Hi team! I am working on the OLED interfacing with STM32F103C8T6. All I want to do that is to display the counter value from 0 to 255 on OLED. But when I simply put the random number such as 48 it shows its equivalent ASCII value not a decimal value.

[jtron.1]

Hi team! I am working on the OLED interfacing with STM32F103C8T6. All I want to do that is to display the counter value from 0 to 255 on OLED. But when I simply put the random number such as 48 it shows its equivalent ASCII value not a decimal value as it is 48.

What is the reason of it?

I am delighted to ST community for the help.

Thanks in advance.

[Tesla DeLorean]

You've stated the symptoms twice, not sure that helps understand the cause.

Code is broken.

Show code.​

[jtron.1]

Thanks for the reply tesla.

Actually the problem is OLED shows ASCII value of decimal equivalent.

Below is the code

 //This function put the value that we want to display in my case i is the int and i=5(val) lets say

 int SSD1306_PutVal(int val, FontDef_t* Font, SSD1306_COLOR_t color) {

/* Write characters */

while (val) {

/* Write character by character */

if (SSD1306_PutV1(val, Font, color) != val) {

/* Return error */

return val;

}

/* Increase string pointer */

val++;

}

/* Everything OK, zero should be returned */

return val;

} 

//This function decide its Height and Width

int SSD1306_PutV1(int ch, FontDef_t* Font, SSD1306_COLOR_t color) {

uint32_t i, b, j;

/* Check available space in LCD */

if (

SSD1306_WIDTH <= (SSD1306.CurrentX + Font->FontWidth) ||

SSD1306_HEIGHT <= (SSD1306.CurrentY + Font->FontHeight)

) {

/* Error */

return 0;

}

/* Go through font */

for (i = 0; i < Font->FontHeight; i++) {

b = Font->data[(ch - 32) * Font->FontHeight + i];

for (j = 0; j < Font->FontWidth; j++) {

if ((b << j) & 0x8000) {

SSD1306_DrawPixel(SSD1306.CurrentX + j, (SSD1306.CurrentY + i), (SSD1306_COLOR_t) color);

} else {

SSD1306_DrawPixel(SSD1306.CurrentX + j, (SSD1306.CurrentY + i), (SSD1306_COLOR_t)!color);

}

}

}

/* Increase pointer */

SSD1306.CurrentX += Font->FontWidth;

/* Return character written */

return ch;

}

void SSD1306_UpdateScreen(void) {

uint8_t m;

for (m = 0; m < 8; m++) {

SSD1306_WRITECOMMAND(0xB0 + m); //Set Page Start

                   //Address for Page

                   //Addressing Mode

SSD1306_WRITECOMMAND(0x00);

SSD1306_WRITECOMMAND(0x10);

/* Write multi data */

ssd1306_I2C_WriteMulti(SSD1306_I2C_ADDR, 0x40, &SSD1306_Buffer[SSD1306_WIDTH * m], SSD1306_WIDTH);

}

}

void ssd1306_I2C_WriteMulti(uint8_t address, uint8_t reg, uint8_t* data, uint16_t count) {

uint8_t dt[256];

dt[0] = reg;

uint8_t i;

for(i = 0; i < count; i++)

dt[i+1] = data[i];

HAL_I2C_Master_Transmit(&hi2c1, address, dt, count+1, 10);

}

 //All the functions used below already described above

  int i;

  i=48;//When I put this value OLED shows its equivalent ASCII vale from 0123456789:

  SSD1306_GotoXY (0,0);// //function is above described

  SSD1306_PutVal ( i, &Font_11x18, 1);// //function is above described

  SSD1306_UpdateScreen(); //function is above described

  HAL_Delay (1000);

Thanks in advance.

 

[Tesla DeLorean]

PutVal function does not convert to a numeric value.

​

I​s this something you wrote or copied?

Perhaps rewrite so it does what it should.​

​

[jtron.1]

ohk got it.

I am going make changes as per our discussion and will let you know soon.

[jtron.1]

As I am working keil and the below function but keil shows a warning

(warning: implicit declaration of function 'simple_decimal_string' is invalid in C99 [-Wimplicit-function-declaration])

1. char *simple_decimal_string(unsigned int x) // convert 32-bit unsigned to decimal string
2. {
3. static char str[16]; // Enough to hold 10 digits and NUL
4. char *s = str + sizeof(str);
5.  
6. *--s = 0; // NULL at end, working backward
7. do
8. {
9. *--s = '0' + (x % 10);
10. x /= 10;
11. }
12. while(x);
13.  
14. return(s);
15. }

Then I started working on CUBE IDE.

In which I am facing a problem my code programmed in mcu but controller does not response like nothing burned in it.

I am using STM32F103C6 controller.

I am using ST-Link/V2 probe for programming.

Even I tried a simple blinky programme but it does not work.

I am using Debugger setting as OPEN OCD mode and software reset.

For led blinking I did following setting in CUBE MX.

Used SYS as serial wire

GPIO as output PC13 for led.

Using ext osc.

I wrote code simple for toggling led status.

HAL_GPIO_TogglePin(GPIOC,GPIO_PIN_13);

HAL_Delay(500);

[Tesla DeLorean]

>>warning: implicit declaration of function 'simple_decimal_string' is invalid in C99 [-Wimplicit-function-declaration]

So you used the function earlier in the code than the definition/body of the code?

[jtron.1]

Hi DeLorean.!

I am very happy to say that my code is working now.

Thank you so much tesla. This happens only with your guidance.

I also thanks to ST community for this platform.

Grateful.....!!!!!!!!!!!

Thanks a lot tesla again.

Actually I was declaring function body/definition not in the same file.

However, it is working.