING, GET_LINE_CODING, SET_CONTROL_LINE_STATE); the data is the
  program's. Roles MIMUSB_ROLE_CDC_NOTIFY, _CDC_DATA_IN, _CDC_DATA_OUT; kind
  MIMUSB_PROFILE_CDC_ACM. src/classes/cdc_acm.cpp is where a class without a state lives: it only
  makes interfaces and rules at the placement and opens them as any interfaces are.
• mimusb_node_placement.extra_rules and extra_rule_count: control rules of the caller's own for a
  Node of any Spec (a HID profile too), tried before the rules the Spec brings. A request is answered by
  the first rule that matches, so a rule of the caller's can take over one the library would answer.
• mimusb_node_find_rule and mimusb_rule_slot (MIMUSB_RULE_SLOT_CDC_LINE_CODING): a rule a Spec
  names is found by name, not by its place among the Node's rules.
• mimusb_spec_interface_count and mimusb_spec_rule_cost: how many interface numbers a Spec takes
  and what it adds to the board's rule memory.
• mimusb_target_limits (mimusb_device_config.target): what the target machine limits, whatever the
  function. Its one member is linux_hid.
• docs/API.md: Kinds of Spec, one table of every factory with its interfaces, roles, rules and
  state.

Changed

• mimusb_spec_create_raw is mimusb_spec_create_hid, and mimusb_raw_options, mimusb_raw_report,
  mimusb_raw_options_init, mimusb_raw_submit and MIMUSB_PROFILE_RAW are
  mimusb_hid_options, mimusb_hid_report, mimusb_hid_options_init, mimusb_hid_submit and
  MIMUSB_PROFILE_HID: it was always a HID Spec, with a report descriptor of the caller's own. The
  fields of its errors begin with hid. instead of raw.. "Raw" now means only a Device given as
  bytes (mimusb_device_set_descriptors).
• MIMUSB_HID_ROLE_IN and _OUT are MIMUSB_ROLE_HID_IN and _HID_OUT: a role is named for the kind
  of Spec that has it.
• mimusb_transport_options.linux_hid is mimusb_device_config.target.linux_hid, and it is required
  when a Node of a HID Spec is opened (MIMUSB_ERR_UNSET_FIELD otherwise), not when the Device is
  opened: a Device that opens only CDC-ACM or interfaces Nodes leaves it 0.
• mimusb_node_placement is 56 bytes (was 40) and mimusb_device_config has target after
  transport; the layout golden file and the generated bindings follow. The control rules of every
  Node, not only those of a mimusb_spec_create_interfaces Spec, come first in the table the board
  holds, before those the library writes for the HID profiles and those of the Device.
• mimusb_node_set_rule_data numbers a Node's rules as its extra_rules first, then the rules its
  Spec brings.
• Inside the library, HID is a class like any other: every class is a FunctionClass
  (src/classes/function_class.hpp) that builds a Node's interfaces and rules at its placement, lays
  out its Nodes at each commit and hears the requests its rules take. The device layer (src/api)
  knows no class; HID's report state is the runtime of a HID Node (HidNode), and the HID code lives
  in src/classes/hid/, one file per profile for the Spec factories (spec_*.cpp) and the state
  machines (state_*.cpp). The rules a class answers live (HID's GET_IDLE, GET_PROTOCOL) are
  marked as such instead of being known by their kind. No change to the API, the ABI or the wire.

Removed

• mimusb_hid_descriptor_bytes and mimusb_hid_descriptor_rule: a HID interface of the caller's own is
  a mimusb_spec_create_hid Spec; for one whose descriptor must not be checked the 9 bytes and the rule
  are written out in a mimusb_spec_create_interfaces Spec (examples/c/hid_interface.c).
• mimusb_cdc_acm_descriptors, mimusb_cdc_acm_descriptors_make and mimusb_cdc_acm_rules:
  replaced by mimusb_spec_create_cdc_acm.

---

Firmware Binary Third-Party Notices

The host library (libmimusb) is licensed under the MIT License and has no third-party runtime library dependencies.

Prebuilt microcontroller firmware images (mimusb_firmware-*) incorporate third-party SDK and USB stack components under permissive licenses:

Firmware asset	Third-party components & licenses
mimusb_firmware-rp2040-*, mimusb_firmware-rp2350-*	TinyUSB 0.18.0 (MIT), Raspberry Pi Pico SDK 2.2.0 (BSD-3-Clause, Copyright (c) 2020 Raspberry Pi (Trading) Ltd.), Arm CMSIS Core (Apache-2.0), Newlib C runtime
mimusb_firmware-nrf52840-*	TinyUSB 0.18.0 (MIT), Nordic Semiconductor nrfx (BSD-3-Clause, Copyright (c) 2017-2024 Nordic Semiconductor ASA), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-stm32f4-*	TinyUSB 0.18.0 (MIT), STMicroelectronics cmsis_device_f4 & stm32f4xx_hal_driver (BSD-3-Clause / Apache-2.0, Copyright (c) 2016-2019 STMicroelectronics), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-esp32s3-*	TinyUSB 0.18.0 (MIT), Espressif ESP-IDF v5.4.2 (Apache-2.0, Copyright 2015-2025 Espressif Systems), Amazon FreeRTOS Kernel (MIT), Newlib C runtime

Complete copyright notices, license texts, and warranty disclaimers for all firmware binaries are provided in the release asset mimusb_firmware-THIRD_PARTY_NOTICES-0.7.1.txt and in THIRD_PARTY_NOTICES.md / NOTICE.

v0.6.1

The firmware's RAM limits are the port's, and none has a default. The wire protocol and the C ABI
are unchanged; the board reports its limits in the PONG as before, so a host library reads the larger
numbers without change. A board has to be flashed with this firmware to have them.

