OpenMPTL - C++ Microprocessor Template Library
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README.md

Introduction

OpenMPTL is a C++ template library for lowlevel access to microprocessor registers and peripherals. It provides classes for generic register access and peripheral resources management, as well as a simulation framework. It is fast and deterministic, ideal for real-time operating systems.

Key Features:

  • Simple and comprehensive declaration and usage of microprocessor register classes
  • Framework for generic resources declaration (e.g. auto-configuration of peripheral enable registers)
  • Automatic generation of interrupt handler tables from resources
  • Compile-Time errors on resource conflicts or wrong register access
  • Supports bit-band access to register bits for faster access times
  • Simulation framework, showing all lowlevel register access and allowing to implement reactions to specific register bits.

OpenMPTL benefits from the C++11 template metaprogramming features, is an header-only library and does not depend on RTTI, exceptions or any external library.

Official home page: https://digint.ch/openmptl

Supported Architechtures

OpenMPTL provides generic functionality for the ARM Cortex family, as well as specific implementations for STM32 microcontrollers.

openmptl-reg-arm-cortex

Register declarations for many ARM Cortex microcontrollers are available, but not yet streamlined:

https://github.com/digint/openmptl-reg-arm-cortex

Documentation

The documentation is provided within the source code. The API Reference Documentation is available for online browsing.

Recommended starting points for high-level usage:

  • projects/stm32f4discovery-ledtest/src/ledtest.cpp
  • projects/stm32f4discovery/src/kernel.hpp
  • projects/stm32f4discovery/src/kernel.cpp
  • projects/stm32f4discovery/src/startup.hpp
  • drivers/joystick/stm32f103stk/joystick.hpp

Recommended starting points for low-level usage:

  • arch/arm/cortex/stm32/common/usart.hpp
  • include/register.hpp
  • include/register_access.hpp

Example usage (high level)

#include <arch/gpio.hpp>
using led_green = mptl::gpio_led< 'D', 12 >;
led_green::on();

Example usage (low level)

#include <arch/reg/spi.hpp>
using SPIx = SPI<1>;
auto reg = SPIx::CR1::load();
reg &= SPIx::CR1::SPE::value | SPIx::CR1::CRCNEXT::value | SPIx::CR1::CRCEN::value;
SPIx::CR1::store(reg);

A load() call results in:

constexpr volatile T * value_ptr = reinterpret_cast<volatile T *>(addr);
auto reg = *value_ptr;

A store() call results in:

*value_ptr = reg;

Where:

  • addr (constexpr) holds the non-pointer-type address of SPIx::CR1
  • T is the register type (e.g. uint32_t or uint8_t)

Simulation Framework

The simulation framework allows you to run embedded code in a simulated environment. It traces every register access and allows you to react on specific bit changes.

Example (ledtest)

# cd projects/stm32f4discovery-ledtest
# make SIMULATION=1
# ./stm32f4discovery-ledtest
<...>
RCC::CR         ::bitset()    0x00010000   [ ........ .......1 ........ ........ ]
[INFO] reacting to RCC::CR::HSEON, by setting RCC::CR::HSERDY
RCC::CR         ##bitset()    0x00020000   [ ........ ......1. ........ ........ ]
<...>
RCC::AHB1ENR    ::bitset()    0x00000008   [ ........ ........ ........ ....1... ]
GPIOD::MODER    ::load()      0x00000000   [ 00000000 00000000 00000000 00000000 ]
GPIOD::MODER    ::store()     0x01000000   [ 00000001 00000000 00000000 00000000 ]
GPIOD::BSRR     ::store()     0x00001000   [ 00000000 00000000 00010000 00000000 ]

Example (stm32f103stk-demo)

# cd projects/stm32f103stk-demo
# make SIMULATION=1
# ../../bin/sim_terminal.sh ./stm32f103stk-demo
<...>
Welcome to OpenMPTL terminal console!
# help
List of commands:
   cpuid      prints SCB::CPUID register hexadecimal value
   heap       allocate (leak) 1k on heap
   nrf        test the NRF24L01 chip (spi)

Folder Hierarchy

  • arch: Architecture dependent template library
  • bin: Helper applications
  • config: Makefiles, included by projects
  • doc: doxygen documentation build root
  • drivers: Drivers for specific peripherals
  • include: Main OpenMPTL class declarations
  • lib: Auxiliary libraries
  • projects: Example projects
    • stm32f103stk-demo: Example project for the stm32f103stk evaluation board
    • stm32f4discovery: Example project for the stm32f4discovery evaluation board
    • stm32f4discovery-ledtest: Simple example for the stm32f4discovery evaluation board
    • unittest: OpenMPTL unit tests
  • sim: Compilation units for simulation framework

Development

Source Code Repository

The source code for OpenMPTL is managed using Git.

Official repository:

git clone https://dev.tty0.ch/openmptl.git

Mirror on GitHub:

git clone https://github.com/digint/openmptl.git

How to Contribute

Your contributions are welcome!

If you would like to contribute or have found bugs:

Any feedback is appreciated!

License

OpenMPTL is free software, available under the GNU General Public License, Version 3.

Some register definition files in arch/*/reg contain derivative representations of CMSIS System View Description (SVD) files, and are subject to the "End User License Agreement for STMicroelectronics" (see "STM_License.html" in the containing directory).