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Linux + wiringPi

Build library & examples using :

cd raspberry/linux-wiringpi
./run.sh

Library will be generated under out/libmetecdriver.so. Examples will be generated under out/examples.

You will have to copy the output files above on the Raspberry PI manually or write a script to do this (depending if you are using SSH, NFS...)

Write to multiple Braille cells

#include "braille.h"
#include "wiringPi.h"

using namespace MetecDriverLibrary;

#define CELL_COUNT 20
#define ON         3
#define DIN        7
#define STROBE     0
#define CLK        2
#define DOUT       1

#define PATTERN_LENGTH 14
uint16_t pattern[PATTERN_LENGTH] = {
    0x283a,  0x2811,  0x2807,  0x2809,  0x2815,  0x280d,  0x2811, 0x20,  0x2813, 0x2815, 0x280d, 0x2811, 0x20, 0x2816
//    ⠺         ⠑        ⠇        ⠉       ⠕        ⠍        ⠑             ⠓       ⠕       ⠍       ⠑             ⠖
//    W         E        L        C        O        M        E             H       O        M       E             !
};

MetecDriver metecDriver(CELL_COUNT, ON, DIN, STROBE, CLK, DOUT);

void setup() {
    wiringPiSetup();
    metecDriver.init();
    metecDriver.writeCells(pattern, PATTERN_LENGTH, false);
}

int main() {
    setup();
    return 0;
}

Write to single Braille cell

#include "braille.h"
#include "wiringPi.h"

using namespace MetecDriverLibrary;

#define CELL_COUNT 20
#define ON         3
#define DIN        7
#define STROBE     0
#define CLK        2
#define DOUT       1

#define PATTERN_LENGTH 11
uint16_t pattern[PATTERN_LENGTH] = {
    0x2813, 0x2811, 0x2807, 0x2807, 0x2815, 0x20, 0x283a, 0x2815, 0x2817, 0x2807, 0x2819
//     ⠓       ⠑      ⠇       ⠇       ⠕             ⠺       ⠕      ⠗       ⠇      ⠙
//     H       E      L       L        O             W       O       R      L       D
};
MetecDriver metecDriver(CELL_COUNT, ON, DIN, STROBE, CLK, DOUT);

void setup() {
    wiringPiSetup();
    metecDriver.init();
    for (uint8_t i = 0 ; i  < PATTERN_LENGTH; i++) {
        metecDriver.writeSingleCell(CELL_COUNT - 1 - i, pattern[i]);
    }
}

int main() {
    setup();
    return 0;
}

Get button events

#include "braille.h"
#include "wiringPi.h"
#include "stdio.h"

using namespace MetecDriverLibrary;

#define CELL_COUNT 20
#define ON         3
#define DIN        7
#define STROBE     0
#define CLK        2
#define DOUT       1

MetecDriver metecDriver(CELL_COUNT, ON, DIN, STROBE, CLK, DOUT);

void setup() {
    wiringPiSetup();
    metecDriver.init();
}

void loop() {
    metecDriver.checkButton();
    if (metecDriver.btn_update) {
        printf("button %d switched to %d\n", metecDriver.btn_position, metecDriver.btn_state);
        metecDriver.btn_update = false;
    }
    delay(50);
}

int main() {
    setup();
    while (1)
        loop();
    return 0;
}

Raspberry PI linux development environment

The build environment is using cmake (see this). The base environment is located in the submodule raspberry-dev which download the toolchain and setup scripts to build wiringpi using cmake

Start with cloning the repo :

cd project_dir
git submodule add git://github.com/bertrandmartel/metec-braille-driver.git
git submodule update --init --recursive