Changed

• firmware/common/config.h no longer defines MIMUSB_MAX_INTERFACES, MIMUSB_MAX_CONFIG_BYTES,
  MIMUSB_MAX_BOS_BYTES, MIMUSB_MAX_STRINGS, MIMUSB_MAX_STRING_BYTES, MIMUSB_MAX_REPORT_BYTES,
  MIMUSB_CONTROL_DATA_MAX, MIMUSB_EP_POOL_SLOTS, MIMUSB_CONTROL_RULES, MIMUSB_ANSWER_BYTES or
  MIMUSB_LAST_SENT_SLOTS when a port leaves them out. Every port states all of them in its own
  mimusb_limits.h (RP2040, RP2350, nRF52840, four STM32F4 RAM classes, ESP32-S3), and a build without
  the file or with one limit missing stops with a message that names it (firmware/tests:
  missing_*_limit).
• The limits are raised to what each chip's RAM holds. Largest on the RP2350 and the nRF52840: a
  configuration descriptor of 8192 bytes (was 1024), 128 strings (24), 254 control rules (160), 32768
  bytes of answer memory (4096), a control data stage of 4088 bytes (1024), a BOS of 1024 bytes (256).
  The RP2040: 4096, 64, 254, 16384, 2048, 512. The STM32F401, with 64 kB of RAM, has 2048, 24, 96, 4096,
  1024, 256: its control rules go down from 160 to 96 (the other figures are as before or larger), so
  that 6 KiB of its RAM stay free (the former figures left about 5 KiB, measured on the F411 build). The
  figures are in docs/LIMITS.md; the protocol bounds them (254
  rules, a 4088-byte control data stage, 16-bit lengths).
• MIMUSB_MAX_STRING_BYTES is its own limit and no longer MIMUSB_MAX_STRINGS strings of 254 bytes: a
  store of fewer long strings than the count is refused with NAK_OVERFLOW when it is full.

Added

• firmware/tools/check_ram.py and check_ram.cmake: after the link, the build prints the RAM the image
  takes (data + bss, plus a stack outside them) and stops when fewer than the reserve the port states
  are left. Every firmware build here runs it; the ESP-IDF build does not (ESP-IDF has its own memory
  summary).
• firmware/tests/limits_probe.c and the tests missing_mimusb_limits_h and missing_*_limit.

Verified

Hardware-verified on 2026-11-13 for the parts listed here. Built: RP2040, RP2350 (Pico SDK), nRF52840
(pca10056), STM32F401, F411, F439 and F412 boards (TinyUSB BSP); not built: the ESP32-S3 (no ESP-IDF
here). ctest of the host library (23 tests, mimusb.sim-* against the real ports' limits) and of
firmware/tests (30) pass.

Run on a board: a Raspberry Pi Pico (RP2040) with a Prolific PL2303 adapter (7,812,500 baud), the target
the same Linux machine (Linux 7.2.11, a VMware guest, both USB devices passed through). The board ran
0.6.0, was restarted with mimusb_device_enter_bootloader, written with this release's UF2 image, and
reported firmware 0.6.1 and the new limits (configuration 4096, strings 64, rules 254, answer memory
16384, control data 2048, BOS 512, queue slots 72) with no CRC, framing or overrun error. hw_bulk wait|newest|oldest, hw_control_rules, hw_composite, hw_bytes bytes|bos, hw_iso, hw_cdc,
hw_msc, hw_ecm, hw_dfu, hw_printer and hw_midi all passed. Not run: a second machine as the
target, Windows or macOS, the RP2350 and the other boards (their limits are built, not run), the
mimusb_verify_* programs.

---

Firmware Binary Third-Party Notices

The host library (libmimusb) is licensed under the MIT License and has no third-party runtime library dependencies.

Prebuilt microcontroller firmware images (mimusb_firmware-*) incorporate third-party SDK and USB stack components under permissive licenses:

Firmware asset	Third-party components & licenses
mimusb_firmware-rp2040-*, mimusb_firmware-rp2350-*	TinyUSB 0.18.0 (MIT), Raspberry Pi Pico SDK 2.2.0 (BSD-3-Clause, Copyright (c) 2020 Raspberry Pi (Trading) Ltd.), Arm CMSIS Core (Apache-2.0), Newlib C runtime
mimusb_firmware-nrf52840-*	TinyUSB 0.18.0 (MIT), Nordic Semiconductor nrfx (BSD-3-Clause, Copyright (c) 2017-2024 Nordic Semiconductor ASA), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-stm32f4-*	TinyUSB 0.18.0 (MIT), STMicroelectronics cmsis_device_f4 & stm32f4xx_hal_driver (BSD-3-Clause / Apache-2.0, Copyright (c) 2016-2019 STMicroelectronics), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-esp32s3-*	TinyUSB 0.18.0 (MIT), Espressif ESP-IDF v5.4.2 (Apache-2.0, Copyright 2015-2025 Espressif Systems), Amazon FreeRTOS Kernel (MIT), Newlib C runtime

Complete copyright notices, license texts, and warranty disclaimers for all firmware binaries are provided in the release asset mimusb_firmware-THIRD_PARTY_NOTICES-0.6.1.txt and in THIRD_PARTY_NOTICES.md / NOTICE.

v0.6.0

The C ABI changes: one way to open a Node. A Spec says what a function is, a placement says where
it goes on a Device. The wire protocol is unchanged; the firmware has one fix (below).

Hardware-verified on 2026-11-13 (see "Run on a board") for the parts listed there. A 0.5.0
board has to be flashed with this release's firmware, because the library refuses a board of another
minor version.

Run on a board

2026-11-13, a Raspberry Pi Pico (RP2040) flashed with this release's firmware image through
mimusb_device_enter_bootloader, a Prolific PL2303 adapter (7,812,500 baud), the target the same
Linux machine (a VMware guest, both USB devices passed through). Not run: a second machine as the
target, Windows or macOS, the RP2350, the other boards, the mimusb_verify_* programs.

• hw_bulk wait|newest|oldest, hw_control_rules, hw_composite, hw_bytes bytes|bos, hw_iso,
  hw_cdc: all passed, with no error on the link counters.
• hw_msc (new): a mass storage function; the kernel's usb-storage found the disk, 4 KiB reads and
  writes matched byte for byte, and the Bulk-Only Mass Storage Reset passed. It failed before the
  firmware fix below: the first CBW after a clear_halt of an endpoint that was not halted was lost.
• hw_ecm (new): a CDC-ECM network adapter; the kernel made the interface, ARP and ICMP echo of frames
  from 60 to 1514 bytes and 200 full-size round trips passed.
• hw_dfu, hw_printer (the kernel's usblp bound it), hw_midi (the kernel's snd-usb-audio made a
  sound card) (all new): passed.

