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.

[jtron.1]

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

Why subtracting 32. This is an array when I simply write the value more than 32 OLED shows first element of an array.

Also I have seen an array used for RAM.

const uint16_t Font11x18 [] = {

0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,  // sp

0x0000, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0000, 0x0C00, 0x0C00, 0x0000, 0x0000, 0x0000,  // !

0x0000, 0x1B00, 0x1B00, 0x1B00, 0x1B00, 0x1B00, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,  // "

0x0000, 0x1980, 0x1980, 0x1980, 0x1980, 0x7FC0, 0x7FC0, 0x1980, 0x3300, 0x7FC0, 0x7FC0, 0x3300, 0x3300, 0x3300, 0x3300, 0x0000, 0x0000, 0x0000,  // #

0x0000, 0x1E00, 0x3F00, 0x7580, 0x6580, 0x7400, 0x3C00, 0x1E00, 0x0700, 0x0580, 0x6580, 0x6580, 0x7580, 0x3F00, 0x1E00, 0x0400, 0x0400, 0x0000,  // $

0x0000, 0x7000, 0xD800, 0xD840, 0xD8C0, 0xD980, 0x7300, 0x0600, 0x0C00, 0x1B80, 0x36C0, 0x66C0, 0x46C0, 0x06C0, 0x0380, 0x0000, 0x0000, 0x0000,  // %

0x0000, 0x1E00, 0x3F00, 0x3300, 0x3300, 0x3300, 0x1E00, 0x0C00, 0x3CC0, 0x66C0, 0x6380, 0x6180, 0x6380, 0x3EC0, 0x1C80, 0x0000, 0x0000, 0x0000,  // &

0x0000, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,  // '

0x0080, 0x0100, 0x0300, 0x0600, 0x0600, 0x0400, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0400, 0x0600, 0x0600, 0x0300, 0x0100, 0x0080,  // (

0x2000, 0x1000, 0x1800, 0x0C00, 0x0C00, 0x0400, 0x0600, 0x0600, 0x0600, 0x0600, 0x0600, 0x0600, 0x0400, 0x0C00, 0x0C00, 0x1800, 0x1000, 0x2000,  // )

0x0000, 0x0C00, 0x2D00, 0x3F00, 0x1E00, 0x3300, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,  // *

0x0000, 0x0000, 0x0000, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0xFFC0, 0xFFC0, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,  // +

0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0C00, 0x0C00, 0x0400, 0x0400, 0x0800,  // ,

0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x1E00, 0x1E00, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,  // -

0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0C00, 0x0C00, 0x0000, 0x0000, 0x0000,  // .

0x0000, 0x0300, 0x0300, 0x0300, 0x0600, 0x0600, 0x0600, 0x0600, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x1800, 0x1800, 0x1800, 0x0000, 0x0000, 0x0000,  // /

0x0000, 0x1E00, 0x3F00, 0x3300, 0x6180, 0x6180, 0x6180, 0x6D80, 0x6D80, 0x6180, 0x6180, 0x6180, 0x3300, 0x3F00, 0x1E00, 0x0000, 0x0000, 0x0000,  // 0

0x0000, 0x0600, 0x0E00, 0x1E00, 0x3600, 0x2600, 0x0600, 0x0600, 0x0600, 0x0600, 0x0600, 0x0600, 0x0600, 0x0600, 0x0600, 0x0000, 0x0000, 0x0000,  // 1

0x0000, 0x1E00, 0x3F00, 0x7380, 0x6180, 0x6180, 0x0180, 0x0300, 0x0600, 0x0C00, 0x1800, 0x3000, 0x6000, 0x7F80, 0x7F80, 0x0000, 0x0000, 0x0000,  // 2

0x0000, 0x1C00, 0x3E00, 0x6300, 0x6300, 0x0300, 0x0E00, 0x0E00, 0x0300, 0x0180, 0x0180, 0x6180, 0x7380, 0x3F00, 0x1E00, 0x0000, 0x0000, 0x0000,  // 3

