Hardware uart and rtcc ?

[ljb]

I have a time stamp being updated using the RTCC interrupting on overflow which works fine when left alone.
When data is being sent over the h/w uart the time freezes (noticable when sending large amounts of data).
A loop is executed reading data from ext ram over an i2c bus and sent using printf, until all data are sent.
It looks like the RTCC is being reset each time round the loop, but I have selected NOWDT. Does the h/w uart clear the RTCC for some reason?
Is this correct? and is there a way around it?
I am using a 16f876 @ 16mhz.
Many thanks
Les

[Haplo]

Even with NOWDT selected, a CLRWDT will probably still clear the watchdog prescaler. Do you have the word 'restart_wdt' in your #use rs232 statement by any chance?

[ljb]

There are no reference to the wdt, either setting up or to clear.
I was wondering if the h/w uart has some direct connection to rtcc which is implemented when used, how else would it know to clear the wdt if :-
printf("some text");
or
ch=getc();
are used ?
cheers
Les

[Ttelmah]

[treitmey]

I'm no expert in this area,... perhaps someone else can confirm this...

but if your sending data real real fast, would the #int_TBE for the serial send could be interupting so fast as to not let the timer funtion interupt.

??

maybe a ((fast interupt))) [[scary new area for me : ) ]] that could get in an interupt even as #int_TBE interupt was working.

That is if you are using a TX buffer and interupt driven Tx.

[Ttelmah]

[Ttelmah]

Change this to say if the priority of the TBE interrupt is _above_ that of the timer interrupt...
:-)

Best Wishes

[Mark]

Actually a problem could occur no matter what the data rate if the programmer does not disable the TBE int when all the data has been transmitted since the flag bit is controlled by hardware.