adc/dac interfacing with pic microcontroller - Electronic Circuits Projects Diagrams Free

bebo670 · 15th February 2007, 12:34 PM

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 · 15th February 2007, 04:22 PM

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** · 15th February 2007, 04:30 PM

Quote:

Originally Posted by 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 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.

Quote:

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.

Quote:

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.

Quote:

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 · 16th February 2007, 12:47 AM

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

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15th February 2007, 12:34 PM	(permalink)
bebo670	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

15th February 2007, 04:22 PM	(permalink)
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. __________________ Everybody can but not everybody will.

16th February 2007, 12:47 AM	(permalink)
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