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........