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GPS with PIC microcontroller

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ExperimenterUK

Tue Nov 25 2008, 08:19AM

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Actually I think the standard NMEA baud rate is 4800

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monika

Tue Nov 25 2008, 11:40PM

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My receiver is working fine with PC com port and it is giving NMEA format in the hyperterminal. There is no such kind of problem.

Firstly I want to read my data (say my data is: hello) in an array and then transmit it.
That's why i am using 9600 baud rate.

Ajay

Wed Nov 26 2008, 11:39AM

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monika is your hardware able to send data to terminal?

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sashijoseph

Wed Nov 26 2008, 06:56PM

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In your putch and getch functions,are the TXIF and RCIF flags cleared by hardware?
Don't you have to clear them explicitly? What does the datasheet say?

And have you tried Ajay's and ExpUK's suggestions...just send a string and see if you can receive it in hyperterm.

If it works,then try getting your baudrate down to 4800.

Let there be music........

monika

Wed Nov 26 2008, 09:19PM

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In my code, TXIF and RCIF flags are cleared implicitly. I am using PIC 16F690. There is no need to clear the flags in it.

I am able to send a character at a time using my hardware and getting the output in hyperterminal with baudrates 9600 and 4800. The problem occurs when I work with string.

ExperimenterUK

Fri Nov 28 2008, 12:17PM

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Did you try the code I suggested in an earlier post ?

>I would create a test program, something like this just to see what I get.
>char testMsg[]="Test***";
>int n=0;
etc

It would be safer to introduce a small delay before sending the string
to allow the internal oscillator to stabilise.
Better still use an external crystal.

Learning all the time

monika

Thu Dec 04 2008, 10:35PM

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yes I have tried your code and it is working fine. I have introduced a delay before sending the string as:

do
{
read=get_ch();
msg_rec[i]=read;
i++;
delay_ms();
}while(i<20);

msg_rec[i]='\0';

while(msg_rec[j]!='\0')
{
putch(msg_rec[j]);
j++;
}

I read a character and then store it in array, after that I have given a delay to stabilize the internal oscillator . only then i read another character.

but still there is no output in the hyperterminal.

ExperimenterUK

Thu Dec 04 2008, 11:45PM

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monika wrote ...

yes I have tried your code and it is working fine.

Do you mean you reset the PIC and it prints out the test message in hyperterminal ?

The delay I mentioned was between reset and starting to print the test string,
a few milliseconds, just in case the internal oscillator took a while to stabilise.

Can you post a diagram of how these items are connected ?

[ Edited Thu Dec 04 2008, 11:50PM ]

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