On 25/06/2012 1:45 PM, Sergey Dryga wrote: > David Duffy (AVD audiovisualdevices.com.au> writes: > >> I'd like to make a programmable (serial control) oscillator as part of a >> test rig. >> >> All I need is square wave output (adjustable symmetry would be nice but >> not essential) and a frequency range of 0.1Hz to 20Khz or so. The area >> of interest right right now is more like 0Hz to 200Hz for simulating a >> pulse counting input to the device under test. >> >> I'm using a $100 function generator for now, but the display resolution >> of 1Hz is somewhat limiting. PC control would also enable me to >> automate some of the testing. >> David... >> > DDS generator will fit the bill. There is an article in recent NutsnVolt= s > magazine that uses PIC to control PLL to do just that, it's trivial to ad= d > serial interface to that. IIRC, total cost was under $70. Yeah, I was thinking of an easy FT232 + DDS chip + buffer design to=20 save time. I haven't used a DDS chip before so was having trouble=20 pinning down something that did low frequencies. They all seem to talk=20 about how many MHz they can do. I'll do a bit more research and see=20 what reasonable cost ones I can find. David... --=20 ___________________________________________ David Duffy Audio Visual Devices P/L Unit 8, 10 Hook St, Capalaba 4157 Australia Ph: +61 7 38235717 Fax: +61 7 38234717 Our Web Site: www.audiovisualdevices.com.au ___________________________________________ --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .