At 09:58 AM 7/16/98 GMT+0200, you wrote:
>Hi,
>
>> Hi everyone,
>>         I'm trying to find some code for a frequency genetator using a PIC.
>> 0Hz to 10khz    0.5Hz or 1Hz increments.
>> I have been experiementing with PIC16C84, dividing a known frequency
>> from the TRM0 Interupt, but dividing freqencies will not give me the
>> freqency increments I need.
>> eg 1MHz/100 = 10kHz
>>    1MHz/101 = 9900.9Hz
>>
>>    1MHz/1,000,000 = 1Hz
>>    1MHz/1,000,001 =0.9999999
>>
>> Any help will be greatly appretiated
>>
>I designed a 1-10KHz frequency generator with a 1Hz resolution about a
>year ago.  I used a numerically controlled oscillator (NCO) IC from
>Harris (HSP45102) with a PIC.  You simply download the divisor to the IC
>via its SPI interface.  It actually outputs a 12 bit sine wave but I only
>used the most significant bit to get a square wave.
>
>I don't think that a PIC alone would be sufficient.  You could also use a
>PLL frequency synthesizer.  The problem is that 1Hz-10KHz spans 4 decades
>which would make the oscillator design tricky.
>
Motorola MC145162 is also a good choise for frequency division, you may
use this IC to output to two different frequencies. More DDS chip from Analog
Device may be used, or use PIC to do the DDS, I've read a article from
Motorola web talking about DDS using a MC68HC05 I believe.