stm32-ada/README.md

stm32-ada

Ada bindings for STM32 internals

Design directions

Main design goal is a type safety. Specific enumerations and records are used in hardware definitions. Common structure of a peripherial module is a record with all its registers and every register is a record with all its fields. That is every field is addressed using scheme Unit.Register.Field

While it is generally preferred to have entities same identifiers as in STM's user manuals, it is not always possible. So some of them have originel or a bit changed name.

• The identifier clashes with Ada keyword. E. g. ABORT bit-field is renamed to ABRT.
• Identifier is not given by UM. This is common case for bit-field values. They taken descriptive names based on original UM text.
• Identifier decomposition and generalization. Bitfield identifiers are shortened if they have common part. Also if two or more registers have same or analogous fields they commonly share the same record type, thus having same field names. Thus RCC's xxxRST, xxxEN and xxxLPEN registers a defined the same with RST/EN/LPEN part removed from their bit fields.

Compiler implication

System.Address should be standard 32 bit byte address as in CPU registers and peripherals (DMA etc.).

Development boards supported

stm32f429disco (stm32f429disc1) -- board available from STM. 429disco in examples.

STM32F407Z-based board from PiSwords. Widely available from chinese suppliers. 407z_piswords in examples.

Hardware quirks and workarounds

APB

APB does not support partial writes to 32-bit registers. The library provides access to register fields as records. This could lead compiler to emit byte and half-word writes to APB registers causing erroneous effects. As a workaround those registers should be read to local variable, this variable altered, and then written back to the hardware. GNAT users may not need the workaround, because of its pragma Volatile_Full_Access used in this library.

Compiler specific notes

There are compiler-specific pragmas so your compiler may complain about them.

GNAT

Volatile_Full_Access pragma is used on (at least writable) APB registers as byte- and half-wide writes are not supported by APB. Read STM docs on what those accesses actually do.

Currently GPR cannot manage aggregate projects for different targets. GNU Make script is used to build whole set of libraries instead.