# STA Core library

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Collection of useful stuff.



# Modules


## Assert

Assertion handling.

Configuration:
* `#define STA_ASSERT_ENABLE`: Enable module
* `#define STA_ASSERT_DISABLE`: Forces module off when defined
* `#define STA_HALT <func_name>`: Override function called after failed asserts
* `DEBUG`: Automatically enables module when defined
* `NDEBUG`: Forces module off when defined

Both `sta::assert_failed` and `sta::assert_halt` provide weak definitions and
can be overridden by the application. `sta::assert_halt` is only called
via the **STA_HALT** macro which can also be provided by the application.

The default implementation of `sta::assert_failed` uses **STA_DEBUG_PRINT** internally
and will not generate any output if the **DEBUG_SERIAL** module is disabled.


## Debug Serial

Debug serial output macros.

Configuration:
* `#define STA_DEBUG_SERIAL_ENABLE`: Enable module
* `#define STA_DEBUG_SERIAL_FORCE`: Ignore debug defines and always enable output
* `DEBUG`: Enables output when defined
* `NDEBUG`: Disables output when defined (overrides DEBUG)

The `sta::DebugSerial` instance must be provided.


## Endian

Endian-ness conversion for multi-byte types.


## Enum Flags

Type for using enum values as combinable flags.


## Lang

Macros related to compiler features. Not actually part of the C/C++ language.


## MCU

Defines specific to different MCUs. Include the appropriate header from `sta/mcu`
for the MCU used by the application in the `<sta/config.hpp>` header. 


## Printf

Choose which `printf` implementation is used by STA libraries.

Configuration:
* `#define STA_PRINTF_USE_STDLIB`:  Use the stdlib implementation
* `#define STA_PRINTF_USE_MPALAND`: Use the implementation by Marco Paland (thread safe & reentrant)


## HAL Delay

HAL based delay functions.

Configuration:
* `#define STA_HAL_DELAY_ENABLE`: Enable module
* `#define STA_HAL_DELAY_US_TIM <tim_handle>`: 1 MHz TIM instance used by `sta::delayUs`

TIM time base must be started before using `sta::delayUs` by calling `sta::initHAL`.
When using the startup system task this is handled automatically.


## Interfaces

The intention of these interfaces is to provide an abstraction layer for commonly used
resources. Libraries using these interfaces can be reused on different platforms
by simply implementing the required interfaces for the selected platform.

Interfaces for the following resources are provided:
* GPIO pin
* Mutex
* Signal
* SPI
* UART


## HAL implementations

Implementations using the HAL are provided for the following interfaces:
* GpioPin
* SpiInterface, SpiDevice
* UART

To enable these implementations follow the instructions from the individual headers.


## Atomic implementations

Implementations using atomic variables are provided for the following interfaces:
* Mutex
* Signal

To enable these implementations define `STA_ATOMIC_ENABLE` in `<sta/config.hpp>`.