ILI9341 + SPI + BluePill

1

Hello everyone!

I’m experiencing some problems with interfacing ILI9341 screen in SPI mode with BluePill (STM32F103C8T6 devboard) with mbed framework.

Libraries:

  1. for ILI9341 : SPI_TFT_ILI9341 - Lib for the new LCD Display with ILI9341 controll… | Mbed
  2. fonts : TFT_fonts - Font to use with the SPI_TFT lib | Mbed

Code:

#include "stdio.h"
#include "mbed.h"

#include "SPI_TFT_ILI9341.h"    // https://os.mbed.com/users/dreschpe/code/SPI_TFT_ILI9341/

#include "string"

#include "Arial12x12.h"         // All fonts were installe with library: 
#include "Arial24x23.h"         // https://os.mbed.com/users/dreschpe/code/TFT_fonts/
#include "Arial28x28.h"
#include "font_big.h"

// Pins for SPI1 on BluePill devboard
SPI_TFT_ILI9341 TFT(PA_7, PA_6, PA_5, PB_14, PB_13, PB_12,"TFT"); // mosi, miso, sclk, cs, reset, dc
 
int main()
{
    int i;

    TFT.claim(stdout);          // send stdout to the TFT display

    TFT.background(Black);      // set background to black
    TFT.foreground(White);      // set chars to white
    TFT.cls();                  // clear the screen
 
    TFT.background(Black);
    TFT.cls();
 
    TFT.set_orientation(1);
    TFT.set_font((unsigned char*)Arial24x23);
    TFT.locate(50,100);
    TFT.printf("TFT orientation");    
    
    TFT.set_font((unsigned char*)Arial12x12);

    for (int orientation = 1; orientation < 4 ; orientation++){
        TFT.set_orientation(orientation);
        TFT.locate(0,0);
        TFT.printf("   Hello Mbed %d", orientation);
    };
 
    // draw some graphics
    TFT.cls();
    TFT.set_font((unsigned char*)Arial24x23);
    TFT.locate(100,100);
    TFT.printf("Graphic");
 
    TFT.line(0,0,100,0,Green);
    TFT.line(0,0,0,200,Green);
    TFT.line(0,0,100,200,Green);
 
    TFT.rect(100,50,150,100,Red);
    TFT.fillrect(180,25,220,70,Blue);
 
    TFT.circle(80,150,33,White);
    TFT.fillcircle(160,190,20,Yellow);
 
    double s;
 
    for (i=0; i<320; i++) {
        s =20 * sin((long double) i / 10 );
        TFT.pixel(i,100 + (int)s ,Red);
    }
 
 
    wait(5);        // wait two seconds
 
    // bigger text
    TFT.foreground(White);
    TFT.background(Blue);
    TFT.cls();
    TFT.set_font((unsigned char*)Arial24x23);
    TFT.locate(0,0);
    TFT.printf("Different Fonts :");
 
    TFT.set_font((unsigned char*)Neu42x35);
    TFT.locate(0,30);
    TFT.printf("Hello Mbed 1");
    TFT.set_font((unsigned char*)Arial24x23);
    TFT.locate(20,80);
    TFT.printf("Hello Mbed 2");
    TFT.set_font((unsigned char*)Arial12x12);
    TFT.locate(35,120);
    TFT.printf("Hello Mbed 3");
    wait(5);
 
    // mbed logo
    TFT.background(Black);
    TFT.cls();
 
    TFT.locate(10,10);
    TFT.printf("Graphic from Flash");
 
    wait(5);
    TFT.cls();
    TFT.locate(10,10);
    TFT.printf("Graphic from File System");
    TFT.locate(10,20);
    TFT.printf("open test.bmp");
    int err = TFT.BMP_16(20,50,"test.bmp");
    if (err != 1) TFT.printf(" - Err: %d",err);
}

Errors:

In file included from src\main.cpp:8:0:
C:\Users\Yehor\.platformio\lib\TFT_fonts_ID284/Arial12x12.h:8:8: error: expected constructor, destructor, or type conversion before '(' token
__align(2)
^
In file included from src\main.cpp:9:0:
C:\Users\Yehor\.platformio\lib\TFT_fonts_ID284/Arial24x23.h:10:8: error: expected constructor, destructor, or type conversion before '(' token
__align(2)
^
In file included from src\main.cpp:10:0:
C:\Users\Yehor\.platformio\lib\TFT_fonts_ID284/Arial28x28.h:10:8: error: expected constructor, destructor, or type conversion before '(' token
__align(2)
^
In file included from src\main.cpp:11:0:
C:\Users\Yehor\.platformio\lib\TFT_fonts_ID284/font_big.h:10:8: error: expected constructor, destructor, or type conversion before '(' token
__align(2)
^
src\main.cpp: In function 'int main()':
src\main.cpp:30:34: error: 'Arial24x23' was not declared in this scope
TFT.set_font((unsigned char*)Arial24x23);
^~~~~~~~~~
src\main.cpp:34:34: error: 'Arial12x12' was not declared in this scope
TFT.set_font((unsigned char*)Arial12x12);
^~~~~~~~~~
src\main.cpp:76:34: error: 'Neu42x35' was not declared in this scope
TFT.set_font((unsigned char*)Neu42x35);
^~~~~~~~
*** [.pioenvs\bluepill_f103c8\src\main.o] Error 1

Please, help me to fix those errors.

The actual screen:

9341breakout
9341breakout707×600 150 KB

P.S. Fonts were installed with “TFT_fonts” library and they are declared in following files:

  • Arial12x12 : Arial12x12.h
  • Neu42x35 : big_font.h
  • Arial24x23 : Arial24x23.h
    which are included, based on first 3 errors.
2

found a solution:
all font files begin with:

__align(2)
const unsigned char FontName []= {... symbols ...}

everything started working after removal of “__align(2)” in file.
After that - another problem appears : limited flash size (not enough for storing 4 fonts, Bluepill has enough for storing 2 fonts only), but it is not a big deal.

Can anyone explain me what was the “__align(2)” for?

3

A compiler attribute to align the memory start address of that variable at 2-byte boundary.

Some MCU architecture require some memory to be aligned in some special cases like memory operations or transfers… It’s all different per architecture… I didn’t look into the code but I guess that __align(2) evaluates to __attribute__ ((aligned (2))) (see Using the GNU Compiler Collection (GCC))

4

So, if it was supposed to be there, should I return the __align(2) back, but rearranging?

from this:

__align(2)
const unsigned char FontName []= {... symbols ...}

to anything else?

This: didn’t work:

const unsigned char FontName []= {... symbols ...}  __attribute__ ((aligned (2)));

as well as this:

const unsigned char FontName []= {... symbols ...};
FontName [] __attribute__ ((aligned (2)));