Changed

• mimusb_node_open(device, spec, placement, timeouts, &node) is the only way to open a Node. It
  replaces mimusb_node_open_profile and the old mimusb_node_open(device, node_config, ...).
• mimusb_node_placement (interface number, string, the endpoints of the Spec's roles) replaces
  mimusb_hid_node_config, which is gone together with mimusb_hid_node_config_init.
  mimusb_node_placement_init and mimusb_placed_endpoint are new.
• The HID descriptor and Interface descriptor values (bcd_hid, subclass, protocol,
  country_code) moved from the Node's config to the Spec: every HID options structure ends with a
  required mimusb_hid_function function. A zero bcd_hid is MIMUSB_ERR_UNSET_FIELD.
• Any class of Node is a Spec too: mimusb_spec_create_interfaces(mimusb_node_config*) copies the
  interfaces, items and rules into a Spec of kind MIMUSB_PROFILE_INTERFACES, which is opened with
  an empty placement.

Fixed

• Firmware (RP2040, RP2350): CLEAR_FEATURE(ENDPOINT_HALT) on an endpoint that was not halted left an
  armed OUT transfer expecting the old data toggle, so the target's next packet (DATA0) was taken for
  a retransmission and dropped. The toggle is now returned to DATA0 at once (USB 2.0 9.4.5), which is
  what a Bulk-Only Mass Storage Reset needs.

Added

• mimusb_spec_roles lists the endpoint roles of a Spec (MIMUSB_HID_ROLE_IN, required;
  MIMUSB_HID_ROLE_OUT, optional), so a caller sees what its placement must give.
• Refusals with the field named in mimusb_error_detail: a role given twice or one the Spec does not
  have, a nonzero reserved field, a missing IN role, a non-empty placement for a Spec of interfaces.

---

Firmware Binary Third-Party Notices

The host library (libmimusb) is licensed under the MIT License and has no third-party runtime library dependencies.

Prebuilt microcontroller firmware images (mimusb_firmware-*) incorporate third-party SDK and USB stack components under permissive licenses:

Firmware asset	Third-party components & licenses
mimusb_firmware-rp2040-*, mimusb_firmware-rp2350-*	TinyUSB 0.18.0 (MIT), Raspberry Pi Pico SDK 2.2.0 (BSD-3-Clause, Copyright (c) 2020 Raspberry Pi (Trading) Ltd.), Arm CMSIS Core (Apache-2.0), Newlib C runtime
mimusb_firmware-nrf52840-*	TinyUSB 0.18.0 (MIT), Nordic Semiconductor nrfx (BSD-3-Clause, Copyright (c) 2017-2024 Nordic Semiconductor ASA), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-stm32f4-*	TinyUSB 0.18.0 (MIT), STMicroelectronics cmsis_device_f4 & stm32f4xx_hal_driver (BSD-3-Clause / Apache-2.0, Copyright (c) 2016-2019 STMicroelectronics), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-esp32s3-*	TinyUSB 0.18.0 (MIT), Espressif ESP-IDF v5.4.2 (Apache-2.0, Copyright 2015-2025 Espressif Systems), Amazon FreeRTOS Kernel (MIT), Newlib C runtime

Complete copyright notices, license texts, and warranty disclaimers for all firmware binaries are provided in the release asset mimusb_firmware-THIRD_PARTY_NOTICES-0.6.0.txt and in THIRD_PARTY_NOTICES.md / NOTICE.

v0.5.0

Not hardware-verified. Nothing of this release was run on a board: the simulated board (the
firmware core on a fake HAL) and the scripted board cover it. The wire protocol and the firmware
behaviour are unchanged from 0.4.0; the firmware images differ only in the version they report.
The C ABI changes (mimusb_usb_endpoint is 12 bytes, mimusb_usb_interface has settings), so a
program built against 0.4.0 needs the changes below, and the shared library keeps SOVERSION 0
while the version is 0.x.

Added

• mimusb_cdc_acm_descriptors_make and mimusb_cdc_acm_rules: the class descriptors, the
  Interface Association descriptor and the line-coding control rules of a CDC-ACM function, for a
  Node opened with mimusb_node_open.

Changed

• An interface of a Node is a list of alternate settings, and a setting is a sequence of
  items (mimusb_usb_interface.settings, mimusb_usb_setting, mimusb_usb_item): an endpoint
  or one whole descriptor, in bus order. This replaces class_descriptors, endpoints and
  endpoint_count, and takes class descriptors that sit between or after endpoints (CDC, audio,
  video, MIDI). mimusb_usb_endpoint is 12 bytes: it gains audio_form, refresh,
  synch_address, sync_type and usage_type for the 9-byte audio endpoint form and the
  isochronous synchronization and usage types.

• A Node can carry isochronous endpoints, in a setting other than 0; INTERFACE_ALTERNATE names
  the Node that owns the interface (node_id). Nodes and Devices given as bytes share one
  endpoint check.

• Renamed from libmimhid to libmimusb, because the library is no longer about HID alone. Every
  public name changes with it: the mimhid_ prefix is mimusb_, MIMHID_ is MIMUSB_, the
  headers are mimusb.h and mimusb.hpp, the CMake package is mimusb (targets mimusb::mimusb,
  mimusb::mimusb_static, mimusb::cpp), the pkg-config files are mimusb.pc and
  mimusb-static.pc, the CMake options are MIMUSB_*, the Python, Rust and C# packages are
  mimusb, mimusb-sys and MimUsb, and the repository is nemarpuc/libmimusb. The wire
  protocol and the firmware behaviour are unchanged; the names in proto/mimusb_proto.h change
  with the prefix. Code that uses 0.4.0 changes names only.

---

Firmware Binary Third-Party Notices

The host library (libmimusb) is licensed under the MIT License and has no third-party runtime library dependencies.

