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1953cub
Joined: 28 Jan 2014
Posts: 7
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| arrays, strings, rs232 with integers above 128 and 0 (solved |
 Posted: Sat Dec 26, 2015 9:14 am |
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compiler ver 5.051
PIC 18F45K22
Hello,
I apologize for the subject right off as I''m not sure how to best describe what I'm trying to figure out. But, here it goes.
I'm trying to wrap my head around sending and receiving integers above 128 decimal and also a zero via the rs232 port. And then searching a received string.
After reading the manual and on this site and going over example code I have a program that sends ASCII codes via the rs232 port and then receives a response and parses the response looking a sequence. All works great.
To send I use
| Code: |
fprintf(DEVICE,"TURNON"); // TURNON is the ascii code the device wants
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Now I need to do the same except this device uses integers above 128 and also 0 decimal in the form of a packet.
The new device wants this 0xa9,0x01,0x30,0x01,0x01,0x01,0x31,0x9a to turn on
So I created the following:
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int TURNON[8] = {0xa9,0x01,0x30,0x01,0x01,0x01,0x31,0x9a};
fprintf(DEVICE,TURNON);
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this works until I needed the send the turn off code which is
0xa9,0x01,0x30,0x00,0x00,0x00,0x31,0x9a
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int TURNOFF[8] = {0xa9,0x01,0x30,0x00,0x00,0x00,0x31,0x9a};
fprintf(DEVICE,TURNOFF);
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this only sends a9 01 30 then stops I'm guessing because 0x00 is a null and terminates the array input ? or ?
I also need to read a similar sequence in and parse it. I have been receiving the data on interrupt and creating an array, I copy the array to a string then search looking for a subset in it using the strstr function.
and since the incoming packet? has various 0x00 integers which are also nulls
Can anyone help me understand how to send and receive 0x00 as part of a "packet" via the serial port and also how to receive it and parse it ? I assume I cannot use strstr to do this since I'm not searching for an ascii character.
Happy to post my receive and parsing code if that would be helpful. but didn't want to confuse things, that might be obvious with a better understanding on my part
Thanks
Tim
Last edited by 1953cub on Mon Dec 28, 2015 4:17 pm; edited 2 times in total |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Sat Dec 26, 2015 9:37 am |
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You need to study fundamental C syntax.
In the first code example,
All you are actually doing is outputting the
QUOTED TEXT string .
your slave device is actually seeing the following ( if sent back to back).
TURNONTURNOFF
NOT the content of the named arrays.
in the second , the \0 chars are a problem as you see.
try this instead
| Code: | void do_on(void)
int i=0;
while (i<8){ putc(device,turnon[i++]);}
}
void do_off(void)
int i=0;
while (i<8){ putc(device,turnoff[i++]);}
}
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Last edited by asmboy on Sat Dec 26, 2015 9:46 am; edited 2 times in total |
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1953cub
Joined: 28 Jan 2014
Posts: 7
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| Posted: Sat Dec 26, 2015 9:45 am |
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Sorry, I had mistakenly typed the quotes in. I have the serial going to a PC for testing using "realterm" and set the display to hex with spaces. this is what I get when do the turn off send.
A9 01 30 |
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gpsmikey
Joined: 16 Nov 2010
Posts: 588
Location: Kirkland, WA
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| Posted: Sat Dec 26, 2015 9:56 am |
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Not sure if this is part of the problem you are seeing, but I have been bitten by it before - even if you do manage to send \0 as part of the character sequence, windows may be "helping" you by treating it as a special character. I have run into that before where it sees a CR or Newline (I forget exactly) and it appended the other part of the CR/LF to the character as it went by. Even Microsoft got bitten by that one in the past - back in the DOS days, if you created backup floppies on your system it worked great until the disk number was "0a" at which point it appended a "0D" to the character sequence which completely screwed up the backup sequence. They had to fix that one quickly  The \0 is definitely suspect since it is a string terminator (and you and windows may not agree on exactly what it should be doing with it when it sees it )
mikey
_________________
mikey
-- you can't have too many gadgets or too much disk space !
old engineering saying: 1+1 = 3 for sufficiently large values of 1 or small values of 3 |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Sat Dec 26, 2015 10:07 am |
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http://sourceforge.net/projects/realterm/
Realterm is KNOWN by this fellow to NOT have the behavior GPSMIKEY refers to, and of course your target device should not - as it is a device, not a computer at all, right ? |
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1953cub
Joined: 28 Jan 2014
Posts: 7
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| Posted: Sat Dec 26, 2015 5:37 pm |
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Thanks, asmboy I made a slight change to fputc to use the DEVICE stream and that part is now working. So getting fprint out and sending the array one byte at a time to fputc works !!
| Code: |
void do_on(void)
{int i=0;
while (i<8){ fputc(turnon[i++],device);}
}
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Thanks gpsmikey realterm was working correctly, setting the "display as" to Hex[space] allowed me to see the output correctly for testing. The real device is a control for a scientific instrument as asmboy mentions. But I will keep the windows issue in mind. |
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