Hexnr. through serial COM port

**overspray** · 07-18-2004

Hi,
I´d like to send hexnumbers through the serial interface of a PC to a µ processor.
It works with a terminal, when I hit a key, for example 'a', 0100001 is stored in the µp register.
This I`d like to accomplish with the following C++ routine:

while(i<rows &&fgets(buff, sizeof(buff), HexCode) != NULL
{
for ( j=0; j<=1; j++ )
{
if (sscanf(&buff[0],"%c%c",&x[i][j])==1)
i++ ;

( Im intending to grab the first two chars of a textfile, resembling the byte in Hex format, like:
FD
9A
DF.......

The send routine through Com1 looks like this:

WriteFile(hCom, &x[][], sizeof (x[][] ), &dwWritten, NULL);

The PC crashes upon compilation, though.

Im I doing the right thing to achiev what I want?
I`d appreciate any help.

**Salem** · 07-18-2004

So are you trying to send say FD as one byte - 0xFD or as two bytes of a string "FD"

And what's with all the x[][] ?

PS
Don't forget the code tags

**overspray** · 07-18-2004

I`m not shure.I think it should be sent as one byte, sunce that`s what the µp processes at he other end.
Is that what happens when I hit a key of the keyboard?

the [][] contain the indexes of the for loops.

Do hou have any idea how to send this data as one byte?

**Salem** · 07-18-2004

I guess something like this

Code:

    char buff[] = "FCDA\n"; // example buffer from fgets
    int x;
    unsigned char c;
    sscanf(buff,"%02x",&x); // take only the first 2 chars
    printf("%x\n",x);
    c=x;                    // make it a single char
    WriteFile(hCom, &c, 1, &dwWritten, NULL);

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