Prebuilt microcontroller firmware images (mimusb_firmware-*) incorporate third-party SDK and USB stack components under permissive licenses:

Firmware asset	Third-party components & licenses
mimusb_firmware-rp2040-*, mimusb_firmware-rp2350-*	TinyUSB 0.18.0 (MIT), Raspberry Pi Pico SDK 2.2.0 (BSD-3-Clause, Copyright (c) 2020 Raspberry Pi (Trading) Ltd.), Arm CMSIS Core (Apache-2.0), Newlib C runtime
mimusb_firmware-nrf52840-*	TinyUSB 0.18.0 (MIT), Nordic Semiconductor nrfx (BSD-3-Clause, Copyright (c) 2017-2024 Nordic Semiconductor ASA), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-stm32f4-*	TinyUSB 0.18.0 (MIT), STMicroelectronics cmsis_device_f4 & stm32f4xx_hal_driver (BSD-3-Clause / Apache-2.0, Copyright (c) 2016-2019 STMicroelectronics), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimusb_firmware-esp32s3-*	TinyUSB 0.18.0 (MIT), Espressif ESP-IDF v5.4.2 (Apache-2.0, Copyright 2015-2025 Espressif Systems), Amazon FreeRTOS Kernel (MIT), Newlib C runtime

Complete copyright notices, license texts, and warranty disclaimers for all firmware binaries are provided in the release asset mimusb_firmware-THIRD_PARTY_NOTICES-0.5.0.txt and in THIRD_PARTY_NOTICES.md / NOTICE.

v0.4.0

Not hardware-verified as tests/hw/README.md defines it; what was run on a board is listed under
"Run on a board" below. The wire protocol changes (a new event, a new bit in the PONG's
transfer_types): a 0.3.x board and this library do not talk to each other, and the firmware of
this release is needed to use isochronous endpoints.

Run on a board

2026-11-12, a Raspberry Pi Pico (RP2040), a Prolific PL2303 adapter, a Windows 10 machine as the
target. Not run: Linux, macOS or Android as the target, the RP2350, the other boards, audio
classes, an isochronous OUT endpoint, the mimhid_verify_* programs.

• A UVC camera (128x96 YUY2, 256-byte isochronous packets, descriptors as bytes) enumerated by
  Windows, opened by its camera application, and streamed: four openings and closings of the
  stream in a row, then a program restart with the stream open, three times, with no stop of the
  board and no error on the link counters.
• Before the fix under "Fixed", the second opening of the stream stopped the board (its USB core:
  commands that run there timed out while the serial link still answered) until it was unplugged.

Added

• Alternate settings and isochronous endpoints in a Device given as bytes
  (mimhid_device_set_descriptors): interfaces may have settings 0, 1, 2, ... in order, an endpoint
  may be named by several settings of its interface, and a board whose transfer_types has
  MIMHID_TRANSFER_ISOCHRONOUS (the RP2040 and RP2350 firmware: packets up to 1023 bytes) takes
  isochronous endpoints, which is what the audio and video classes stream on. Endpoint descriptors
  may be 7 bytes or the 9-byte audio-class form. The target's SET_INTERFACE switches the
  isochronous endpoints of the interface and is reported as MIMHID_EVENT_INTERFACE_ALTERNATE
  (wire event SET_INTERFACE, 14); GET_INTERFACE answers the selected setting. The board adds
  nothing to a stream: no padding, no pacing, no resampling.
• mimhid_device_endpoint_write refuses an isochronous transfer longer than the endpoint's packet.
• Simulated-board scenario mimhid.sim-iso, host walker and firmware tests for settings and
  isochronous descriptors.

Fixed

• A target that leaves an alternate setting with an isochronous endpoint and selects it again (a
  camera application closed and opened again) stopped the RP2040 and RP2350 board: the transfer
  armed on the controller was never taken by the target, and TinyUSB's driver stops with "ep was
  already available" when the next one is armed on top of it. SET_INTERFACE now takes the armed
  transfer off the controller of every isochronous endpoint it stops or starts
  (hal_usb_clear_endpoint). Seen on a board: four openings and closings of a UVC stream in a row,
  and a detach while streaming followed by three attaches, with no stop; before, the second opening
  stopped the board until it was unplugged.

Changed

• A Node still has bulk and interrupt endpoints only: an isochronous transfer_type in a Node is
  MIMHID_ERR_UNSUPPORTED (it needs settings, which a Device given as bytes has).
• On a board with isochronous endpoints max_transfer_bytes is its isochronous packet (1023, 64
  before), so a long write to a bulk endpoint goes in frames of up to 960 bytes (a multiple of the
  endpoint's packet size) instead of 64; the target sees the same transfer.
• A configuration for the RP2040 and RP2350 is checked against the controller's 3712 bytes of
  packet memory at COMMIT (NAK_OVERFLOW): the driver stopped the board when it ran out.
• The wire protocol gains an event and the PONG's transfer_types a bit; the firmware version
  number is not changed here (the release's to choose).

---

Firmware Binary Third-Party Notices

The host library (libmimhid) is licensed under the MIT License and has no third-party runtime library dependencies.

Prebuilt microcontroller firmware images (mimhid_firmware-*) incorporate third-party SDK and USB stack components under permissive licenses:

Firmware asset	Third-party components & licenses
mimhid_firmware-rp2040-*, mimhid_firmware-rp2350-*	TinyUSB 0.18.0 (MIT), Raspberry Pi Pico SDK 2.2.0 (BSD-3-Clause, Copyright (c) 2020 Raspberry Pi (Trading) Ltd.), Arm CMSIS Core (Apache-2.0), Newlib C runtime
mimhid_firmware-nrf52840-*	TinyUSB 0.18.0 (MIT), Nordic Semiconductor nrfx (BSD-3-Clause, Copyright (c) 2017-2024 Nordic Semiconductor ASA), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimhid_firmware-stm32f4-*	TinyUSB 0.18.0 (MIT), STMicroelectronics cmsis_device_f4 & stm32f4xx_hal_driver (BSD-3-Clause / Apache-2.0, Copyright (c) 2016-2019 STMicroelectronics), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimhid_firmware-esp32s3-*	TinyUSB 0.18.0 (MIT), Espressif ESP-IDF v5.4.2 (Apache-2.0, Copyright 2015-2025 Espressif Systems), Amazon FreeRTOS Kernel (MIT), Newlib C runtime

Complete copyright notices, license texts, and warranty disclaimers for all firmware binaries are provided in the release asset mimhid_firmware-THIRD_PARTY_NOTICES-0.4.0.txt and in THIRD_PARTY_NOTICES.md / NOTICE.

v0.3.0

Not hardware-verified as tests/hw/README.md defines it; what was run
on a board is listed under "Run on a board" below. The wire protocol and the C ABI change: a
0.2.1 board and this library do not talk to each other. The board becomes a generic USB device: the
host composes every descriptor, or is given them as bytes, and the firmware has no HID driver.

