STM8 Microcontrollers – the Final Chapters

Hardware

One Wire (OW) – DS18B20

One Wire (OW) communication is not as much as popular as I2C, SPI or serial communication. However, there are a number of devices that use one-wire communication method. DS18B20 digital temperature sensor from Dallas is one such example. For OW communication, we do not need any special hardware. Only GPIO bit-banging is all that is needed. Additionally, we can use a timer if we do not want to use software-based delays.

 

Hardware Connection

OW-DS18B20

 

 

 

Code Example

one_wire.h

#include "STM8S.h"


#define DS18B20_port      GPIOD       
#define DS18B20_pin       GPIO_PIN_2

#define DS18B20_INPUT()   do{GPIO_DeInit(DS18B20_port); GPIO_Init(DS18B20_port, DS18B20_pin, GPIO_MODE_IN_FL_NO_IT);}while(0)
 
#define DS18B20_OUTPUT()  do{GPIO_DeInit(DS18B20_port); GPIO_Init(DS18B20_port, DS18B20_pin, GPIO_MODE_OUT_PP_HIGH_FAST);}while(0)

#define DS18B20_IN()      GPIO_ReadInputPin(DS18B20_port, DS18B20_pin)

#define DS18B20_OUT_LOW() GPIO_WriteLow(DS18B20_port, DS18B20_pin)
#define DS18B20_OUT_HIGH() GPIO_WriteHigh(DS18B20_port, DS18B20_pin)     


bool onewire_reset(void);
void onewire_write_bit(bool bit_value);
bool onewire_read_bit(void);
void onewire_write(unsigned char value);   
unsigned char onewire_read(void);

 

one_wire.c

#include "one_wire.h"


bool onewire_reset(void
{                                        
        bool res = FALSE;

        DS18B20_OUTPUT();                
        DS18B20_OUT_LOW();
        delay_us(480);       
        DS18B20_OUT_HIGH();
        delay_us(60);       

        DS18B20_INPUT();
        res = DS18B20_IN();
        delay_us(480);      

        return res;
}


void onewire_write_bit(bool bit_value)
{
       DS18B20_OUTPUT();
       DS18B20_OUT_LOW();

       if(bit_value)
       {    
              delay_us(104);
              DS18B20_OUT_HIGH();  
       }             
}    


bool onewire_read_bit(void)       
{    
       DS18B20_OUTPUT();
       DS18B20_OUT_LOW(); 
       DS18B20_OUT_HIGH(); 
       delay_us(15);     
       DS18B20_INPUT();

       return(DS18B20_IN());   
}


void onewire_write(unsigned char value)
{                   
        unsigned char s = 0;

        DS18B20_OUTPUT();

        while(s < 8)   
        {                             
                if((value & (1 << s)))
                {
                       DS18B20_OUT_LOW();
                       delay_cycles(1);  
                       DS18B20_OUT_HIGH(); 
                       delay_us(60);  
                }      

                else
                {
                      DS18B20_OUT_LOW();          
                       delay_us(60);          
                       DS18B20_OUT_HIGH();  
                       delay_cycles(1); 
                }
                s++;
        }
}                                     


unsigned char onewire_read(void)
{
        unsigned char s = 0x00;
        unsigned char value = 0x00;

        while(s < 8)
        {
                DS18B20_OUTPUT();

                DS18B20_OUT_LOW();
                delay_cycles(1);                 
                DS18B20_OUT_HIGH(); 

                DS18B20_INPUT();
                if(DS18B20_IN()) 
                {                                     
                    value |=  (1 << s);                        
                }       

                delay_us(60);     
                s++;
        }    

        return value;
}   

 

DS18B20.h

#include "STM8S.h"
#include "one_wire.h" 


#define convert_T          0x44
#define read_scratchpad   0xBE           
#define write_scratchpad  0x4E
#define copy_scratchpad   0x48  
#define recall_E2          0xB8
#define read_power_supply 0xB4   
#define skip_ROM           0xCC

