Semihosting problem with IMXRT1050-EVKB on MCUXpresso IDE

[tobias_chalupka]

Hello there,

I cannot seem to read from a file when using semihosting in the MCUXpresso IDE v10.2.1 with the IMXRT1050-EVKB.

I followed the step-by-step guide and successfully ran the "Hello world" example on the board. The board is connected via USB to my Windows 7 PC.

I've set the library/header type to "Newlib (semihost)" via the the quick settings. And added some fopen(), fprintf() and fscanf() routines to the example (the whole project including the changed hello_world.c is attached).

The thing the main program now should do is to open a file, write "Hello World!" to it, read the contents of the file again to strings and print it out on stdout. But, I get only garbage when reading from the file. When I examined the file, I found that the writing had worked correctly.

The program's output is:

[[MCUXpresso Semihosting Telnet console for 'evkbimxrt1050_hello_world_file LinkServer Debug' started on port 56900 @ 127.0.0.1]

+b  ðÿÿÿÿÿÿÿÿ  .


[Closed Telnet Session]

The string is supposed to be the string "Hello World!", as read from the file. Is this a known problem with the semihosting? Is there an update or at least a workaround? Reading from files is essential for our demo applications.

Note: With the redlib (semihost) library, even file opening does not work at all.

Unfortunately, I cannot attach the project fie because the site won't let me ("An unexpected error has occurred. Please make sure that your session did not expire while viewing this page."). So I added only the relevant content of hello_world.c at the end of this post.

Thanks for any help!

/*!
 * @brief Main function
 */
int main(void)
{
    char ch;
    FILE *myfile;
    char mystrings[2][10];

    /* Init board hardware. */
    BOARD_ConfigMPU();
    BOARD_InitPins();
    BOARD_BootClockRUN();
    BOARD_InitDebugConsole();

    /* Write to file */
    myfile = fopen("tmp.txt", "w");
    if (myfile == NULL) {
        fprintf(stderr, "Could not open file for writing\n");
        return 1;
    }
    fprintf(myfile, "hello world.\n");
    fclose (myfile);

    /* Read from file */
    myfile = fopen("tmp.txt", "r");
    if (myfile == NULL) {
        fprintf(stderr, "Could not open file for reading\n");
        return 1;
    }
    fscanf(myfile, "%s %s", mystrings[0], mystrings[1]);
    fclose (myfile);

    /* Print file's contents */
    printf("%s %s.\n\n", mystrings[0], mystrings[1]);

    while (1)
    {
        ch = GETCHAR();
        PUTCHAR(ch);
    }
}

[Takashi_Kashiwagi]

Hi Chalupka

Since SWO is not connected by IMXRT 1050 - EVKB by default, semihosting by SWO or SWO trace can not be used as it is.

As an alternative interface, Windows recognizes the COM port (LPUART 1).

If you want to Change the Standard IO to LPUART, please see "utilities\io\swo\fsl_io.c" in FSL SDK.

Best Regards,

T.Kashiwagi