Typesafe Register Usage

This project is based on Lefticus - cpp_starter_project

Prerequisites

• install cmsis_svd with python3 -m pip install -U -e 'git+https://github.com/posborne/cmsis-svd.git#egg=cmsis-svd&subdirectory=python'

General

This project will generate typesafe Register access which will be generated through a jinja template and generates header for each peripheral defined in the .svd files. It also allows the compile time check what access rights it has.

Setup

Setup CMake variable for chip family including the file extension .svd that you will use. For a list of files have a look at the data folder at cmsis_svd data

Usage

STMicro Example

STMicro: main.cpp can be found in the example directory.

#include <CRC.hpp>
#include <DCMI.hpp>
#include <RNG.hpp>
#include <fmt/format.h>

int main()
{
    fmt::print("CRC::DR.read():{0}\n", CRC::DR.read<decltype(CRC::BitFields::DR)>());
    fmt::print("RNG::SR.read():{0}\n", RNG::SR.read<decltype(RNG::BitFields::DRDY)>());
    fmt::print("RNG::SR():{0}\n", RNG::SR());
    DCMI::ICR |= DCMI::BitFields::ERR_ISC | DCMI::BitFields::FRAME_ISC;
    //fmt::print("DCMI::ICR():{0}\n", DCMI::ICR()); // compile error because it can't be read
    // dump register map
    DCMI::CR.dump();
    return static_cast<int>(RNG::SR());
}

Example output for STM32F20x.svd

CRC::DR.read():4294967295
RNG::SR.read():0
RNG::SR():0
Register name:      CR
|-----------------------------------------|
|      CAPTURE               R/W          | <-- Bit 0
|-----------------------------------------|
|         CM                 R/W          | <-- Bit 1
|-----------------------------------------|
|        CROP                R/W          | <-- Bit 2
|-----------------------------------------|
|        JPEG                R/W          | <-- Bit 3
|-----------------------------------------|
|        ESS                 R/W          | <-- Bit 4
|-----------------------------------------|
|       PCKPOL               R/W          | <-- Bit 5
|-----------------------------------------|
|       HSPOL                R/W          | <-- Bit 6
|-----------------------------------------|
|       VSPOL                R/W          | <-- Bit 7
|-----------------------------------------|
|        FCRC                R/W          | <-- Bit 8 - 9
|                                         |
|-----------------------------------------|
|        EDM                 R/W          | <-- Bit 10 - 11
|                                         |
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 12
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 13
|-----------------------------------------|
|       ENABLE               R/W          | <-- Bit 14
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 15
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 16
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 17
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 18
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 19
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 20
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 21
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 22
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 23
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 24
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 25
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 26
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 27
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 28
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 29
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 30
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 31
|-----------------------------------------|

Nordic Example

Nordic: main.cpp can be found in the example directory.

#include <TIMER0_S.hpp>
#include <fmt/format.h>

int main()
{
    fmt::print("TIMER0_S::BITMODE():{0}\n", TIMER0_S::BITMODE());
    // dump register map
    TIMER0_S::SHORTS.dump();
    return 0;
}

Example output for nrf9160.svd

TIMER0_S::BITMODE():0
Register name:    SHORTS
|-----------------------------------------|
|   COMPARE0_CLEAR           R/W          | <-- Bit 0
|-----------------------------------------|
|   COMPARE1_CLEAR           R/W          | <-- Bit 1
|-----------------------------------------|
|   COMPARE2_CLEAR           R/W          | <-- Bit 2
|-----------------------------------------|
|   COMPARE3_CLEAR           R/W          | <-- Bit 3
|-----------------------------------------|
|   COMPARE4_CLEAR           R/W          | <-- Bit 4
|-----------------------------------------|
|   COMPARE5_CLEAR           R/W          | <-- Bit 5
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 6
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 7
|-----------------------------------------|
|   COMPARE0_STOP            R/W          | <-- Bit 8
|-----------------------------------------|
|   COMPARE1_STOP            R/W          | <-- Bit 9
|-----------------------------------------|
|   COMPARE2_STOP            R/W          | <-- Bit 10
|-----------------------------------------|
|   COMPARE3_STOP            R/W          | <-- Bit 11
|-----------------------------------------|
|   COMPARE4_STOP            R/W          | <-- Bit 12
|-----------------------------------------|
|   COMPARE5_STOP            R/W          | <-- Bit 13
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 14
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 15
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 16
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 17
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 18
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 19
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 20
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 21
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 22
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 23
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 24
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 25
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 26
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 27
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 28
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 29
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 30
|-----------------------------------------|
|      Reserved              N/A          | <-- Bit 31
|-----------------------------------------|

Features

• C++20 features like concepts
• Typesafe access of registers
• Register defines can't be mixed up, e.g one define for another register
• Supports many chip families, see cmsis-svd
• Code generation will create files for development machines and embedded devices, easier write of unit tests
• Dump generated register values , see example output above

Size Comparison

• Windows / Linux development

  This will result in larger files because of the possibility of dumping the registers.

• MCU development

main:                                   # @main
        or      byte ptr [rip + DCMI::ICR (.0)], 21
        mov     rax, qword ptr [rip + RNG::CR (.0)]
        or      rax, 12
        mov     qword ptr [rip + RNG::CR (.0)], rax
        and     eax, 2147483647
        ret

To-Do

• generate tests for all peripherals
• remove duplicate code in CMake