Hi Praveen,
Have you looked in the docs, in Building Embedded Systems?
http://www.qnx.com/developers/docs/660/topic/com.qnx.doc.neutrino.building/
topic/bsp_Flash_filesystem.html
N

On 2014-09-09 3:05 , "Praveen Kumar" <community-noreply@qnx.com> wrote:

>Hi All,
>I am trying to create a RAW partitions on SDCard and then do a read write
>to it.Can anybody give info on this creation and read write method.
>
>thanks,
>with regards,
>praveen kumar
>
>
>
>_______________________________________________
>
>OSTech
>http://community.qnx.com/sf/go/post111677
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Use fdisk to create a partition OF ANY TYPE (say 77).  Do not format the partition!
# fdisk /dev/hd2   ...and use menu

Do this to read/accept new partition table.
# mount -e /dev/hd2

From your program you can..
fd = open( "/dev/hd2t77", O_RDWR );
len = read( fd, buf, 512 )l;

or
# hd /dev/hd2t77

or to read entire partition
# dd if=/dev/hd2t77 of=/dev/null

Hi,
Thanks for the immediate reply.I used the fdisk method to create a RAW partition on SD Card giving the below command 
fdisk /dev/hd0 add -t 3 -p 10
Then i tried to write to the partition opening the partition in a c program with the following code
int fdd = open("/dev/hd0t3",O_RDWR);
then i am trying to write a structure data to the partition in the following manner

write(fdd,(const void*)&wrbuff,sizeof(wrbuff));//where the wrbuff has the members char,float,int

when i try to read back from the partition 
read(fdd,(void*)&rdbuff,sizeof(rdbuff));//another instance of the same buffer 
the data is not getting read back correctly am i doing any mistake in my code please advice.
Thanks with regards
Praveen Kumar V S

Hi,
This is my minimal code

#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mount.h>
struct databuffer
{
    char chardata;
    float floatdata;
    int intdata;
};

int main(int argc, char *argv[]) {

struct databuffer datbuf,rddatbuf;
int fdd=0,readcount=0;
fdd = open("/dev/hd0t3",O_RDWR);
    if(fdd < 0)
    {
    	printf("fd open error");
    }
    datbuf.chardata='a';
    datbuf.floatdata=1.152;
    datbuf.intdata=20;

    write(fdd,(const void*)&datbuf,sizeof(datbuf));


    read(fdd,(void*)&rddatbuf,sizeof(rddatbuf));
    printf("%c___,%f___,%d___\n",rddatbuf.chardata,rddatbuf.floatdata,rddatbuf.intdata);
    close(fdd);
return 0; 
}

As said in your mail i have not used the lseek i need to add it before the read command.I have another problem i am 
trying to open a new file in the file system and write to it but my program is crashing.
My sample code
The code is crashing on the fopen call itself is there anything to be done before fopen
int mountret=mount("/dev/hd0t1","/usr",_MOUNT_REMOUNT,"dos",'\0',-1);

    fd=fopen("/usr/test/data.txt",'a');
    if(fd==NULL)
    {
       printf("fopen error");
    }
    datbuf.chardata='a';
        datbuf.floatdata=1.152;
        datbuf.intdata=20;

        fwrite((const void*)&datbuf,sizeof(datbuf),1,fd);
        fclose(fd); 


Thanks for your response it is very helpful.

With Regards,
Praveen Kumar