Amberdrew Ltd wrote:
>
> Peter Homann wrote:
> >
> > Hi,
> >
> > I need to measure a continuous frequency between 0 - 250 cycles/MINUTE,
> > and transmit it via RS-232 at 2400 baud in a message containing 6 bytes
> > once 5 seconds.
> >
> > The PIC I plan to use is the low power 84 variant, running at 32 KHz,
> > if possible.
> >
> > The two separate requirements are easy to implement on their own, it's
> > getting the PIC to implement them concurrently that I'm having trouble
> > with. I need to continue measuring the input frequency even while I am
> > transmitting the output message.
> >
> > I'd appreciate it if anybody who has solved this type of problem, can
> > give me a few pointers as this type of task, measure an input and
> > transmit it must be quite common.
> >
> > With the PIC running at 32KHz, it is only operating at 8K instructions
> > per second. Transmitting at 2400 baud, there is time for only 7
> > instructions per bit.
> >
> > I been tossing ideas around for a number of months now with no real
> > solution comming forward. I could use 2 Pics, one to do the counting,
> > the other to do the transmitting, but then I might as well use a
> > faster crystal.
> >
> > Are there other alternatives? I may be blinkered down a set path.
> >
> > Any input would be great. Code fragments would be fantastic.
> >
> > Thanks guys,
> >
> > Peter.
> > --
> > _______________________________________________________________________
> > Peter Homann   email: peterh@adacel.com.au       Work : +61 3 9596-2991
> > Adacel Pty Ltd                                   Fax  : +61 3 9596-2960
> > 250 Bay St, Brighton 3186, VIC, AUSTRALIA      Mobile :     014 025-925
>
> Hi, I have been working on a system that counts pulses and pulse width
> using the 84 .I use both the T0 clock and INT on portB0 to generate
> ints.
> If you set the ints up so that an int is generated on the rising edge of
> portb0 and increment a counter every time an int is generated you can
> count pulses. now if you also set the clock to generate an int at a set
> duty cycle you can count the number of pulses on the portb0 pin within a
> set time. all of this can be done in the background and due to the
> nature of the ints it is also VERY presise.
>
> I hope this is of some use
>
> Peter........


I think the problem is that the output of serial data will be
corrupted by the interrupts.

Peter.
--
_______________________________________________________________________
Peter Homann   email: peterh@adacel.com.au       Work : +61 3 9596-2991
Adacel Pty Ltd                                   Fax  : +61 3 9596-2960
250 Bay St, Brighton 3186, VIC, AUSTRALIA      Mobile :     014 025-925