#define resolution         12


void DS18B20_init(void);
float DS18B20_get_temperature(void);

DS18B20.c

#include "DS18B20.h"


void DS18B20_init(void)                            
{                                      
       onewire_reset();
       delay_ms(100);
}             


float DS18B20_get_temperature(void)
{                                              
       unsigned char msb = 0x00;
       unsigned char lsb = 0x00;
       register float temp = 0.0; 

       onewire_reset();    
       onewire_write(skip_ROM);       
       onewire_write(convert_T);

       switch(resolution)  
       {                                                 
              case 12:
              {                                              
                     delay_ms(750);
                     break;
              }               
              case 11:                                    
              {             
                     delay_ms(375);
                     break;
              }          
              case 10:                            
              {                                
                     delay_ms(188);  
                     break;
              }                                       
              case 9:                                  
              {                                               
                     delay_ms(94);                
                     break;                           
              }                       
       }                 

       onewire_reset();

       onewire_write(skip_ROM);                
       onewire_write(read_scratchpad);

       lsb = onewire_read();
       msb = onewire_read();

       temp = msb;                          
       temp *= 256.0;
       temp += lsb;


       switch(resolution)  
       {                                 
              case 12:           
              {                                               
                     temp *= 0.0625;                
                     break;                           
              }            
              case 11:
              {             
                     temp *= 0.125;     
                     break;
              }               
              case 10:
              {           
                     temp *= 0.25;      
                     break;
              } 
              case 9:                                
              {                                
                     temp *= 0.5;       
                     break;     
              }                         
       } 

       delay_ms(40);      

       return (temp);      
}

 

main.c

#include "STM8S.h"
#include "DS18B20.h"
#include "lcd.h"


unsigned char bl_state;
unsigned char data_value;

const unsigned char symbol[8] =
{
   0x00, 0x06, 0x09, 0x09, 0x06, 0x00, 0x00, 0x00
};


void clock_setup(void);
void GPIO_setup(void);
void lcd_symbol(void);
void print_C(unsigned char x_pos, unsigned char y_pos, signed int value);
void print_I(unsigned char x_pos, unsigned char y_pos, signed long value);
void print_D(unsigned char x_pos, unsigned char y_pos, signed int value, unsigned char points);
void print_F(unsigned char x_pos, unsigned char y_pos, float value, unsigned char points);


void main(void)
{            
       float temp = 0.0;

       clock_setup();
       GPIO_setup();

       DS18B20_init();

       LCD_init(); 
       LCD_clear_home();
       lcd_symbol();

       LCD_goto(0, 0);
       LCD_putstr("STM8 DS18B20 Ex.");

       LCD_goto(0, 1);
    LCD_putstr("T/ C");
    LCD_goto(2, 1);
    LCD_send(0, DAT);

       while(TRUE)
       {
              temp = DS18B20_get_temperature();
              print_F(9, 1, temp, 3);
              delay_ms(600);
       };
}


void clock_setup(void)
{
       CLK_DeInit();

       CLK_HSECmd(DISABLE);
       CLK_LSICmd(DISABLE);
       CLK_HSICmd(ENABLE);
       while(CLK_GetFlagStatus(CLK_FLAG_HSIRDY) == FALSE);

       CLK_ClockSwitchCmd(ENABLE);
       CLK_HSIPrescalerConfig(CLK_PRESCALER_HSIDIV1);
                                                                            CLK_SYSCLKConfig(CLK_PRESCALER_CPUDIV1);

       CLK_ClockSwitchConfig(CLK_SWITCHMODE_AUTO,
                             CLK_SOURCE_HSI,
                            DISABLE,
                            CLK_CURRENTCLOCKSTATE_ENABLE);

