As Steve notes, you can use PWM. Depending on what response time you want and how much external hardware you can tolerate you may be able to get N channels of D2A using software PWM. If you have an interrupt 'tick' you can write extremely simple and low code overhead multi channel PWM routines. Worst case cycle time is N interrupts where you want N steps. eg for 8 bit PWM = 256 steps you want 256 IRQs worst case. If the IRQ is 10 uS then the PWM cycle is 2.566 mS. If the IRQ rate is 1 mS the PWM cycle rate (frame length) = 0.256s etc. Simple RC filtering will allow reasonably smooth DC if the filter time constant is >> the frame period. Got 2.56 mS frame rate you may use say about 256 mS filtering. For a slower frame rate the filter settling time gets too long for many purposes (but not all). However, by implementing a few poles of active low pass filtering can get a vastly improved DC response time. By using a jellybeam transistor in emitter follower mode and 2 x R and 2 x C you can get 2 poles and 3 poles with 3R and 3C. Plus maybe a few more R in each case for real world stuff. Add another stage and you can get 4 or 5 poles. The precision of the required components rises IF you want a genuine classic filter implementation , but odds are a 4 pile try hard Bessel filter will work extremely well. Even 2 or 3 poles is much better than a straight RC. Using emitter followers you get some DC offset issues. If you want good precision a cheap op amp per stage makes things much better. If you can use a timer module you can get > or >> 1 Mhz bit rates and filtering gets much easier and simple RC may do in many cases. Adding an opamp unity gain buffer is usually a good idea. Russell On 9 March 2010 09:47, Jason Hsu wrote: > I have used PIC microcontrollers that measure the voltage of a signal > at a particular instant in time with an A/D converter that converts > the value into 0-255 (8-bit) or 0-1023 (10-bit). > > What PIC microcontrollers do the opposite - convert a value (0-255 or > 0-1023) into a 0-5V voltage output? What examples of completed > projects that use the D/A are there? > > -- > Jason Hsu > http://www.jasonhsu.com/swrwatt.html > http://www.jasonhsu.com/swrwatt-c.txt > http://www.jasonhsu.com/swrwatt-asm.txt > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist