rtt

C++ implementation of the SEGGER Real Time Transfer (RTT) protocol. RTT is a protocol to transfer data beetween a microcontroller and a host computer with the use of a debugger.

The implemation is fully configurable at compile time and there is no runtime overhead¹ for the initialisation of the control blocks.

Usage

For the most basic usage see examples/static_buffers.cpp.

#include "rtt/rtt.hpp"
#include <string_view>

// basic configuration with 1 up buffer in skip mode with 512 bytes size.
using RttConfig = rtt::SingleModeUpOnlyEmptyNameConfig<rtt::BufferMode::skip, 512>;
using RttType   = rtt::ControlBlock<RttConfig>;

static inline constinit typename RttType::Storage_t storage{};
static inline constinit RttType                     rttControlBlock{storage};

int main() {
    static constexpr std::string_view msg{"test\n"};
    rttControlBlock.write<0>(msg);
}

There are more advanced usecases and configurations in the examples folder.

host application

For receiving the data on the host see segger website or openocd website.

cmake

To use this project in a cmake project, just add the rtt folder via add_subdirectory and link against it using target_link_libraries.

example:

  add_subdirectory(rtt)
  target_link_libraries(${target_name} rtt::rtt)

header only

You can also use rtt as single header. Just copy rtt.hpp wherever you need it.

buffer placement

To prevent zero initializing of the storage you can place it into a ram section which does not get initialized.

example:

[[gnu::section(".noInit")]] static inline constinit typename RttType::Storage_t rttStorage;

Contribution

Feel free to report bugs or submit pull requests.

Limitations

On systems with cache, the user needs to ensure that the storage and control blocks are aligned to cache lines.
Only ranges with contigues memory are supported. There is no reason, other then performace, to not support non contigues ranges. When there is a need for that, feel free to suggest an option how to configure it.

TODO

For Cortex-M7/M23/M33/A/R: There is a data memory barrier missing.

The control blocks will be inizialised in startup code while copying the data segment. There will be 24 + <number of buffers> * 24 bytes copied. ↩

dominicpoeschko/rtt

rtt