       CLK_PeripheralClockConfig(CLK_PERIPHERAL_I2C, ENABLE);
       CLK_PeripheralClockConfig(CLK_PERIPHERAL_SPI, DISABLE);
       CLK_PeripheralClockConfig(CLK_PERIPHERAL_ADC, DISABLE);
       CLK_PeripheralClockConfig(CLK_PERIPHERAL_AWU, DISABLE);
       CLK_PeripheralClockConfig(CLK_PERIPHERAL_UART1, DISABLE);
       CLK_PeripheralClockConfig(CLK_PERIPHERAL_TIMER1, DISABLE);
       CLK_PeripheralClockConfig(CLK_PERIPHERAL_TIMER2, DISABLE);
       CLK_PeripheralClockConfig(CLK_PERIPHERAL_TIMER4, DISABLE);
}


void GPIO_setup(void)
{
    GPIO_DeInit(DS18B20_port);
}


void lcd_symbol(void
{
   unsigned char s = 0; 

   LCD_send(0x40, CMD);

   for(s = 0; s < 8; s++)
   {
        LCD_send(symbol[s], DAT);
   }

   LCD_send(0x80, CMD);
}


void print_C(unsigned char x_pos, unsigned char y_pos, signed int value)
{
     unsigned char ch[5] = {0x20, 0x20, 0x20, 0x20, '\0'};

     if(value < 0x00)
     {
        ch[0] = 0x2D;
        value = -value;
     }
     else
     {
        ch[0] = 0x20;
     }

     if((value > 99) && (value <= 999))
     {
         ch[1] = ((value / 100) + 0x30);
         ch[2] = (((value % 100) / 10) + 0x30);
         ch[3] = ((value % 10) + 0x30);
     }
     else if((value > 9) && (value <= 99))
     {
         ch[1] = (((value % 100) / 10) + 0x30);
         ch[2] = ((value % 10) + 0x30);
         ch[3] = 0x20;
     }
     else if((value >= 0) && (value <= 9))
     {
         ch[1] = ((value % 10) + 0x30);
         ch[2] = 0x20;
         ch[3] = 0x20;
     }

        LCD_goto(x_pos, y_pos);
     LCD_putstr(ch);
}


void print_I(unsigned char x_pos, unsigned char y_pos, signed long value)
{
    unsigned char ch[7] = {0x20, 0x20, 0x20, 0x20, 0x20, 0x20, '\0'};

    if(value < 0)
    {
        ch[0] = 0x2D;
        value = -value;
    }
    else
    {
        ch[0] = 0x20;
    }

    if(value > 9999)
    {
        ch[1] = ((value / 10000) + 0x30);
        ch[2] = (((value % 10000)/ 1000) + 0x30);
        ch[3] = (((value % 1000) / 100) + 0x30);
        ch[4] = (((value % 100) / 10) + 0x30);
        ch[5] = ((value % 10) + 0x30);
    }

    else if((value > 999) && (value <= 9999))
    {
        ch[1] = (((value % 10000)/ 1000) + 0x30);
        ch[2] = (((value % 1000) / 100) + 0x30);
        ch[3] = (((value % 100) / 10) + 0x30);
        ch[4] = ((value % 10) + 0x30);
        ch[5] = 0x20;
    }
    else if((value > 99) && (value <= 999))
    {
        ch[1] = (((value % 1000) / 100) + 0x30);
        ch[2] = (((value % 100) / 10) + 0x30);
        ch[3] = ((value % 10) + 0x30);
        ch[4] = 0x20;
        ch[5] = 0x20;
    }
    else if((value > 9) && (value <= 99))
    {
        ch[1] = (((value % 100) / 10) + 0x30);
        ch[2] = ((value % 10) + 0x30);
        ch[3] = 0x20;
        ch[4] = 0x20;
        ch[5] = 0x20;
    }
    else
    {
        ch[1] = ((value % 10) + 0x30);
        ch[2] = 0x20;
        ch[3] = 0x20;
        ch[4] = 0x20;
        ch[5] = 0x20;
    }

    LCD_goto(x_pos, y_pos);
    LCD_putstr(ch);
}


void print_D(unsigned char x_pos, unsigned char y_pos, signed int value, unsigned char points)
{
    char ch[5] = {0x2E, 0x20, 0x20, '\0'};

    ch[1] = ((value / 100) + 0x30);

    if(points > 1)
    {
        ch[2] = (((value / 10) % 10) + 0x30);

              if(points > 1)
              {
                     ch[3] = ((value % 10) + 0x30);
              }
    }

