Can I use printf to print to terminal?

[JeCo_264681]

Starting with the Example program UART_Tx01 I successfully printed its output to a Teraterm window. I used an FTDI USB to TTL Serial Cable.

   

But I would like to print floating point numbers to the terminal using printf. The project build okay using:
 printf("Test printf function. float:%f \n",f);
where f is a float variable. But nothing prints on the terminal.
The LCD_Char_1_PrintInt8(count); function works fine but I want to format floating point output.

   

I am using the CY8KIT-050 and PSoC Creator 3.3

[Bob_Marlowe · Accepted solution]

Set "Use newlib nano Float Formatting" in project settings and increase heap size to at least 0x0200 bytes in .cydwr view, system tab.

       

Bob

[JeCo_264681]

Thank you, Bob. I tried that but still no fprint to the Teraterm terminal. I increased heap size to 0x0800 in cydwr System tab. For future readers of this search, Bob is saying go to Project tab > Build Settings > Linker > General > Use newlib Float Formatting = True.

   

The only display in Teraterm terminal is the LCD_Char_1_PrintInt8(count); that displays on the LCD of the development board.

   

Attached is the project. The only change I made to the Example is to add the fprint statement in a loop. Oh. I also added #include <stdio.h> and included Build Settings > Linker > General > Additional Libraries > m

   

I cannot find any reference to this problem is the search results. Any help is welcome.

[Bob_Marlowe]

Baud rate of your UART is non-standard, use during test phase 9600 baud.

   

Let the UART handle the interrupt, set Tx buffer to 80 and uncheck other interrupt sources

   

Check connection of port P0_1 with plugs on P5 serial tx line (2)

   

You have not provided the needed _write() function for GCC. How should C know that you want to have print going to your UART and not to another device

   

/* For GCC compiler revise _write() function for printf functionality */
int _write(int file, char *ptr, int len)
{
    int i;
    file = file;
    for (i = 0; i < len; i++)
    {
        PuTTY_PutByte(*ptr++);   // send to your device
    }
    return len;
}
//***********************************************************************************//

       

Bob

[JeCo_264681]

Bob, Your comment is quite helpful regarding "how should C know" where to direct print. I will experiment with this and close when I have a working model. Thank you.

[JeCo_264681]

Thanks again, Bob. I fixed it. I used sprintf()  instead of printf() to print floating point to a string. Then I  redirected output to UART instead of the LCD. I should have thought of that! I also added #include <string.h> but don't know if that's necessary So I have:

   

   #define CR (0x0Du) // carriage return character
   #define LF (0x0Au) // define line feed character
   float f;
   ....
    char num[] = "1.3456789012345"; // initialize the string to receive floating point data
   char *p;
        sprintf(num,"%-f", f);     // convert floating to string left justified
        p = num;  // pointer to start of num string
        /* The while loop will execute until a null end-of-string character is found */
        while (*p) UART_1_WriteTxData(*p++); /* Sending the data */
        UART_1_WriteTxData(CR); // write carriage return
        UART_1_WriteTxData(LF); // write line feed

   

How do we mark an answer as "Verified?"

[Bob_Marlowe]

How do we mark an answer as "Verified?" I don't know, but I am quite content as long as you don't flag it as "offensive" 😉

       

Bob

[JaOs_1501976]

Hi Bob, Thanks for your comment on increasing the heap size, it helped a lot. Jacek

[Anonymous]

Yeah usually strange behavior is indication to suspect on heap..

   

But for terminal window try http://docklight.de/  at least it is my favorite 🙂