0x0000, 0x0600, 0x0E00, 0x0E00, 0x1E00, 0x1E00, 0x1600, 0x3600, 0x3600, 0x6600, 0x7F80, 0x7F80, 0x0600, 0x0600, 0x0600, 0x0000, 0x0000, 0x0000,  // 4

0x0000, 0x7F00, 0x7F00, 0x6000, 0x6000, 0x6000, 0x6E00, 0x7F00, 0x6380, 0x0180, 0x0180, 0x6180, 0x7380, 0x3F00, 0x1E00, 0x0000, 0x0000, 0x0000,  // 5

0x0000, 0x1E00, 0x3F00, 0x3380, 0x6180, 0x6000, 0x6E00, 0x7F00, 0x7380, 0x6180, 0x6180, 0x6180, 0x3380, 0x3F00, 0x1E00, 0x0000, 0x0000, 0x0000,  // 6

0x0000, 0x7F80, 0x7F80, 0x0180, 0x0300, 0x0300, 0x0600, 0x0600, 0x0C00, 0x0C00, 0x0C00, 0x0800, 0x1800, 0x1800, 0x1800, 0x0000, 0x0000, 0x0000,  // 7

0x0000, 0x1E00, 0x3F00, 0x6380, 0x6180, 0x6180, 0x2100, 0x1E00, 0x3F00, 0x6180, 0x6180, 0x6180, 0x6180, 0x3F00, 0x1E00, 0x0000, 0x0000, 0x0000,  // 8

0x0000, 0x1E00, 0x3F00, 0x7300, 0x6180, 0x6180, 0x6180, 0x7380, 0x3F80, 0x1D80, 0x0180, 0x6180, 0x7300, 0x3F00, 0x1E00, 0x0000, 0x0000, 0x0000,  // 9

0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0C00, 0x0C00, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0C00, 0x0C00, 0x0000, 0x0000, 0x0000,  // :

0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0C00, 0x0C00, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0C00, 0x0C00, 0x0400, 0x0400, 0x0800,  // ;

0x0000, 0x0000, 0x0000, 0x0000, 0x0080, 0x0380, 0x0E00, 0x3800, 0x6000, 0x3800, 0x0E00, 0x0380, 0x0080, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,  // <

0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x7F80, 0x7F80, 0x0000, 0x0000, 0x7F80, 0x7F80, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,  // =

0x0000, 0x0000, 0x0000, 0x0000, 0x4000, 0x7000, 0x1C00, 0x0700, 0x0180, 0x0700, 0x1C00, 0x7000, 0x4000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,  // >

0x0000, 0x1F00, 0x3F80, 0x71C0, 0x60C0, 0x00C0, 0x01C0, 0x0380, 0x0700, 0x0E00, 0x0C00, 0x0C00, 0x0000, 0x0C00, 0x0C00, 0x0000, 0x0000, 0x0000,  // ?

0x0000, 0x1E00, 0x3F00, 0x3180, 0x7180, 0x6380, 0x6F80, 0x6D80, 0x6D80, 0x6F80, 0x6780, 0x6000, 0x3200, 0x3E00, 0x1C00, 0x0000, 0x0000, 0x0000,  // @

0x0000, 0x0E00, 0x0E00, 0x1B00, 0x1B00, 0x1B00, 0x1B00, 0x3180, 0x3180, 0x3F80, 0x3F80, 0x3180, 0x60C0, 0x60C0, 0x60C0, 0x0000, 0x0000, 0x0000,  // A

0x0000, 0x7C00, 0x7E00, 0x6300, 0x6300, 0x6300, 0x6300, 0x7E00, 0x7E00, 0x6300, 0x6180, 0x6180, 0x6380, 0x7F00, 0x7E00, 0x0000, 0x0000, 0x0000,  // B