    LCD_goto(x_pos, y_pos);
    LCD_putstr(ch);
}


void print_F(unsigned char x_pos, unsigned char y_pos, float value, unsigned char points)
{
    signed long tmp = 0x0000;

    tmp = value;
    print_I(x_pos, y_pos, tmp);
    tmp = ((value - tmp) * 1000);

    if(tmp < 0)
    {
       tmp = -tmp;
    }

    if(value < 0)
    {
        value = -value;
              LCD_goto(x_pos, y_pos);
        LCD_putchar(0x2D);
    }
    else
    {
        LCD_goto(x_pos, y_pos);
        LCD_putchar(0x20);
    }

    if((value >= 10000) && (value < 100000))
    {
        print_D((x_pos + 6), y_pos, tmp, points);
    }
    else if((value >= 1000) && (value < 10000))
    {
        print_D((x_pos + 5), y_pos, tmp, points);
    }
    else if((value >= 100) && (value < 1000))
    {
        print_D((x_pos + 4), y_pos, tmp, points);
    }
    else if((value >= 10) && (value < 100))
    {
        print_D((x_pos + 3), y_pos, tmp, points);
    }
    else if(value < 10)
    {
        print_D((x_pos + 2), y_pos, tmp, points);
    }
}

 

Explanation

One wire communication is detailed in these application notes from Maxim:

https://www.maximintegrated.com/en/app-notes/index.mvp/id/126

https://www.maximintegrated.com/en/app-notes/index.mvp/id/162

These notes are all that are needed for implementing the one wire communication interface for DS18B20. Please go through these notes. The codes are self-explanatory and are implemented from the code examples in these app notes.

 

 

Demo

DS18B20

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25 comments

  • Hey; thanks a lot for your prefect article, could you send me please the delay libraries I haven’t got the right version of them, I have an error about “delay_cycle()”.

    • STM8S_delay.h


      #include "stm8s.h"

      #define F_CPU 16000000UL
      #define dly_const (F_CPU / 16000000.0F)

      void delay_us(unsigned int value);
      void delay_ms(unsigned int value);

      STM8S_delay.c


      #include "stm8s_delay.h"

      void delay_us(unsigned int value)
      {
      register unsigned int loops = (dly_const * value) ;

      while(loops)
      {
      _asm ("nop");
      loops--;
      };
      }

      void delay_ms(unsigned int value)
      {
      while(value)
      {
      delay_us(1000);
      value--;
      };
      }

      I didn’t use delay cycle in my library…. Are you using some other compiler other than Cosmic + STVD?

  • Really outstanding library! Thanks for helping out. I am using the STM8AF5288 so made some changes and worked like a charm. but the issue i am facing right now is the font size. is there any available font library that could be replaced to get bigger fonts? and If possible can you explain how the font is being created on the ssd1306, I mean the way the pixels are being drawn using the hex code (in the font.h file).
    Thanks in advance.

  • Really outstanding library! Thanks for helping out. I am using the STM8AF5288 so made some changes and worked like a charm. but the issue i am facing right now is the font size. is there any available font library that could be replaced to get bigger fonts ? and If possible can you explain how the font is being created on the ssd1306, I mean the way the pixels are being drawn using the hex code (in the font.h file).
    Thanks in advance.

    • There are several OLED libraries available in the internet with big fonts but I’m happy with this font size to make maximum use of the display…. Thus I didn’t go for development of libraries with big fonts….