You will need to build you own CmakeLists.txt like this one, something like :

cmake_minimum_required(VERSION 3.0)
project(metecdriver LANGUAGES CXX VERSION 1.0)
set (CMAKE_CXX_STANDARD 11)
include(GNUInstallDirs)
add_library(metecdriver SHARED ./metec-braille-driver/src/braille.cpp ./metec-braille-driver/src/pch.cpp)
set_target_properties(metecdriver PROPERTIES
    VERSION ${PROJECT_VERSION}
    SOVERSION 1
    LIBRARY_OUTPUT_DIRECTORY out
    PUBLIC_HEADER ./metec-braille-driver/include/braille.h)
target_include_directories(braille PRIVATE ./metec-braille-driver/include)
set (WPI_PATH ./metec-braille-driver/raspberry/linux-wiringpi/raspberry-dev/wiringPi/wiringPi)
include_directories (include ${WPI_PATH})

#link wiringpi
find_library(WPI_LIB wiringPi HINTS ${WPI_PATH} NO_CMAKE_FIND_ROOT_PATH)
if(NOT WPI_LIB)
message(FATAL_ERROR "wiringPi library not found")
endif()

Add to this CMakeLists.txt your project files to be built

Then you can build this using this script :

cmake . -DCMAKE_TOOLCHAIN_FILE=./metec-braille-driver/raspberry/linux-wiringpi/raspberry-dev/toolchain.cmake
make

Building liblouis

If you want to link against liblouis, you can add to your CMakeLists.txt :

#link liblouis
set (LIBLOUIS_PATH ../liblouis/liblouis/.libs)
find_library(LOUIS_LIB louis HINTS ${LIBLOUIS_PATH} NO_CMAKE_FIND_ROOT_PATH)
if(NOT LOUIS_LIB)
message(FATAL_ERROR "liblouis library not found")
endif()

And to cross compile liblouis:

# cross compile liblouis
export PATH=$PATH:$PWD/metec-braille-driver/raspberry/linux-wiringpi/raspberry-dev/tools/arm-bcm2708/arm-rpi-4.9.3-linux-gnueabihf/bin

cd /metec-braille-driver/raspberry/liblouis
if [ ! -f configure ]; then
	./autogen.sh
fi
if [ ! -f Makefile ]; then
	./configure --host arm-linux-gnueabihf
fi
make

Note that liblouis will generate output library under metec-braille-driver/raspberry/liblouis/liblouis/.libs which you will need to copy to Raspberry PI. Also you need to copy the liblouis table directory under /usr/local/share/liblouis/tables in Raspberry PI check liblouis_install.sh script to install tables.

Maybe there is a better way to install liblouis but we can't just copy the liblouis directory and sudo make install on the Raspberry PI since some path are hardcoded in the configure step

Using liblouis with libmetecdriver

#include "braille.h"
#include "wiringPi.h"
#include <string>

#include "liblouis.h"
#include "internal.h"

using namespace MetecDriverLibrary;
using namespace std;

#define CELL_COUNT 20
#define ON         3
#define DIN        7
#define STROBE     0
#define CLK        2
#define DOUT       1

#define BRAILLE_TABLE "unicode.dis,en-gb-g1.utb"

int translateToBraille(string input, uint16_t *buffer, int* translen) {
    uint16_t inbuf[MAXSTRING];
    int inlen = _lou_extParseChars(input.c_str(), inbuf);
    return lou_translateString(BRAILLE_TABLE, inbuf, &inlen, buffer, translen, NULL, NULL, 0);
}

MetecDriver metecDriver(CELL_COUNT, ON, DIN, STROBE, CLK, DOUT);

int main() {
    wiringPiSetup();
    metecDriver.init();

    string input = "hello world !";

    uint16_t buffer[MAXSTRING];
    int translen = MAXSTRING;

    if (!translateToBraille(input, buffer, &translen)) {
        printf("failed to translate input to braille\n");
        return;
    }
    metecDriver.writeCells(buffer, CELL_COUNT, false);
    lou_free();
    return 0;
}

License

The MIT License (MIT) Copyright (c) 2018 Bertrand Martel