Run on a board

2026-11-12, a Raspberry Pi Pico (RP2040), a Prolific PL2303 adapter, the target the same Linux
machine (a VMware guest, both USB devices passed through). Not run: a second machine as the target,
Windows or macOS, the mimhid_verify_* programs (they type into the target, which here is the
session), the other boards.

• Discovery and the rate search (7,812,500 baud, no errors on the link counters in any run).
• A keyboard profile Node: enumerated by Linux, 10 runs of 400 presses and 400 releases with the
  event device grabbed, none lost; latency in docs/LATENCY.md, not different from 0.2.1.
• A vendor Node with bulk IN and OUT: transfers of 1 to 292 bytes with their boundaries, a
  zero-length packet, 262,100 bytes without loss under the wait policy, 200 packets from the target,
  the drop-newest and drop-oldest policies with a target that does not read, stall and clear.
• An HID interface written by hand: every control rule action answered to the host (ANSWER,
  ANSWER_LAST_SENT, ACCEPT with a data stage, ASK, a stall for a request no rule matches), a
  rule's bytes replaced, and an Output report on the OUT endpoint.
• A composite device opened in one batch: a keyboard profile and a two-interface Node with an
  interface association.
• A device given as bytes (tests/hw/hw_bytes bytes): the device, configuration and BOS descriptors and
  two strings read back by Linux byte for byte, the vendor request answered by a rule of the Device,
  bulk IN with its boundaries and a zero-length packet, bulk OUT as events of node 0 (a transfer of 70
  bytes is two packets), Halt and clear. A composed Device with a BOS descriptor and bcdUSB 0x0210
  (hw_bytes bos). The BOS of both names the Microsoft OS 2.0 capability, so the target asks for its
  descriptor set and the Device has a rule that answers; without it, or with bcdUSB 0x0210 and no BOS,
  the target did not enumerate the device. Not run: Windows.
• hw_bulk wait|newest|oldest, hw_control_rules and hw_composite again on the same firmware; the
  latency of ten runs in docs/LATENCY.md.
• mimhid_device_enter_bootloader, used to write the firmware some forty times.

Wire protocol

• The host sends every descriptor as bytes. DESC_RESET (0x10), DESC_BEGIN (0x11) and
  DESC_DATA (0x12) carry the device, configuration, string, BOS and ANSWER descriptors
  (MIMHID_DESC_*); they replace DEVICE_CONFIG, NODE_BEGIN and NODE_DATA. At COMMIT the board
  walks the staged configuration once and refuses one that does not hold together (NAK_DESCRIPTOR, the
  previous configuration kept; docs/PROTOCOL.md).
• A BOS descriptor is a descriptor kind (MIMHID_DESC_BOS, 6) the board serves byte for byte; it needs
  bcdUSB 0x0201 or more.
• Data frames name endpoints. EP_IN (0x41..0x4F) and EP_OUT (0xC1..0xCF) carry the endpoint
  number, not a node id. New commands EP_CONFIG (0x1B, replaces QUEUE_DEPTH: address, depth, policy
  drop-newest, drop-oldest or wait), EP_STALL (0x1E), EP_FLUSH (0x1F), RULE (0x18, was
  CONTROL_CONFIG), RULES_APPLY (0x21), RULE_DATA (0x22), BOOTLOADER (0x20); new events
  EV_EP_DONE, EV_EP_HALT; REPORT_LOST became TRANSFER_LOST, which names the endpoint.
  DESC_HID_REPORT (4), FEATURE (0x14) and the events SET_REPORT, SET_PROTOCOL, SET_IDLE,
  OUTPUT_REPORT (5 to 8) are gone and not reused.
• An ANSWER rule has a capacity and a length (RULE bytes 14..15 and 16..17). The board reserves the
  capacity, RULE_DATA sets any length up to it, so a shortened answer can grow again after the table
  is rebuilt.
• A COMMIT that attaches is refused with NAK_STATE while the board is attached: it would change
  the descriptors under a device the target has enumerated. mimhid_device_connect on a configured
  Device sends nothing and returns MIMHID_OK.
• PONG (MIMHID_PONG_MIN_LEN 49): bytes 4, 5, 21..22 and 25..26 are reserved, zero; new fields
  max_endpoint_number (34), max_interfaces_any, max_config_descriptor_bytes, max_strings,
  max_transfer_bytes, endpoint_queue_slots, transfer_types (36 to 44), max_answer_bytes (45..46)
  and max_bos_bytes (47..48); the unique id starts at 49. The board's limits: 160 rules, 4096 bytes of
  answers, 32 ANSWER_LAST_SENT rules, 256 bytes of BOS (MIMHID_CONTROL_RULES, MIMHID_ANSWER_BYTES,
  MIMHID_LAST_SENT_SLOTS, MIMHID_MAX_BOS_BYTES).

