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runtime
Joined: 15 Sep 2003
Posts: 36
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| fprintf and disable_interrupts(int_ext), please help... |
 Posted: Thu Jul 22, 2004 8:56 am |
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Hello all,
#use rs232(baud=4800,xmit=MOut,rcv=MIn,stream=MODEM)
In several parts of my program I have the following code, with different strings sent to the MODEM:
disable_interrupts(int_ext);
fprintf(MODEM,"AT#CONNECTIONSTART\r");
enable_interrupts(int_ext);
I have 3 questions, please help me out:
1) If I remove the disable/enable interrupts instructions, it does not work (I can not talk or receive the modem), why is that?
2) how can i convert the above code into a function in which I pass the string I want to send as a parameter?
3) is it ok to use fprintf?, I've read it's best to use fputc in a loop but I don't know how...I'm using STREAMS, have a modem, GPS and PC...
Thank you in advance
Peter |
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Ttlmah
Guest
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| Re: fprintf and disable_interrupts(int_ext), please help... |
| Posted: Thu Jul 22, 2004 9:14 am |
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| runtime wrote: | Hello all,
#use rs232(baud=4800,xmit=MOut,rcv=MIn,stream=MODEM)
In several parts of my program I have the following code, with different strings sent to the MODEM:
disable_interrupts(int_ext);
fprintf(MODEM,"AT#CONNECTIONSTART\r");
enable_interrupts(int_ext);
I have 3 questions, please help me out:
1) If I remove the disable/enable interrupts instructions, it does not work (I can not talk or receive the modem), why is that?
2) how can i convert the above code into a function in which I pass the string I want to send as a parameter?
3) is it ok to use fprintf?, I've read it's best to use fputc in a loop but I don't know how...I'm using STREAMS, have a modem, GPS and PC...
Thank you in advance
Peter |
You don't tell us whether there is a hardware, or software UART, on this stream?.
I'd guess it is a software UART. If so, then this explains the interrupt problem. The problem here is that the sgftware UART is totally dependant on accurate software timings. Unfortunately, and interrupt will itself introduce a time error, and the comms will stop working.
The alternative that I'd consider is something like this:
| Code: |
void intoffputc(int8 val) {
disable_interrupts(INT_EXT);
fputc(val,INT_EXT);
enable_interrupts(INT_EXT);
}
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Now this will take a single character, disable the interrupts, send this character, and then re-enable the interrupts. For your example string, you can then use:
intoffputc("AT#CONNECTIONSTART\r");
This uses the CCS 'shortcut', which for a constant string, will call a function expecting to receive an integer, character at a time, for each character in the string. The advantage, is that the interrupts will only be disabled for one character time, instead of for the length of the whole string.
The same routine can be used if you need formatted output, with printf, using syntax like:
printf(intoffputc,"sending a number %d\n",num);
Best Wishes |
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runtime
Joined: 15 Sep 2003
Posts: 36
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| Posted: Thu Jul 22, 2004 9:28 am |
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Hello Ttlmah,
Thank you for your response, in your code:
fputc(val,INT_EXT); wouldn't that be fputc(val, MODEM)?
Thank you |
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Ttelmah
Guest
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| Posted: Thu Jul 22, 2004 10:17 am |
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| runtime wrote: | Hello Ttlmah,
Thank you for your response, in your code:
fputc(val,INT_EXT); wouldn't that be fputc(val, MODEM)?
Thank you |
Yes.
As you can tell, the code was 'off the cuff', and I just slipped on the name of the tream (in a rather silly way). I was using 'INT_EXT', in the line before and after...
For my 'next trick', I'll try 'disable_interrupts(MODEM)'...
:-)
Best Wishes |
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