#stm32 #pac #interrupt #metadata


Peripheral Access Crate (PAC) for all STM32 chips, including metadata

9 major breaking releases

9.0.0 May 25, 2023
8.0.0 May 19, 2023
7.0.0 May 2, 2023
6.0.0 Apr 11, 2023
0.0.0 Jun 15, 2021

#102 in Embedded development

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stm32-data is a project aiming to produce clean machine-readable data about the STM32 microcontroller families, including:

  • ✔️ Base chip information
    • RAM, flash
    • Packages
  • ✔️ Peripheral addresses and interrupts
  • ✔️ Interrupts
  • ✔️ GPIO AlternateFunction mappings (for all families except F1)
  • ❌ GPIO mappings for F1
  • 🚧 Register blocks for all peripherals
  • ✔️ DMA stream mappings
  • ❌ Per-package pinouts
  • ✔️ Links to applicable reference manuals, datasheets, appnotes PDFs.

✔️ = done, 🚧 = work in progress, ❌ = to do

Data sources

These are the data sources currently used.

  • STM32Cube database:
    • List of all MCUs
    • Peripheral versions
    • Flash, RAM size
    • GPIO AF mappings
    • Interrupt mappings (which signals from which peripherals are OR'd into a NVIC interrupt line)
    • DMA channel request mappings
    • Packages and package pinouts (TODO)
  • STM32Cubeprog database
    • Flash, RAM size
  • STM32 mcufinder:
    • Links to documentation PDFs (reference manuals, datasheets...)
  • STM32 HAL headers:
    • interrupt number, name
    • peripheral addresses
  • stm32-rs SVDs: register blocks. YAMLs are intially extracted from SVDs, manually cleaned up and committed. From this point on, they're manually maintained (we don't maintain "patches" for registers)

Install pre-requisites

In order to run the generator, you will need to install the following tools:

  • wget
  • git
  • jq
  • svdpip3 install svdtools
  • xmltodict - pip3 install xmltodict

Generate the stm32-metapac crate

  • Run ./d download-all

    This will download all the required data sources into sources/.

  • Run cargo run --release --bin stm32-data-gen

    This generates all the intermediate JSON's in build/data/.

    Assignments of registers to peripherals is done in a perimap and fixes to registers can be done in the files located in data/registers.

  • Run cargo run --release --bin stm32-metapac-gen

This generates the stm32-metapac crate into build/stm32-metapac/.

Adding support for a new peripheral

This will help you add support for a new peripheral to all STM32 families. (Please take the time to add it for all families, even if you personally are only interested in one. It's easier than it looks, and doing all families at once is significantly less work than adding one now then having to revisit everything later when adding more. It also helps massively in catching mistakes and inconsistencies in the source SVDs.)

  • First, make sure you can generate the YAMLs following the steps above. You should be able to regenerate the already-committed yamls, and end up with no diff.
  • Install chiptool with ./d install-chiptool
  • Run ./d extract-all LPUART1. This'll output a bunch of yamls in tmp/LPUART1. NOTE sometimes peripherals have a number sometimes not (LPUART1 vs LPUART). You might want to try both and merge the outputted YAMLs into a single directory.
  • Diff them between themselves, to identify differences. The differences can either be:
    • 1: Legitimate differences between families, because there are different LPUART versions. For example, added registers/fields.
    • 2: SVD inconsistencies, like different register names for the same register
    • 3: SVD mistakes (yes, there are some)
    • 4: Missing stuff in SVDs, usually enums or doc descriptions.
  • Identify how many actually-different (incompatible) versions of the peripheral exist, as we must not merge them. Name them v1, v2.. (if possible, by order of chip release date, see here.
  • For each version, pick the "best" YAML (the one that has less enums/docs missing), place them in data/registers/lpuart_vX.yaml
  • Cleanup the register yamls (see below).
  • Minimize the diff between each pair of versions. For example between lpuart_v1.yaml and lpuart_v2.yaml. If one is missing enums or descriptions, copy it from another.
  • Make sure the block
  • Add entries to perimap, see below.
  • Regen, check data/chips/*.yaml has the right block: lpuart_vX/LPUART fields

Please separate manual changes and changes resulting from regen in separate commits. It helps tremendously with review and rebasing/merging.

Register cleanup

SVDs have some widespread annoyances that should be fixed when adding register YAMLs to this repo. Check out chiptool transforms, they can help in speeding up the cleanups.

