Frame-buffer header file on SD-card¶

The frame-buffer header file on SD-card library prints the frame-buffer of the screen as a header file on the serial console.

The header file is added to the source code and included in the project of the application statically at build-time. Once the application is built, it loads the image into the frame-buffer, ready to be displayed dynamically at run-time.

This option supports all the screens, monochrome and colour.

Info

This method is not recommended for MCUs, as the management of the SD-card is rather slow and prone to interferences.

The frame-buffer header file on SD-card library is available on the Commercial edition.

Configure¶

Warning

Ensure the screen is declared and initialised according to the configuration procedure.

#include "hV_File_Frame.h"

The pre-processor statement includes the file library. It should be mentioned after the statement for the screen library.

Danger

This library requires the external SD library to manage the SD-card.

Ensure the external SD library is installed and configured properly.

File_Frame myFile(&myScreen);

The constructor File_Frame() sets the link to the screen. It should be mentioned after the constructor of the screen.

uint8_t result = myFile.beginFileSystem(pinCS,
    portSPI,
    pinDetect,
    pinLevel);

if (result != RESULT_SUCCESS)
{
    hV_HAL_Serial_crlf();
    hV_HAL_log(LEVEL_CRITICAL, "SD-card error");
    hV_HAL_exit(0x01);
}

result = myFile.setFolder("Image");

beginFileSystem() checks an SD-card is available and initialises it.

The required parameter is

The first line sets the pin for selecting the SD-card.

It is easily provided with myScreen.getBoardPins().cardCS.

The optional parameters are

The second line sets the number of the SPI port, 0 by default;
The third line sets the pin for the detect signal, NOT_CONNECTED or -1 par default;
The fourth line sets the level of detect signal, LOW by default.

The function returns RESULT_SUCCESS if successful, RESULT_ERROR otherwise.

To obtain the pin for selecting the SD-card, use

uint8_t pinCardCS = myScreen.getBoardPins().cardCS;
uint8_t result = myFile.beginFileSystem(pinCardCS);

setFolder() sets the name of the folder for the files, and creates it if it does not exists.

By default, the files are located under the folder img.

The function returns RESULT_SUCCESS if successful, RESULT_ERROR otherwise.

Use¶

Generate¶

myFile.saveScreen("File_Frame");

saveScreen() saves the screen on the SD-card as a frame-buffer header file.

The required parameter is

The first line provides the name of the file without the .h extension.

The resulting header file is named File_Frame.h and contains the structure Buffer_Buffer.

The function returns RESULT_SUCCESS if successful, RESULT_ERROR otherwise.

uint8_t result = myFile.endFileSystem();

endFileSystem() closes the SD-card.

The function returns RESULT_SUCCESS if successful, RESULT_ERROR otherwise.

Display¶

// Image
#include "Buffer.h"

uint8_t result;
result = myFile.readScreen(Buffer_Buffer);
if (result == RESULT_SUCCESS)
{
    myScreen.flush();
    wait(4);
}

The application needs to include the header file previously generated.

readScreen() loads the image into the frame-buffer, ready to be displayed.

The header file can also be read with the Serial_Buffer object, from the 16-bit image implementation on the Serial library.

The function returns RESULT_SUCCESS if successful, RESULT_ERROR otherwise.

Example¶

This is the core of the code from example File_Write_Buffer.ino.

First, generate the header file.

void displayPrintSerial()
{
    // Initialise
    uint8_t result;
    result = myFile.beginFileSystem(5);
    if (result != RESULT_SUCCESS)
    {
        hV_HAL_log(LEVEL_ERROR, "SD-card error");
        hV_HAL_Serial_crlf();
        return;
    }

    myScreen.setOrientation(myOrientation);
    myScreen.selectFont(fontLarge);

    myScreen.clear();
    myScreen.gText(8, 8, "Header Buffer");
    myScreen.flushFast();

    // Write to SD-card
    result = mySerialImage.saveScreen("Buffer");
    wait(4);
}

The generated header file contains the frame-buffer as an array.

// Frame-buffer as header file generated by hV_Serial_Buffer

// SDK
#include "hV_HAL_Peripherals.h"

// Release
#ifndef HEADER_BUFFER_BUFFER_RELEASE
#define HEADER_BUFFER_BUFFER_RELEASE

static const uint8_t Buffer_Buffer[] =
{
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // v= 0
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // v= 1
    // ...
}
#endif // HEADER_BUFFER_BUFFER_RELEASE

The window uses rectangular coordinates.

Then, include the header file in the application and build it.

// Serial
#include "hV_Serial.h"

// Image
#include "Buffer.h"

void displayReadHeader()
{
    uint8_t result;

    myScreen.setOrientation(myOrientation);

    myScreen.clear();
    myScreen.gText(4, 4, "Reading the header back...");
    myScreen.flushFast();
    wait(4);

    // Read from MCU Flash
    myScreen.clear();
    result = myHeader.readScreen(Buffer_Buffer);
    if (result == RESULT_SUCCESS)
    {
        myScreen.flush();
        wait(4);
    }
}