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vinniewryan
Joined: 29 Jul 2009
Posts: 154
Location: at work
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| adding values to a text string |
 Posted: Wed Aug 11, 2010 10:06 pm |
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I have a basic question,
I'm trying to read the inputs of 3 ADC pins on my PIC16F684, and save them all to one text string that will then be sent to an LCD using RS232 communication. My question is, it there a way to add values to a text string?
For example, this is what I want to do:
| Code: |
set_adc_channel(1);
VAR=read_adc(); //let's pretend ADC reads 103
//ADD VAR to text string, followed by a comma. Now text string should read "103,"
set_adc_channel(2);
VAR=read_adc(); //let's pretend ADC reads 244
//ADD VAR to text string, followed by a comma. Now text string should read "103,244,"
set_adc_channel(3);
VAR=read_adc(); //let's pretend ADC reads 77
//ADD VAR to text string, followed by a comma. Now text string should read "103,244,77,"
putc("text string"); //send text string to LCD via RS232
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So the LCD should receive "103,244,77,". Is this possible? I want to use my PIC as a data logger, but I don't want to create an identifier for every value being recorded. I would prefer to save all recorded values in a CHAR array that can be sent to the LCD in one 'putc' command.
The code, when finished, will record data from the ADC inputs 5 times per second for 5 seconds, so it would take 25 identifiers to accomplish this, and that's just a sloppy way to do this.
Thanks!
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Vinnie Ryan |
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Audi80
Joined: 07 Sep 2007
Posts: 41
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| Posted: Thu Aug 12, 2010 6:46 am |
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Hi there, the simplest thing to do is use strcat
Ex:
| Code: |
char completeString[100];
void addValue(char * newAdcValue){
strcat(completeString,newAdcValue);
printf("Whole new String: %s\r\n",completeString);
}
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Test it and see if it works, best regards... |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Thu Aug 12, 2010 6:55 am |
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I don't understand why you can't write each part to the LCD separately.
Instead of strcat you could use printf: | Code: | set_adc_channel(1);
var1=read_adc(); //let's pretend ADC reads 103
set_adc_channel(2);
var2=read_adc(); //let's pretend ADC reads 244
set_adc_channel(3);
var3=read_adc(); //let's pretend ADC reads 77
printf("%d,%d,%d,", var1, var2, var3); //send text string to LCD via RS232 |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19552
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| Posted: Thu Aug 12, 2010 7:55 am |
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A series of comments:
1) The ability to send a multi-character string with putc, _only_ applies to constant strings. The string will need to be printed out a character at a time, or sent with puts/printf.
2) As another poster has said, why not just printf the values. If you are worried about timing, consider using buffered interrupt driven transmit (ex_stisr.c), and print to this.
3) if you must have a string, you can generate it, using sprintf, in one go, or if you 'must' do it a section at a time, generate it in parts, then assemble using strcat.
Best Wishes |
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vinniewryan
Joined: 29 Jul 2009
Posts: 154
Location: at work
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| Posted: Fri Aug 13, 2010 2:26 pm |
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compiler version 4.0.3
After trying all mentioned methods, I decided to just pay $0.60 for a memory chip. I didn't realize they're so cheap! So now that problem is solved.
Which brings me to my new problem, which I'm currently researching. I can't seem to send an int16 via printf or puts. This is the context:
| Code: |
//un-important setup stuff here
#use RS232(BAUD=19200,INVERT,LONG_DATA,FORCE_SW,XMIT=pin_a0)
long X;
X=Read_ADC();
puts("%d", X);
printf("%d", X);
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when I set X as a LONG (16 bit), the compiler gives me an error "Print format type is invalid". When I set X as 'char', the compiler returns no errors, but only outputs 8 bits.
I need 16 bit values to be sent to my LCD but the compiler won't let me do this with my current methods.
Any ideas?
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Vinnie Ryan |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Aug 13, 2010 2:32 pm |
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| Quote: | | I need 16 bit values to be sent to my LCD but the compiler won't let me do this. |
It will, and it's in explained in the CCS manual.
http://www.ccsinfo.com/downloads/ccs_c_manual.pdf
Look in the printf section of the manual. There is a table of format
values to use, to display any data type (including 16-bit). In the June
2010 manual, this is on page 207 (page 219 in the acrobat reader). |
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vinniewryan
Joined: 29 Jul 2009
Posts: 154
Location: at work
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| Posted: Fri Aug 13, 2010 2:43 pm |
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Thank you PCM, you just solved my problem! I overlooked the table, thanks for the info!
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Vinnie Ryan |
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