API

• mimhid_node_open takes interfaces of any class, HID included (mimhid_node_config: interfaces,
  bulk and interrupt endpoints, class descriptors, an interface association, control rules). Profile
  Nodes (keyboard, mouse, ...) are mimhid_node_open_profile with mimhid_hid_node_config. Helpers
  mimhid_hid_descriptor_bytes and mimhid_hid_descriptor_rule; examples vendor_bulk.c and
  hid_interface.c.
• A Device can be given as bytes: mimhid_device_set_descriptors / _clear_descriptors
  (mimhid_device_descriptors), raw strings mimhid_device_set_string / _clear_string (any index and
  language), and the endpoint calls by address mimhid_device_endpoint_set_policy, _write, _stall,
  _clear_stall, _flush. The library checks the bytes without reading any class and names the field
  and the byte offset of what is wrong. The OUT data of such a device is MIMHID_EVENT_ENDPOINT_DATA
  with node id 0. It is exclusive with Nodes (MIMHID_ERR_BUSY both ways). Example
  examples/c/device_from_descriptors.c.
• BOS descriptor: mimhid_device_set_bos for a composed Device, or in mimhid_device_descriptors;
  mimhid_board_limits.max_bos_bytes. A commit with a BOS and a bcd_usb below 0x0201 is
  MIMHID_ERR_PARAM. Example examples/c/winusb_bulk.c (the Microsoft OS 2.0 platform capability and
  the vendor request that answers it): not run on Windows.
• Control rules replace control routing: mimhid_device_set_control_rules, mimhid_device_set_rule_data,
  mimhid_node_set_rule_data; actions MIMHID_CONTROL_ANSWER, _ANSWER_LAST_SENT, _ACCEPT, _ASK
  (timeout_ms, when_late), _STALL; the rules of the Nodes come first, then the Device's. A request
  no rule matches is stalled apart from the standard requests of the stack. New flag
  MIMHID_CONTROL_FLAG_ACCEPTED. mimhid_*_set_rule_data takes any length up to the rule's capacity.
• Endpoint calls of a Node: mimhid_node_endpoint_write, _stall, _clear_stall, _flush,
  _set_policy (replacing mimhid_node_set_queue_depth); a profile Node's IN endpoint takes them too, with
  any of the three policies; a write longer than the board's frame limit is split, and a timeout of 0 is
  accepted with a drop policy. mimhid_device_add_string / _remove_string. New events
  MIMHID_EVENT_ENDPOINT_DATA, _ENDPOINT_HALT, _TRANSFER_LOST (replacing REPORT_LOST).
• iface.number is the real bInterfaceNumber. The numbers in use are 0, 1, 2, ... without a gap;
  otherwise the commit fails with MIMHID_ERR_PARAM before anything is sent, the missing number in
  mimhid_error_detail.offset. Open Nodes in number order (or in one batch) and close the highest first.
• Limits: the 16-Node limit is gone (up to 65534 within the board's limits);
  mimhid_device_info.max_nodes and mimhid_board_limits.max_hid_interfaces are removed
  (max_answer_bytes and the new fields replace them).
• Removed: mimhid_node_open_raw, mimhid_report_send, mimhid_device_set_control_routing,
  MIMHID_CONTROL_MAX_RULES, MIMHID_HID_ITFS, MIMHID_NODE_DATA_CHUNK (now MIMHID_DESC_DATA_CHUNK),
  MIMHID_DEVFLAG_SERIAL_FROM_ID (now MIMHID_DESC_F_SERIAL_FROM_ID).
• Changed for the target and the program:
  • A Feature report read with no answer set is stalled (it was an empty answer).
  • GET_REPORT of an Input report returns the last report sent with that Report ID.
  • A GET_IDLE straight after a SET_IDLE may still return the old value for one round trip.
  • MIMHID_EVENT_OUTPUT_REPORT / _FEATURE_REPORT for a SET_REPORT arrive when its data stage has.
  • Nodes on a shared interface that use the wait policy count against the first live Node of it.
  • A Device with no Node holds no rules: they are kept until the first commit; inside a batch a change
    of rules marks the Device for the commit at the end.
  • A COMMIT applies the staged rules with report_all 0; the library sends RULES_APPLY with it
    straight after an attach when it is set.

Firmware

• The firmware builds no descriptor and has no HID driver (CFG_TUD_HID is 0). Every interface runs
  on a generic driver (firmware/common/generic.c, TinyUSB 0.18.0's usbd_edpt_*); what HID asks of
  endpoint 0 is a table of control rules (control.c: two copies, RULES_APPLY swaps them and
  RULE_DATA changes an answer in place, both NAK_BUSY while an answer is being sent). The ESP32-S3
  port's hid_device.c is removed.
• A BOS descriptor is served by tud_descriptor_bos_cb; none is a stall.
• firmware/tests/itfs_probe.c is now port_probe.c.

A board a program left attached

• The board leaves the bus before every configuration, the first of a Device too. A program that
  ended without closing its Device (or closed it with keep_attached) leaves the board on the
  target's bus. The next program's first configuration used to reach a board that was attached:
  its descriptors changed under a device the target had already enumerated, the target never saw
  the new device, and `mi...

v0.2.1

Not hardware-verified. The wire protocol and the C ABI are those of 0.2.0 (a 0.2.0 board and this library
talk to each other); this release fixes four bugs, changes the release packaging and adds tests and
documentation. None of it has run on a board. Asset names changed: a script that downloads the old
-shared / -static names must be changed.

Fixed

• Null options and configuration pointers are recorded in mimhid_last_error. Passing a null
  options or config pointer to the nine mimhid_spec_create_* factories, mimhid_device_open,
  mimhid_node_open, mimhid_node_open_raw, or the calls taking mimhid_commit_timeouts now
  populates mimhid_last_error() with MIMHID_ERR_PARAM and the structure name instead of leaving
  the thread-local error detail at MIMHID_OK.
• Frame type names. mimhid_frame_type_name now returns "PROBE" for MIMHID_T_PROBE
  (0x1C) and "COUNTERS" for MIMHID_T_COUNTERS (0x1D).
• 3-byte detach COMMIT on close. mimhid_device_close now sends the standard 3-byte
  {1, 0, 0} detach COMMIT payload matching Link::disconnect and commit_device instead of a
  1-byte {1} payload.
• device->closing check across all device calls. mimhid_device_wait_ready,
  mimhid_device_remote_wakeup, mimhid_device_board_info, mimhid_device_link_counters, and
  mimhid_device_limits now reject a closing mimhid_device* with MIMHID_ERR_PARAM, matching
  the other device operations.

