mirror of
https://github.com/hathach/tinyusb.git
synced 2025-01-17 05:32:55 +08:00
53 lines
2.9 KiB
Markdown
53 lines
2.9 KiB
Markdown
This README describes the layout of system files and headers for
|
|
microcontrollers supported by tinyusb from the vendor [ST](www.st.com).
|
|
|
|
The CMSIS by ARM is an attempt to unify how system initialization and headers
|
|
for ARM microcontrollers are handled across vendors. A vendor is expected to
|
|
provide a number of files, including vendor-specific device headers,
|
|
vendor-specific system init code (in C), vendor-specific startup code (coded in
|
|
assembly _and_ meant to make writing C interrupt handlers easy), and ARM
|
|
architecture-specific headers. In practice, it's actually difficult to find all
|
|
these files in one place.
|
|
|
|
* stm32cube generates a self-contained application. All the relevant headers,
|
|
system init, and startup code are under `Drivers/CMSIS`. The linker script is
|
|
stored at the root of your project, _along_ with a copy of the startup code.
|
|
Relative to `Drivers/CMSIS`:
|
|
* Device header files are stored under `Device/ST/$family/Include`.
|
|
* Arm-provided CMSIS headers are stored under `Include`.
|
|
* The portable C portion of the startup code, called `system_$family.c`, is
|
|
stored under `Device/ST/$family/Source/Templates`. This "system init" code
|
|
is required by CMSIS.
|
|
* The assembly portion of the startup code, called `startup_$device.c`, is
|
|
stored under `Device\ST\STM32F4xx\Source\Templates\gcc`.
|
|
|
|
* Micropython maintains [a repo](https://github.com/micropython/stm32lib)
|
|
with _only_ the device header files. We use that
|
|
repo and provide the remaining files ourselves.
|
|
* Micropython keeps the linker script and assembly portion of the startup
|
|
code under the
|
|
[boards](https://github.com/micropython/micropython/tree/master/ports/stm32/boards)
|
|
directory in the stm32 port (but the code is board agnostic).
|
|
* Micropython also embeds its own
|
|
[copy](https://github.com/micropython/micropython/tree/master/lib/cmsis/inc)
|
|
of CMSIS headers for all ARM targets into the repo.
|
|
* Micropython indeed _does_ use their own custom C startup code (CMSIS system
|
|
init) for
|
|
[stm32](https://github.com/micropython/micropython/blob/master/ports/stm32/system_stm32.c)
|
|
targets. It is
|
|
[missing](https://github.com/micropython/micropython/commit/fdbc22e4d27b9d1c686647c9c67a32206f7bc83a)
|
|
the `SystemCoreClockUpdate` function.
|
|
|
|
* TinyUSB uses Micropython's [stm32lib](stm32lib) as a submodule to provide
|
|
device headers. The remaining system files can be found in the following
|
|
directories:
|
|
* C system init code is in the [system-init](system-init) directory.
|
|
* Assembly startup code is in the [startup](startup) directory. Each family
|
|
gets its own subdirectory under startup (e.g. [stm32f4](startup/stm32f4)).
|
|
* ARM-provided headers are stored in the [cmsis](cmsis) directory.
|
|
* The linker script for the STM32F4-DISCOVERY board demo is supplied as
|
|
part of TinyUSB's
|
|
[Board Support Packages](../../bsp/stm32f407g_disc1/STM32F407VGTx_FLASH.ld).
|
|
The above files were extracted from a dummy stm32cube project in February
|
|
2019.
|