adc/dac interfacing with pic microcontroller

[bebo670]

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

 

[aibelectronics]

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.

 

[Nigel Goodwin]

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 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?

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.

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.

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

 

[bebo670]

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