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Guest
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| #ZERO_RAM side effects? |
 Posted: Thu Dec 03, 2009 2:44 pm |
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Hi:
I'm using the #ZERO_RAM directive, and I am wondering if there are any side effects. In the code below, if I use it, my serial ISR does not work. Without the #ZERO-RAM directive, it does
-Jeff
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| Code: | #include <18F67J50.h>
#fuses HS,NOWDT,NOPROTECT
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
/** local definitions **/
char buffer[81]; // Where the serial data is stuffed
char buffer_pos=0;
/** default settings **/
//#ZERO_RAM commented out it works
void main(void)
{
enable_interrupts(INT_RDA);
enable_interrupts(GLOBAL);
while (TRUE)
{
// Service things here
}
}
#int_RDA
void get_buffer(void) // get the message from the GPS module
{
output_toggle(PIN_E2);
if(kbhit()) // check if uart filled
{
buffer[buffer_pos]=getc(); // get info
buffer_pos++;
if(buffer[buffer_pos-1]==10) // Linefeed as end of record
{
// if(log_flag) log_buffer(buffer_pos-1);
//!! Put in a flag to see if read_buffer updated anything
//SentenceID = read_buffer(); // Sentence ID tells us what sentence was read
buffer_pos=0;
}
}
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Dec 03, 2009 2:59 pm |
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What's your compiler version ? CCS has this note on their versions page:
| Quote: |
4.014 A problem using ZERO_RAM and ICD=TRUE together on some PIC18 parts is fixed |
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Guest
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| Posted: Thu Dec 03, 2009 10:03 pm |
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| 4.101 |
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Ttelmah
Guest
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| Posted: Fri Dec 04, 2009 3:26 am |
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Add 'ERRORS' to your RS232 directive.
One possibility, is that ZERO_RAM, takes significant time during bootup. Without 'ERRORS', the UART will hang, if more than a couple of characters are received, and not handled. If you were running at a much higher baud rate, I'd say this was 'likely', but at 9600bps, each character takes a mSec, and though in computer terms clearing all the RAM memory takes a lot of cycles, I can't see it taking even remotely near this sort of time....
However the ERRORS directive, ought to _always_ be present when using the hardware RS232, unless you are providing similar code yourself, so it is worth trying.
Best Wishes |
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