Microcontroller based Function Generator

How can we know the frequency? we need to feedback the o/p to our controller's i/p to make it read the frequency.

Ajay

thats why i am asking about select the waveform then dial a frequency (pushing up -down button)in this method we already know the frequency of waveform then press start button

hmm.. smart yes that is a good idea.. so how we are going to change frequency?

Once we finish with this discussion.. making this project is not difficult then

well iam not so good on 8051 :blush but by changing loop (for different waves ) time period =T we can cal calculate the frequncy (F) by this simple formula F=1/T

yes... but we will get a distorted wave we if make time delay too much.. i mean.. are you sure 741 will smooth it enough? to get a good looking wave?
I am not sure

ya 741 gives good response under 1Mhz for higher freq. we can select some other op-amp or go for R-2R

R-2R is not for smoothing i replacement for DAC, but i think using a DAC is better...
i hope you understood what i was trying to say..
i was saying that... the o/p frequency depends on how fast we send the changing data to our parallel port of 8051/PC. So when we put a longer delay in sending values to the port it maintain a stable voltage on the o/p unless we send the next value to the port. So my point was is 741 capable of smoothing such o/p signals? you have a ready working program along with the circuit so you can try out... this..
put delay between the values you are sending to the port and see if the frequency is changing or not

i could not gather much but if you r gonna use 51 and R-2R
may be this code snippet would come in handy

we were actually thinking about how to change the frequency.. i think the only method is by varying the delay.. but this can be checked if hardware is ready..
Coding is not a problem yet

Protus can help for hardware checking?
?

hmm... i am not sure... i tried an R-2R network on it.. but CPU load was too much.
I did not try with DAC0808. I will try that too...