File IO

Dan S17

I want to read data from a file at the start up of my Hercules ucontroller code. Are there any hurdles to doing this that I should know about before I begin or is it file IO as usual?

Thank you,

Daniel

over 10 years ago

0 QJ Wang over 10 years ago

TI__Guru**** 197306 points

Hi Dan,

You can use fread/fopen as usual.

The RTS has a very low limit on the number of files you can open simultaneously. Always check the return value of fopen() to make sure the file was opened successfully. If the file you are opening is a binary file, be sure to use 'rb', otherwise the file contains data with a "0" byte, the RTS will mistake that for the end of file.

Regards,
QJ

0 Dan S17 over 10 years ago in reply to QJ Wang

Expert 1510 points

Hmm. File IO is not working for me. I can't even get a message to print to the console (I assume that is where it will print.). If use this code to error-check fopen() I get nothing printed to the console at all:

data_file = fopen("C:\\Users\\BIC\\workspace_v6_0\\Blinky\\data.txt","r");
if(data_file == NULL){
printf("Can't open data.txt");
} else {
printf("Opened data.txt ");
}

Any ideas why?

0 QJ Wang over 10 years ago in reply to Dan S17

TI__Guru**** 197306 points

Hi Dan,

For using printf in CCS, please refer to the thread below:

http://e2e.ti.com/support/microcontrollers/hercules/f/312/p/323378/1126338#1126338

Regards,

0 Dan S17 over 10 years ago in reply to QJ Wang

Expert 1510 points

HI QJ

I put the line:

/* USER CODE BEGIN (4) */
.sysmem : {} > RAM
/* USER CODE END */

in sys_lnk.cmd but my simple printf code is still not working.

PS: I just noticed that the line in question was already in sys_lnk.cmd. Still don't know how to get a simple read of an ascii file done before the code is flashed to the ucon. Please help.

Daniel

0 Dan S17 over 10 years ago in reply to Dan S17

Expert 1510 points

Hmm. If I put a printf("Hello world) just before my fopen code (see previous post) then the "hello world" is printed to the console. But neither of the other two printf statements are printed to the console.

0 Dan S17 over 10 years ago in reply to Dan S17

Expert 1510 points

I have also tried flushing the stdout buffer (fflush(stdout)) but nothing works. Why can't I see the output of printf consistently?

0 Dan S17 over 10 years ago in reply to Dan S17

Expert 1510 points

Problem solved. Windows does not like file extensions. I dropped the .txt from the file name in fopen (and the file itself) and all worked fine.

I hate windows.

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File IO