Changed

• Tests. A scripted board on a pseudo-terminal (mimhid.scripted) tests the transport and the C
  ABI when the board NAKs, stays silent, refuses a rate or hangs up; new unit suites cover every
  factory and input refusal. The pseudo-terminal tests of the real firmware core are now called
  sim (mimhid.sim-*). A Coverage CI job measures src/ with gcovr. tests/README.md describes
  the unit, scripted, sim and hardware layers; tests/hw/README.md is the hardware procedure;
  docs/VERIFICATION.md summarizes what is verified across all four layers.
• The release no longer publishes *-runtime bundles. The *-shared archive already carries the
  shared library with the same license documents, and nothing in the project consumed the smaller
  bundle. A release now has 35 assets instead of 41.
• One archive per platform, one SBOM per release; asset names change. Each platform's archive
  is now libmimhid-X.Y.Z-<platform>-<arch>[-ubuntu22.04].tar.gz|zip, without the -shared /
  -static suffix, and holds both libraries (the static one is libmimhid_static.a /
  mimhid_static.lib), the CMake package files of both components and both pkg-config files;
  find_package(mimhid COMPONENTS shared) and COMPONENTS static both work from it. The twelve
  .spdx.json sidecars are replaced by libmimhid-X.Y.Z.spdx.json, one SPDX 2.3 document with a
  package per archive. A release has 18 assets instead of 35; a script that downloads the old
  names must be changed. The release workflow also gained a workflow_dispatch dry run
  (dry_run, on by default) that builds and checks every asset and keeps them as a workflow
  artifact without publishing anything.

---

Firmware Binary Third-Party Notices

The host library (libmimhid) is licensed under the MIT License and has no third-party runtime library dependencies.

Prebuilt microcontroller firmware images (mimhid_firmware-*) incorporate third-party SDK and USB stack components under permissive licenses:

Firmware asset	Third-party components & licenses
mimhid_firmware-rp2040-*, mimhid_firmware-rp2350-*	TinyUSB 0.18.0 (MIT), Raspberry Pi Pico SDK 2.2.0 (BSD-3-Clause, Copyright (c) 2020 Raspberry Pi (Trading) Ltd.), Arm CMSIS Core (Apache-2.0), Newlib C runtime
mimhid_firmware-nrf52840-*	TinyUSB 0.18.0 (MIT), Nordic Semiconductor nrfx (BSD-3-Clause, Copyright (c) 2017-2024 Nordic Semiconductor ASA), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimhid_firmware-stm32f4-*	TinyUSB 0.18.0 (MIT), STMicroelectronics cmsis_device_f4 & stm32f4xx_hal_driver (BSD-3-Clause / Apache-2.0, Copyright (c) 2016-2019 STMicroelectronics), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimhid_firmware-esp32s3-*	TinyUSB 0.18.0 (MIT), Espressif ESP-IDF v5.4.2 (Apache-2.0, Copyright 2015-2025 Espressif Systems), Amazon FreeRTOS Kernel (MIT), Newlib C runtime

Complete copyright notices, license texts, and warranty disclaimers for all firmware binaries are provided in the release asset mimhid_firmware-THIRD_PARTY_NOTICES-0.2.1.txt and in THIRD_PARTY_NOTICES.md / NOTICE.

v0.2.0

The wire protocol, the C ABI and the firmware build interface change; a 0.1.0 board and a 0.2.0
library do not talk to each other (MIMHID_ERR_PROTOCOL), and the reverse. Not
hardware-verified: the changes are tested with the firmware core's own tests, with the simulated
board over a pseudo-terminal, and by building every port (RP2040, RP2350, nRF52840, STM32F4;
the ESP32-S3 build is left to CI); none of it has run on a board yet.

• Nothing about the chip is assumed by the firmware build. Each port states the interfaces
  (MIMHID_HID_ITFS), the highest endpoint number (MIMHID_MAX_ENDPOINT_NUMBER), the endpoint
  packet size (MIMHID_MAX_ENDPOINT_BYTES), CFG_TUSB_OS, CFG_TUSB_RHPORT0_MODE and
  CFG_TUD_MAX_SPEED on the command line; a missing one is a compile error that names it. The
  nRF52840 no longer gets 7 by default, core.h no longer picks 15 for the RP chips from
  PICO_RP2040, and tusb_config.h no longer defaults to full speed and no OS. The Pico build
  needs PICO_PLATFORM, PICO_BOARD, MIMHID_UART_ID, MIMHID_UART_TX_PIN and
  MIMHID_UART_RX_PIN; the ESP32-S3 build both pins; the nRF52840 and STM32F4 builds -DBOARD
  (the STM32F4 port records the endpoint count of each board's MCU and refuses an unlisted board,
  and gives the F412 boards 5 interfaces, not 3).
• A number the controller does not have is refused. Until now an endpoint address such as
  0x8F was accepted by the host and the board, TinyUSB then failed the target's
  SET_CONFIGURATION, and the commit ended in MIMHID_ERR_TIMEOUT (on the nRF52840 the endpoint
  number 8 was opened as a corrupt isochronous endpoint without an error). The PONG now carries
  max_endpoint_number (byte 34; the unique id moved to 35 and 36..; MIMHID_PONG_MIN_LEN 36),
  mimhid_device_info.reserved8 became max_endpoint_number, mimhid_board_limits gained
  max_endpoint_number (its size is 36), and mimhid_node_open returns MIMHID_ERR_OVERFLOW
  for a larger number. The firmware refuses it with NAK_OVERFLOW.
• The firmware fills nothing in. A zero LANGID, bcdUSB, bcdHID, IN endpoint address, size
  or interval, an bmAttributes without bit 7, and an OUT endpoint that is only partly given are
  refused (NAK_PARAM); a COMMIT whose nodes of one interface differ, or that uses an endpoint
  number twice in one direction, is refused (NAK_DESCRIPTOR). The host library already
  required all of these, so a program that works with the library is not affected.
• The initializers fill nothing in. Every mimhid_*_init function (and its mimhid:: twin)
  zeroes the structure and sets struct_size, and nothing else: the pid.codes test IDs, the
  strings, the boot rate, the handshake and commit timeouts, the report size, the Linux HID limits,
  bm_attributes, the node's class, bcdHID, endpoint and interval, and every profile's fields
  (the mouse buttons and ranges, the keyboard Usages, the gamepad axes, the touch and pen
  fields) are the program's to set, and a required one left at zero is refused with
  MIMHID_ERR_UNSET_FIELD. mimhid_node_config_init and mimhid::node_config() lost their
  interface_number argument (set iface.number and ep_in.address yourself), and the four
  constants MIMHID_CONTROL_TIMEOUT_MS, MIMHID_SEND_TIMEOUT_MS, MIMHID_DRAIN_TIMEOUT_MS and
  MIMHID_RECONNECT_TIMEOUT_MS are gone. The README, docs/API.md (which lists what each
  structure requires) and the examples show every value set.
• A vendor ID of zero is refused. usb_device.vendor_id joined bcd_usb, language_id and
  ep0_max_packet_size as a field the library will not guess, so a program that forgot it no
  longer presents 0000:xxxx (or, until now, the pid.codes test IDs the initializer used to put
  in). A product ID of zero is still a valid one.
• nRF52840: the D+ pull-up is taken down again after every USB power event until a
  configuration is committed, so a board that has not been committed no longer enumerates as
  CAFE:4000 with no interface when the cable is plugged in.