  • Remove "useless prefixes". For example if all regs in the RNG peripheral are named RNG_FOO, RNG_BAR, the RNG_ peripheral is not conveying any useful information at all, and must go.
  • Remove "useless enums". Useless enums is one of the biggest cause of slow compilation times in STM32 PACs.
    • 0=disabled, 1=enabled. Common in xxEN and xxIE fields. If a field says "enable foo" and is one bit, it's obvious "true" means enabled and "false" means disabled.
    • "Write 0/1 to clear" enums, common in xxIF fields.
    • Check out the DeleteEnums chiptool transforms.
  • Convert repeated registers or fields (like FOO0 FOO1, FOO2, FOO3) to arrays FOO[n].
    • Check out the MakeRegisterArray, MakeFieldArray chiptool transforms.

Adding support for a new family (RCC)

NOTE: At the time of writing all families are supported, so this is only useful in particular situations, for example if you want to regenerate an RCC register yaml from scratch.

Adding support for a new familiy is mostly a matter of adding support for RCC.

Now extract the RCC peripheral registers: ./d extract-all RCC --transform ./transform-RCC.yaml

Note that we have used a transform to mechanically clean up some of the RCC definitions. This will produce a YAML file for each chip model in ./tmp/RCC.

Sometimes the peripheral name will not match the name defined in the SVD files, check the SVD file for the correct peripheral name.

RCC registers are usually identical within a family, except they have different subsets of the enable/reset bits because different chips have different amounts of peripherals. (i.e. one particular bit position in one particular register is either present or not, but will never have different meanings in different chips of the same family.)

To verify they're indeed subsets, choose the model with the largest peripheral set possible (e.g. the STM32G081) and compare its YAML against each of the other models' to verify that they are all mutually consistent.

Finally, we can merge

./merge_regs.py tmp/RCC/g0*.yaml

This will produce regs_merged.yaml, which we can copy into its final resting place:

mv regs_merged.yaml data/registers/rcc_g0.yaml

To assign these newly generated registers to peripherals, utilize the mapping done in parse.py. An example mapping can be seen in the following snippet

('STM32G0.*:RCC:.*', 'rcc_g0/RCC'),

such mapping assignes the rcc_g0/RCC register block to the RCC peripheral in every device from the STM32G0 family.

Peripheral mapping (perimap)

The stm32-data-gen binary has a map to match peripherals to the right version in all chips, the perimap.

When parsing a chip, for each peripheral a "key" string is constructed using this format: CHIP:PERIPHERAL_NAME:IP_NAME:IP_VERSION, where:

  • CHIP: full chip name, for example STM32L443CC
  • PERIPHERAL_NAME: peripheral name, for example SPI3. Corresponds to IP.InstanceName in the MCU XML.
  • IP_NAME: IP name, for example SPI. Corresponds to IP.Name in the MCU XML.
  • IP_VERSION: IP version, for example spi2s1_v3_3_Cube, Corresponds to IP.Version in the MCU XML.

perimap entries are regexes matching on the above "key" string. First regex that matches wins.

The IP version is particularly useful. It is an ST-internal "IP version" that's incremented every time changes are made to the peripheral, so it correlates very well to changes in the peripheral's register interface.

You should prefer matching peripherals by IP version whenever possible. For example:

('.*:SPI:spi2s1_v2_2', 'spi_v1/SPI'),
('.*:SPI:spi2s1_v3_2', 'spi_v2/SPI'),

Sometimes it's not possible to map by IP version, and we have to map by chip name. For example:

('STM32H7.*:FLASH:.*', 'flash_h7/FLASH'),
('STM32F0.*:FLASH:.*', 'flash_f0/FLASH'),
('STM32F1.*:FLASH:.*', 'flash_f1/FLASH'),
('STM32F3.*:FLASH:.*', 'flash_f3/FLASH'),
('STM32F4.*:FLASH:.*', 'flash_f4/FLASH'),

Sometimes even the same IP name+version in the same chip family has different registers (different instances of the IP are configured differently), so we have to map by chip name AND peripheral instance name. This should be the last resort. For example:

('STM32F7.*:TIM1:.*', 'timer_v1/TIM_ADV'),
('STM32F7.*:TIM8:.*', 'timer_v1/TIM_ADV'),
('.*TIM\d.*:gptimer.*', 'timer_v1/TIM_GP16'),

Peripheral versions

The versions of peripherals can be found in the table here.