      • thanks for the quick reply, But the thing is that i am facing a issue with that of the draw bitmap function.
        i.e.
        void OLED_draw_bitmap(unsigned char xb, unsigned char yb, unsigned char xe, unsigned char ye, unsigned char *bmp_img)

        {

        unsigned int s = 0x0000;

        unsigned char x_pos = 0x00;

        unsigned char y_pos = 0x00;

        for(y_pos = yb; y_pos <= ye; y_pos++)

        {

        OLED_gotoxy(xb, y_pos);

        for(x_pos = xb; x_pos < xe; x_pos++)

        {

        OLED_write(bmp_img[s++], DAT);

        }

        }

        }

        and i am calling it by the following way:
        OLED_draw_bitmap(0,0,128,64,(unsigned char *)&image_data_LesInv);

        and my bitmap file goes like this:
        static const uint8_t image_data_LesInv[128][64] = {
        // 'untitled', 128x64px
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0x7f, 0x3f, 0x3f, 0x3f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f,
        0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f,
        0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f,
        0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x3f, 0x3f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0x01, 0x00, 0x00, 0x00, 0x00, 0xf8, 0xf8, 0xf8, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18,
        0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0xf8, 0xf8, 0xf8,
        0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8,
        0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x7f, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xf8, 0xf0, 0xe0, 0xe0, 0xe0, 0xe0, 0x00, 0x00, 0x00, 0x01, 0x07,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0x1f, 0x0f, 0x07, 0x07, 0x07, 0x07, 0x00, 0x00, 0x00, 0x80, 0xe0,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0x80, 0x00, 0x00, 0x00, 0x00, 0x1f, 0x1f, 0x1f, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18,
        0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18,
        0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x1f,
        0x1f, 0x1f, 0x1f, 0x1f, 0x1f, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xfe, 0xfc, 0xfc, 0xfc, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8,
        0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8,
        0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8,
        0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xf8, 0xfc, 0xfc, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
        };

        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        but the issue is that my image does gets generated but it gets back to blank screen within a 500ms or so.
        can you please help with the same.

        • void OLED_draw_bitmap(unsigned char xb, unsigned char yb, unsigned char xe, unsigned char ye, unsigned char *bmp_img)
          {
          unsigned int s = 0x0000;
          unsigned char x_pos = 0x00;
          unsigned char y_pos = 0x00;

          for(y_pos = yb; y_pos <= ye; y_pos++)
          {
          OLED_gotoxy(xb, y_pos);
          for(x_pos = xb; x_pos < xe; x_pos++)
          {
          OLED_write(bmp_img[s++], DAT);
          }
          }
          }

          This was the original code but yours seems to be modified in the for loops…. Please recheck unless it is intentional….

          • both the loops are the same. I did not make any changes in the original code but the bitmap image seems to get printed on the screen but it gets instantly blank within 20ms.
            can you help me for the same.
            Thanks in advance.

          • Could you send me the whole code? I think there is an overflow somewhere….

  • Hello,
    How can i change the font size so i can support for example [92][12] ? Saw some libraries on the net but i am not sure if they are compatible with this code… or am i doing something wrong ? I tried manipulating the current one with some cycles within ” OLED_print_char ” also chaning 0x06 to 0x0C with a font library also tried creating fonts but i did not get the expected result. Can you give me some advice please ?
    Thank you for your time!

    • The coordinates of the OLED displays are mapped as multiples of 8-bits or 8 dots in both x and y directions. So just by changing x-coordinate values won’t result in larger fonts…. You must also take care of the y-coordinate too…. Take the example of the bitmap function:

      void OLED_draw_bitmap(unsigned char xb, unsigned char yb, unsigned char xe, unsigned char ye, unsigned char *bmp_img)
      {
      unsigned int s = 0x0000;
      unsigned char x_pos = 0x00;
      unsigned char y_pos = 0x00;

      for(y_pos = yb; y_pos <= ye; y_pos++)
      {
      OLED_gotoxy(xb, y_pos);
      for(x_pos = xb; x_pos < xe; x_pos++)
      {
      OLED_write(bmp_img[s], DAT);
      s++;
      }
      }
      }

      It takes care of the y-coordinate part once the x-coordinate points are filled up….

  • Hi great tutorial!
    Can you post code for interfacing external eeprom using i2c for stm8s003f3??

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  • Outstanding bro. Carry on. Wish your good luck.

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