0x0000, 0x1E00, 0x3F00, 0x3180, 0x6180, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6180, 0x3180, 0x3F00, 0x1E00, 0x0000, 0x0000, 0x0000,  // C

0x0000, 0x7C00, 0x7F00, 0x6300, 0x6380, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x6300, 0x6300, 0x7E00, 0x7C00, 0x0000, 0x0000, 0x0000,  // D

0x0000, 0x7F80, 0x7F80, 0x6000, 0x6000, 0x6000, 0x6000, 0x7F00, 0x7F00, 0x6000, 0x6000, 0x6000, 0x6000, 0x7F80, 0x7F80, 0x0000, 0x0000, 0x0000,  // E

0x0000, 0x7F80, 0x7F80, 0x6000, 0x6000, 0x6000, 0x6000, 0x7F00, 0x7F00, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x0000, 0x0000, 0x0000,  // F

0x0000, 0x1E00, 0x3F00, 0x3180, 0x6180, 0x6000, 0x6000, 0x6000, 0x6380, 0x6380, 0x6180, 0x6180, 0x3180, 0x3F80, 0x1E00, 0x0000, 0x0000, 0x0000,  // G

0x0000, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x7F80, 0x7F80, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x0000, 0x0000, 0x0000,  // H

0x0000, 0x3F00, 0x3F00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x0C00, 0x3F00, 0x3F00, 0x0000, 0x0000, 0x0000,  // I

0x0000, 0x0180, 0x0180, 0x0180, 0x0180, 0x0180, 0x0180, 0x0180, 0x0180, 0x0180, 0x6180, 0x6180, 0x7380, 0x3F00, 0x1E00, 0x0000, 0x0000, 0x0000,  // J

0x0000, 0x60C0, 0x6180, 0x6300, 0x6600, 0x6600, 0x6C00, 0x7800, 0x7C00, 0x6600, 0x6600, 0x6300, 0x6180, 0x6180, 0x60C0, 0x0000, 0x0000, 0x0000,  // K

0x0000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x7F80, 0x7F80, 0x0000, 0x0000, 0x0000,  // L

0x0000, 0x71C0, 0x71C0, 0x7BC0, 0x7AC0, 0x6AC0, 0x6AC0, 0x6EC0, 0x64C0, 0x60C0, 0x60C0, 0x60C0, 0x60C0, 0x60C0, 0x60C0, 0x0000, 0x0000, 0x0000,  // M

0x0000, 0x7180, 0x7180, 0x7980, 0x7980, 0x7980, 0x6D80, 0x6D80, 0x6D80, 0x6580, 0x6780, 0x6780, 0x6780, 0x6380, 0x6380, 0x0000, 0x0000, 0x0000,  // N

0x0000, 0x1E00, 0x3F00, 0x3300, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x3300, 0x3F00, 0x1E00, 0x0000, 0x0000, 0x0000,  // O

0x0000, 0x7E00, 0x7F00, 0x6380, 0x6180, 0x6180, 0x6180, 0x6380, 0x7F00, 0x7E00, 0x6000, 0x6000, 0x6000, 0x6000, 0x6000, 0x0000, 0x0000, 0x0000,  // P

0x0000, 0x1E00, 0x3F00, 0x3300, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x6180, 0x6580, 0x6780, 0x3300, 0x3F80, 0x1E40, 0x0000, 0x0000, 0x0000,  // Q

0x0000, 0x7E00, 0x7F00, 0x6380, 0x6180, 0x6180, 0x6380, 0x7F00, 0x7E00, 0x6600, 0x6300, 0x6300, 0x6180, 0x6180, 0x60C0, 0x0000, 0x0000, 0x0000,  // R

};

[Tesla DeLorean]

Well 32 is the ASCiI value for a SPACE, which is where the bitmap table starts​. Below 32 are unprintable control characters.

ASCII character 48 is the 0 symbol

[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 · Accepted solution]

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.