Problems with data receive in TCP/IP

[RavensFan]

You can certainly do that.  But I'm sure you can send the data as bytes and not just as ASCII strings.

If you attached your C code, someone may help.  (though this is a LabVIEW forum and not a C forum.)

In Basic, if you want to print a non-printable character, you'd print out something like chr$(10) which is the new line/linefeed character.  I'm sure C has some equivalent function.

[iman_h]

I am searching for the solution in ARM related forums. The ethernet library which I used, is utilizing a high level function for data sending. There must be some low-level functions to send bytes instead of string. I can not shift or replace ASCII characters, becuase I need the complete 0 to 255 values to send numeric data.

Thanks.

[billko]

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@iman_h wrote:

I am searching for the solution in ARM related forums. The ethernet library which I used, is utilizing a high level function for data sending. There must be some low-level functions to send bytes instead of string. I can not shift or replace ASCII characters, becuase I need the complete 0 to 255 values to send numeric data.

Thanks.

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It's hard to believe the library would require you to send ASCII.  That would make it almost totally useless.  How would you use this library to download a zip file, for instance?  Remember also that you would have to have a decoder on the other side to decode the ASCII back into a binary string.  In other words, a version of this library would have to exist on every single thing it is communicating with.

I think you are unnecessarily hung up on the fact that it is sending strings.  Sending a string is just a way to send bytes of data.  Remember, a string can contain non-printable characters, too.

[iman_h]

Let me attach some piece of code:

Spoiler

// buffer is an array of uint8_t
// In library prototype, the data is sent like this:
sprintf(str,"%s\n\r\n\r",buffer);
plen=fill_tcp_data_p(buf,0,(const unsigned char *)(str));

make_tcp_ack_from_any(buf); // send ack for http get
make_tcp_ack_with_data(buf,plen); // send data

These are the definition of functions:

Spoiler

unsigned int fill_tcp_data_p(unsigned char *buf,unsigned int pos, const unsigned char *progmem_s)
{

char c;

// fill in tcp data at position pos
//
// with no options the data starts after the checksum + 2 more bytes (urgent ptr)
while ((c = pgm_read_byte(progmem_s++)))
{
buf[TCP_CHECKSUM_L_P+3+pos]=c;
pos++;
}
return(pos);
}

As I understood, when we fill buffer like this:

buffer[5]={48,64,112,0,65};

It is converted into a string like this:

str=0 @ p \0 A

I think the \0 between the array of characters, make the function terminate the string and send: 0 @ p. (Three bytes instead of 5 bytes)