adc/dac interfacing with pic microcontroller

hello
this is my first thread here and i really need ur help in this project

i need to make an interfacing circuit which includes a mic and adc/dac and pic 16f877a microcontroller and speaker and the circuit or microcontroller is required to store 5 audio samples and then send them to dac and then to speaker in more simple way i need to make a circuit that acts like a recoder as u speak into a mic then adc sends the samples to microcontroller which is required to store 5 samples then send them to dac and from dac to speaker where i can hear the sound again so can anyone help me with a circuit diagram or pic program coz i am not so good in microcontrollers programming and thanks in advance

Input: you'll need a lowpass filter (with cutoff of about 3400hz, hope I got that correct), a switch (for sample & hold) to be controlled by control signals from your micro. A fast ADC might eliminate the need of the SHC stage.

The rate at which the micro initiates the ON/OFF switching determines your sample rate. You'll need an ADC between micro and input stage. Of course.

By the way, why just 5 samples. Have you considered the quality of your output?

Finally a DAC connected to the serial output of your micro. You'll need an RC filtering scheme at the output to smoothen the staircase shape of your output and approximate it to a sinuisoidal waveform, which is what our voices sound more like. This is just the electronics.

There are a lot of example programs to help you along. You can try out Nigel's page. Lots of stuff there.

aibelectronics said:

Input: you'll need a lowpass filter (with cutoff of about 3400hz, hope I got that correct), a switch (for sample & hold) to be controlled by control signals from your micro. A fast ADC might eliminate the need of the SHC stage.

Click to expand...

The PIC 16F877A he suggested already has an internal 10 bit A2D, which you can configure to use as 8 bit - which would be a good idea for this application.

The rate at which the micro initiates the ON/OFF switching determines your sample rate. You'll need an ADC between micro and input stage. Of course.

By the way, why just 5 samples. Have you considered the quality of your output?

Click to expand...

I think he means 5 sequences of samples?, so 5 seperate sound clips.

Finally a DAC connected to the serial output of your micro. You'll need an RC filtering scheme at the output to smoothen the staircase shape of your output and approximate it to a sinuisoidal waveform, which is what our voices sound more like. This is just the electronics.

Click to expand...

A simple R2R D2A ladder is all you need, followed by a low-pass filter.

There are a lot of example programs to help you along. You can try out Nigel's page. Lots of stuff there.

Click to expand...

There's a tutorial about using the A2D, but the memory storage (as in the other similar thread) is the BIG problem!.

thanks alot guys for ur help i really appreciate it and i will do as u suggested and see what happens and hope everything works fine thanks again guys