---

Firmware Binary Third-Party Notices

The host library (libmimhid) is licensed under the MIT License and has no third-party runtime library dependencies.

Prebuilt microcontroller firmware images (mimhid_firmware-*) incorporate third-party SDK and USB stack components under permissive licenses:

Firmware asset	Third-party components & licenses
mimhid_firmware-rp2040-*, mimhid_firmware-rp2350-*	TinyUSB 0.18.0 (MIT), Raspberry Pi Pico SDK 2.2.0 (BSD-3-Clause, Copyright (c) 2020 Raspberry Pi (Trading) Ltd.), Arm CMSIS Core (Apache-2.0), Newlib C runtime
mimhid_firmware-nrf52840-*	TinyUSB 0.18.0 (MIT), Nordic Semiconductor nrfx (BSD-3-Clause, Copyright (c) 2017-2024 Nordic Semiconductor ASA), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimhid_firmware-stm32f4-*	TinyUSB 0.18.0 (MIT), STMicroelectronics cmsis_device_f4 & stm32f4xx_hal_driver (BSD-3-Clause / Apache-2.0, Copyright (c) 2016-2019 STMicroelectronics), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimhid_firmware-esp32s3-*	TinyUSB 0.18.0 (MIT), Espressif ESP-IDF v5.4.2 (Apache-2.0, Copyright 2015-2025 Espressif Systems), Amazon FreeRTOS Kernel (MIT), Newlib C runtime

Complete copyright notices, license texts, and warranty disclaimers for all firmware binaries are provided in the release asset mimhid_firmware-THIRD_PARTY_NOTICES-0.2.0.txt and in THIRD_PARTY_NOTICES.md / NOTICE.

v0.1.0

The first release of this line. Not hardware-verified: the host library, the protocol and the
firmware core are tested with a simulated board over a pseudo-terminal and with the firmware
core's own tests; an earlier firmware ran on a Raspberry Pi Pico, this one has not yet.

• What it is. A PC-managed USB emulation coprocessor: a host library (C ABI in
  include/mimhid.h, header-only C++ forwarders in mimhid.hpp, Python, C# and Rust bindings) and
  the firmware of a board that turns serial frames into the reports of a USB HID composite
  device. Boards: RP2040 and RP2350 (the reference), STM32F4, nRF52840 and ESP32-S3 (build-only
  ports).
• Devices and Nodes. A Device is one board on one serial port. Its Nodes are HID interfaces
  with an immutable specification: keyboard, mouse, touchscreen, touchpad, pen, digitizer, gamepad,
  toggle controls, or a raw report descriptor. Descriptors, interface and endpoint numbers, polling intervals, strings
  and the USB identity are given by the program; nothing is inferred.
• Strings are Unicode. UTF-8 on the API, UTF-16 in the string descriptor (USB 2.0 9.6.7), up
  to 126 code units; control characters and malformed text are refused.
• The line is as fast as it carries. Frames end in a CRC-16/CCITT-FALSE. There is no table of
  rates: the board starts at 115,200 baud and makes any rate its UART divider gives within 2 %;
  MIMHID_BAUD_FASTEST measures the fastest rate the port, adapter and board carry without loss
  (counters on the board judge it). A UART BREAK returns a board to the boot rate, so a program
  that went away cannot lose it. mimhid_device_link_counters reads the board's error counters.
• Versions. The firmware and the library of one release agree on the protocol: a host talks to
  a board whose major and minor version equal its own. A board of another version is listed by
  mimhid_discover with only its version and refused with MIMHID_ERR_PROTOCOL.
• Control transfers. Control routing rules hand chosen requests to the program, which answers
  them (a proxy of a real device is built on this); Feature reports, idle and protocol requests,
  output reports and the other events are reported to the program.
• Reports are sent through a per-Node queue with optional loss reporting; batches commit a
  configuration change once.
• Build and release. CMake presets (dev, release, tsan), an ABI golden file, symbol
  lint, and release archives for Linux, macOS and Windows with the firmware images.

---

Firmware Binary Third-Party Notices

The host library (libmimhid) is licensed under the MIT License and has no third-party runtime library dependencies.

Prebuilt microcontroller firmware images (mimhid_firmware-*) incorporate third-party SDK and USB stack components under permissive licenses:

Firmware asset	Third-party components & licenses
mimhid_firmware-rp2040-*, mimhid_firmware-rp2350-*	TinyUSB 0.18.0 (MIT), Raspberry Pi Pico SDK 2.2.0 (BSD-3-Clause, Copyright (c) 2020 Raspberry Pi (Trading) Ltd.), Arm CMSIS Core (Apache-2.0), Newlib C runtime
mimhid_firmware-nrf52840-*	TinyUSB 0.18.0 (MIT), Nordic Semiconductor nrfx (BSD-3-Clause, Copyright (c) 2017-2024 Nordic Semiconductor ASA), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimhid_firmware-stm32f4-*	TinyUSB 0.18.0 (MIT), STMicroelectronics cmsis_device_f4 & stm32f4xx_hal_driver (BSD-3-Clause / Apache-2.0, Copyright (c) 2016-2019 STMicroelectronics), Arm CMSIS 5 (Apache-2.0), Newlib C runtime
mimhid_firmware-esp32s3-*	TinyUSB 0.18.0 (MIT), Espressif ESP-IDF v5.4.2 (Apache-2.0, Copyright 2015-2025 Espressif Systems), Amazon FreeRTOS Kernel (MIT), Newlib C runtime

Complete copyright notices, license texts, and warranty disclaimers for all firmware binaries are provided in the release asset mimhid_firmware-THIRD_PARTY_NOTICES-0.1.0.txt and in THIRD_PARTY_NOTICES.md / NOTICE.