On 5/1/07, Michael Rigby-Jones wrote: > > > >-----Original Message----- > >From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] > >On Behalf Of PAUL James > >Sent: 30 April 2007 20:15 > >To: Microcontroller discussion list - Public. > >Subject: RE: [PIC] [EE] Signal Generator > > > > > > > > > > > >Or go to Analog Devices and get a DDS (Direct Digital > >Synthesis) generator chip. Add a high frequency master > >oscillator, and a microcontroller with keypad and LCD, And get > >any frequency between DC and master oscillator/2 in sub hertz > >increments. > > > >I've done this and it works great. > > > Unfortunately the output at Fosc/2 is a square wave, you really need to have either a tracking filter or limit output frequency to a small fraction of the master clock. That makes the spurious free dinamic range (SFDR) with a perfect second order low pass filter can be around -55...-60dB while without filter around -40dB. It's that enough ? -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist